Introduction Intra-site Automatic Tunneling Addressing Protocol is an automatic tunneling mechanism which builds a tunnel for carrying IPv6 traffic over IPv4 within an IPv4 network .Like 6to4 tunnels, ISATAP uses the underlying IPv4 network as an NBMA  link layer for IPv6 and determines the destination on a per packet basis i.e. point-to-multipoint.It allows individual IPv4 or IPv6 dual-stack hosts within a site to communicate with other such hosts on the same virtual link, basically creating an IPv6 network using the IPv4 infrastructure.   The main difference between automatic 6to4 tunnels and ISATAP tunnels is that the automatic 6to4 is Inter-site tunnel that allows IPv6 traffic between different sites where as ISATAP as the name specifies is for Intra-site which can be used for transporting IPv6 packets within a site, but not between sites.Another aspect is the address prefix used in sites, 6to4 sites uses addresses from 2002::/16 prefix where as ISATAP tunneling sites can use any IPv6 unicast address.   This document provides sample configuration of IPv6 ISATAP Tunneling in Cisco IOS routers. Requirements   Refer to Implementing IPv6 Addressing and Basic Connectivity for basic understanding on IPv6.   Background   When configuring ISATAP tunneling, there are 2 modes involved.   ISATAP router (it can be a router or server like Windows Server ) which has the IPv6 capabilities enabled and it advertise the network which        nodes can use to configure the IPv6 address when connected to the Ethernet interface. ISATAP Client establishes a static tunnel to the server and requests for IPv6 address.Usually end hosts will be ISATAP clients such as         Windows PC with IPv6 enabled initiates the tunnel with ISATAP router.   The ISATAP router/server uses unicast addresses that include a 64-bit IPv6  prefix and a 64-bit interface identifier. The interface identifier is  created in modified EUI-64 format in which the first 32 bits contain the  value 000:5EFE to indicate that the address is an IPv6 ISATAP address.   In this document, the routers R1, R2 and R3 forms underlying IPv4 network using RIPv2. The router R1 is configured as ISATAP router with IPv6 capabilities enabled. In order to configure ISATAP client, IPv6 unicast routing can be disabled on the client router, so that it  will behave as a true client and install a default IPv6 static route.Loopback addresses are configured on the routers in order to generate networks.   Prerequisites   While configuring ISATAP Tunnel, the tunnel source should be an interface configured with IPv4 address. The tunnel source command used in the configuration of an ISATAP tunnel must point to an  interface with an IPv4 address configured. The IPv6 tunnel interface must be configured with a modified  EUI-64 address because the last 32 bits in the interface identifier are formed using the IPv4 tunnel source address.   Note: All configuration is tested on Cisco 7200 Series Router running on IOS Version  15.0(1)M Advance IP Services Image.   Topology Diagram       Configuration For  complete configuration, see attached files (R1, R2 and R3). - See more  at: https://supportforums.cisco.com/docs/DOC-25487#sthash.XGldzaxO.dpuf   Configuring ISATAP Router Configuring router R1 as ISATAP router involves the following steps:   ! host name R1 ! ipv6 unicast-routing   ! interface Tunnel1 no ip address no ip redirects ipv6 address 2001:DB8:AA10:10::/64 eui-64 !...Note that any /64 IPv6 address will work no ipv6 nd ra suppress !...On a tunnel interface, IPv6 router advertisements (IPv6 ra) is suppressed by default. This command re-enables sending IPv6 Ra's and also allows client auto-configuration. tunnel source Loopback0 !...The tunnel source should be an interface configured with IPv4 address. tunnel mode ipv6ip isatap !...Enables IPv6 overlay tunnel using a ISATAP address. ! end Configuring ISATAP Client Configuring router R3 as ISATAP client involves the following steps:   ! hostname R3 ! !.. Note that IPv6 Unicast routing is not configured in the client router ! interface Tunnel1 no ip address ipv6 address autoconfig !...ISATAP client tunnel 1 acquires IPv6 address automatically from ISATAP router and appends the client's IPv4 address at the end. ipv6 enable tunnel source GigabitEthernet1/0 tunnel mode ipv6ip tunnel destination 1.1.1.1 ! end   Note: For complete configuration,see attached files (R1, R2 and R3) For  complete configuration, see attached files (R1, R2 and R3). - See more  at: https://supportforums.cisco.com/docs/DOC-25487#sthash.XGldzaxO.dpuf For  complete configuration, see attached files (R1, R2 and R3). - See more  at: https://supportforums.cisco.com/docs/DOC-25487#sthash.XGldzaxO.dpuf   Verify Commands Show IPv6 Interface   To display the detailed information of the tunnel interface, use this command .   In router R1   R1#show ipv6 interface tunnel 1 Tunnel1 is up, line protocol is up   IPv6 is enabled, link-local address is FE80::5EFE:101:101   No Virtual link-local address(es):   Global unicast address(es):     2001:DB8:AA10:10:0:5EFE:101:101, subnet is 2001:DB8:AA10:10::/64 [EUI]   Joined group address(es):     FF02::1     FF02::2     FF02::1:FF01:101   MTU is 1480 bytes   ICMP error messages limited to one every 100 milliseconds   ICMP redirects are enabled   ICMP unreachables are sent   ND DAD is not supported   ND reachable time is 30000 milliseconds (using 30000)   ND advertised reachable time is 0 (unspecified)   ND advertised retransmit interval is 0 (unspecified)   ND router advertisements are sent every 200 seconds   ND router advertisements live for 1800 seconds   ND advertised default router preference is Medium   Hosts use stateless autoconfig for addresses.   In the above output you can see that the IPv6 address is formed using eui-64 mechanism but in a modified format.The eui-64 prefix    2001:DB8:AA10:10 is followed by 0000:5EFE indicating that the address is an ISATAP address and then the next 32 bits are taken from IPv4 address of the source interface i.e. in our case its loopback interface 0 which has IPv4 address 1.1.1.1------->Converted to HEX forms---->101:101.   In router R3   R3#show ipv6 interface tunnel 1 Tunnel1 is up, line protocol is up   IPv6 is enabled, link-local address is FE80::AC10:6402   No Virtual link-local address(es):   Stateless address autoconfig enabled   Global unicast address(es):    2001:DB8:AA10:10::AC10:6402, subnet is 2001:DB8:AA10:10::/64 [EUI/CAL/PRE]       valid lifetime 2591892 preferred lifetime 604692   Joined group address(es):     FF02::1     FF02::1:FF10:6402   MTU is 1480 bytes   ICMP error messages limited to one every 100 milliseconds   ICMP redirects are enabled   ICMP unreachables are sent   ND DAD is enabled, number of DAD attempts: 1   ND reachable time is 30000 milliseconds (using 30000)   Default router is FE80::5EFE:101:101 on Tunnel1   The above output shows that the ISATAP client has received its IPv6 prefix from the ISATAP router which is 2001:DB8:AA10:10 and appended its IPv4 address of the source interface G1/0 address 172.16.100.2---->Converted to HEX---->AC10:6402.   Also note that the default router is given as ISATAP router R1 by appending the ISATAP address identifier 0:5EFE with source interface Lo 0 address 1.1.1.1--->converted to HEX--->101:101 forming the default router address as FE80::5EFE:101:101   Show ipv6 route   To display routing table information   R3#show ipv6 route IPv6 Routing Table - default - 4 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route        B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP        I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary        D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery        O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2        ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S   ::/0 [2/0]      via FE80::5EFE:101:101, Tunnel1 C   2001:DB8:AA10:10::/64 [0/0]      via Tunnel1, directly connected L   2001:DB8:AA10:10::AC10:6402/128 [0/0]      via Tunnel1, receive L   FF00::/8 [0/0]      via Null0, receive   Note that we have disabled the IPv6 unicast routing in client router, the router has installed a static route pointing to Tunnel 1 i.e. towards ISATAP router.   Ping   Now the ISATAP router should be able to ping the client i.e. router R3   R1#ping 2001:DB8:AA10:10::AC10:6402   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:AA10:10::AC10:6402, timeout is 2 seconds: !!!!!     References Implementing Tunneling for IPv6 IPv6:Providing IPv6 Services over an IPv4 Backbone Using Tunnels IPv6 Tunnel through an IPv4 Network IP Version 6 (IPv6) - Cisco Systems Cisco IOS IPv6 Command Reference IPv6 - Frequently Asked Questions Routing Information Protocol ... View more

        Introduction This document provides sample configuration of IPv6 6to4 tunneling in Cisco IOS routers. 6to4 Tunneling is one of the IPv6 translation mechanism which encapsulates the IPv6 packets into IPv4 which allows remote IPv6 networks to communicate across the IPv4 infrastructure(core network or Internet). The main difference between the manual tunnels and automatic 6to4 tunnels is that the tunnel is not point-to-point but it is point-to-multipoint.   In automatic 6to4 tunnels, the IPv4 infrastructure is treated as a  virtual nonbroadcast multiaccess (NBMA) link routers are not  configured as point-to-point. The IPv4 address embedded  in the IPv6 address is used to find the other end of the automatic  tunnel. Requirements   Refer to Implementing IPv6 Addressing and Basic Connectivity for basic understanding on IPv6.   Background   In this example, router R1 and R2 are connected via Gigabit Ethernet G1/0. The routers R1 and R2 runs OSPFv3 in their internal network with routers R3 and R4 respectively. Note that internal routing protocols such as EIGRPv6 OSPFv3 cannot be used across the 6to4 tunnels since they use Link-Local address to form adjacencies. You can either use BGP which forms adjacencies using Global Unicast Address or Static routes as we use in this example.   Note: All configuration is tested on Cisco 7200 Series Router running on IOS Version  15.0(1)M Advance IP Services Image.   Topology Diagram       Configuration                        Router R1                        Router R2            Router R3 & R4 ! version 15.2 ! hostname R1 ! ipv6 unicast-routing ipv6 cef ! interface Tunnel0 no ip address no ip redirects ipv6 address 2002:C0A8:1E01::/48 tunnel source 192.168.30.1 tunnel mode ipv6ip 6to4 ! interface GigabitEthernet1/0 ip address 192.168.30.1 255.255.255.0 negotiation auto ! interface FastEthernet2/0 no ip address speed auto duplex auto ipv6 address 1000::2/64 ipv6 ospf 1 area 0 ! ipv6 route 2002:C0A8:1E02::/48 Tunnel0 ipv6 route 1010::/64 2002:C0A8:1E02:: ! ipv6 router ospf 1 router-id 1.1.1.1 redistribute static ! ! end                 ! version 15.2 ! hostname R2 ! ipv6 unicast-routing ipv6 cef ! interface Tunnel0 no ip address no ip redirects ipv6 address 2002:C0A8:1E02::/48 tunnel source 192.168.30.2 tunnel mode ipv6ip 6to4 ! interface GigabitEthernet1/0 ip address 192.168.30.2 255.255.255.0 negotiation auto ! interface FastEthernet2/0 no ip address speed auto duplex auto ipv6 address 1010::1/64 ipv6 ospf 1 area 0 ! ipv6 route 2002:C0A8:1E01::/48 Tunnel0 ipv6 route 1000::/64 2002:C0A8:1E01:: ipv6 router ospf 1 router-id 2.2.2.2 redistribute static ! ! end                 ! version 15.2   ! hostname R3 ! ipv6 unicast-routing   ipv6 cef !interface FastEthernet1/0 no ip address speed auto duplex auto ipv6 address 1000::1/64 ipv6 ospf 1 area 0 ! ipv6 router ospf 1 router-id 3.3.3.3 ! ! end   ! version 15.2 ! hostname R4 ! ipv6 unicast-routing ipv6 cef ! ! interface FastEthernet1/0   no ip address   speed auto   duplex auto   ipv6 address 1010::2/64   ipv6 ospf 1 area 0 ! ! ipv6 router ospf 1   router-id 4.4.4.4 ! ! end   Note: Necessary Static routes are configured to achieve connectivity across 6to4 tunnel. First a static route is created for 2002:C0A8:1E02::/48 to be reachable via Tunnel Interface and then another static route for the internal /64 route which is to be routed via 6to4 tunnel interface. Verify Commands Ping To verify the connectivity across the 6to4 tunnels, you can ping the internal networks of router R1 and R2. i.e. The routers R4 and R3 should be able to ping each other.   In router R3   Try ping router R4 (1010::2) from router R3 . R3#ping 1010::2   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 1010::2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 88/156/240 ms   Similarly from Router R4, ping router R3 (1000::1)   R4#ping 1000::1   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 1000::1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 64/212/548 ms   Show ipv6 route   To display routing table information   R1#show ipv6 route IPv6 Routing Table - default - 7 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route        B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP        I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary        D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery        O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2        ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 O   1000::1/128 [110/1]      via FE80::C807:8EFF:FEB4:1C, FastEthernet2/0 LC  1000::2/128 [0/0]      via FastEthernet2/0, receive S   1010::/64 [1/0]      via 2002:C0A8:1E02:: C   2002:C0A8:1E01::/48 [0/0]      via Tunnel0, directly connected L   2002:C0A8:1E01::/128 [0/0]      via Tunnel0, receive S   2002:C0A8:1E02::/48 [1/0]      via Tunnel0, directly connected L   FF00::/8 [0/0]      via Null0, receive R2#show ipv6 route IPv6 Routing Table - default - 7 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route        B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP        I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary        D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery        O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2        ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S   1000::/64 [1/0]      via 2002:C0A8:1E01:: O   1010::1/128 [110/1]      via FE80::C808:8EFF:FEB4:1C, FastEthernet2/0 LC  1010::2/128 [0/0]      via FastEthernet2/0, receive S   2002:C0A8:1E01::/48 [1/0]      via Tunnel0, directly connected C   2002:C0A8:1E02::/48 [0/0]      via Tunnel0, directly connected L   2002:C0A8:1E02::/128 [0/0]      via Tunnel0, receive L   FF00::/8 [0/0]      via Null0, receive   You can see that the static routes are shown in the routing table and is received via Tunnel 0.   Show ipv6 interface tunnel 0   To display the detailed information of the interface, use this command   R1#show ipv6 interface tunnel 0 Tunnel0 is up, line protocol is up   IPv6 is enabled, link-local address is FE80::C0A8:1E01   No Virtual link-local address(es):   Global unicast address(es):     2002:C0A8:1E01::, subnet is 2002:C0A8:1E01::/48   Joined group address(es):     FF02::1     FF02::2     FF02::1:FF00:0     FF02::1:FFA8:1E01   MTU is 1480 bytes   ICMP error messages limited to one every 100 milliseconds   ICMP redirects are enabled   ICMP unreachables are sent   ND DAD is not supported   ND reachable time is 30000 milliseconds (using 30000)   Hosts use stateless autoconfig for addresses.   Traceroute   To trace the path of the packet for reaching the destination use this command.   R3#traceroute 1010::2   Type escape sequence to abort. Tracing the route to 1010::2     1 1000::2 144 msec 156 msec 28 msec   2 2002:C0A8:1E02:: 184 msec 112 msec 120 msec   You can see that the router R3 reaches the network 1010:: via Tunnel interface   References Implementing Tunneling for IPv6 IPv6:Providing IPv6 Services over an IPv4 Backbone Using Tunnels IPv6 Tunnel through an IPv4 Network IP Version 6 (IPv6) - Cisco Systems Cisco IOS IPv6 Command Reference IPv6 - Frequently Asked Questions Routing Information Protocol ... View more

    Introduction This document discuss with an example how to configure dynamic overload mapping in NAT64.  The configuration is same as in the dynamic mapping except that in PAT, multiple IPv6 addresses are mapped to single IPv4 addresses. In other words NAT64 Dynamic overload mapping provides N:1 mapping of IPv6 addresses to IPv4 address.   Requirements   Understanding of IPv6 Addressing Scheme Understanding NAT64   Background   This network set up has routers R1,R2 and R3 connected via Fast Ethernet interface. Loopback addresses are configured in routers R1 and R3 in order to generate networks.The router R1 is IPv4 router communicates with ASR using RIP.Router R3 is IPv6 router uses RIPv6 to communicate with ASR.The network address translations happen in ASR router by mapping specific translations to specific ports for a given IPv4 address.   Note: All configurations are tested in a lab environment on Cisco 2800 Routers operating on Cisco IOS 15.0 and ASR operating on Cisco IOS-XE 15.1(3)S4version.   Topology Diagram     Summary Steps   NAT64 Interface Configuration ipv6 address <Specify an IPv6 address> nat64 enable exit   NAT64 Dynamic Overload Mapping Configuration enable configure terminal ipv6 access-list < access-list-name> permit ipv6 <ipv6-address > any exit nat64 prefix stateful <prefix> Note: The above command enables the router to translate the source IP address to IPv6 by using the  Stateful NAT64 prefix    7. nat64 v4 pool <pool-name> <start-ip-address end-ip-address>    8 . nat64 v6v4 list <access-list-name> pool < pool-name> overload    9. exit   Configuration   Please see attached files for configuration of routers R1, R2 and R3.     IPv4 Router ASR Router IPv6 Router ! version 15.0 ! hostname IPv4_Router ! ip cef ! ! ip multicast-routing ! ! interface Loopback10 ip address 15.1.1.10 255.255.255.0 ! ! interface Loopback20 ip address 25.1.1.10 255.255.255.0 ! ! interface Loopback30 ip address 35.1.1.10 255.255.255.0 ! ! interface FastEthernet0/1 ip address 20.20.20.2 255.255.255.0 duplex auto speed auto ! router rip version 2 network 15.0.0.0 network 20.0.0.0 network 25.0.0.0 network 35.0.0.0 ! ip route 27.1.1.0 255.255.255.0 20.20.20.1 ! ! end ! version 15.1 ! hostname ASR_Router ! ! ipv6 unicast-routing ! ! interface GigabitEthernet0/0/0 ipv6 address 4001::1/96 ipv6 rip RIPv6 enable nat64 enable cdp enable ! ! interface GigabitEthernet0/0/1 ip address 20.20.20.1 255.255.255.0 load-interval 30 negotiation auto nat64 enable cdp enable ! ! router rip network 20.0.0.0 ! ipv6 router rip RIPv6 ! ! ! ipv6 access-list ACLv6 permit ipv6 4001::/96 any ! ! nat64 prefix stateful 2001::/96 nat64 v4 pool pool1 27.1.1.10 27.1.1.10 nat64 v6v4 list ACLv6 pool pool1 overload ! end ! version 15.0 ! hostname IPv6_Router ! ! ipv6 unicast-routing ipv6 cef ! ! interface Loopback10 no ip address ipv6 address 4001::10/128 ipv6 rip RIPv6 enable ! ! interface Loopback20 no ip address ipv6 address 4001::20/128 ipv6 rip RIPv6 enable ! ! interface Loopback30 no ip address ipv6 address 4001::30/128 ipv6 rip RIPv6 enable ! ! interface GigabitEthernet0/1 ip address 10.10.10.2 255.255.255.0 duplex auto speed auto ipv6 address 4001::2/96 ipv6 rip RIPv6 enable ! ! ipv6 route 2001::/96 4001::1 ipv6 router rip RIPv6 ! ! ! end     Verify Commands   If you look at the configuration above, it is much similar to the Dynamic Mapping Configuration where the only difference is adding the keyword Overload to the NAT64 configuration statement.   In our case, the IPv6 router can reach all the IPv4 addresses (Loopback address configured) by using single IPv4 address which is 27.1.1.10 configured in NAT64 address pool.   Similarly You can ping from multiple IPv6 addresses (using the source as Loopback address) to the IPv4 side. All the IPv6 addresses will be mapped to single IPv4. In both the cases, specific address is mapped to specific ports. This can be verified with help of ping and debug commands   Verifying Connectivity Using Ping Command   Enable debug commands on both IPv4 and IPv6 routers and verify connectivity using ping command   In router R3   Ping router R1(IPv4 Router) interface fa0/1 and loopback addresses from router R3 (IPv6 router) by converting to their respective HEX format.   IPv6_Router#ping 2001::1414:1402 (HEX format Fa0/1 IPv4 address 20.20.20.2)   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1414:1402, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms IPv6_Router#ping 2001::f01:10a (HEX format Lo 10 IPv4 address 15.1.1.10)   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::F01:10A, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms IPv6_Router#ping 2001::1901:10a(HEX format Lo 20 IPv4 address 25.1.1.10)   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1901:10A, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms IPv6_Router#ping 2001::2301:10a(HEX format Lo 30 IPv4 address 35.1.1.10)   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::2301:10A, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms     The debug ip icmp  command output on IPv4 router is shown below:   IPv4_Router#debug ip icmp ICMP packet debugging is on IPv4_Router# *Dec 20 10:17:16.818: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 20 10:17:28.218: ICMP: echo reply sent, src 15.1.1.10, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 20 10:17:40.958: ICMP: echo reply sent, src 25.1.1.10, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 20 10:17:50.086: ICMP: echo reply sent, src 35.1.1.10, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 <Output omitted>   From the above output you can see that all the ping replies are directed to single IPv4 address 27.1.1.10 configured in NAT64 address pool   The show nat64 translation command displays the address translations happened in detail.   ASR_Router#show nat64 translation   Proto  Original IPv4         Translated IPv4        Translated IPv6       Original IPv6 ----------------------------------------------------------------------------   icmp   35.1.1.10:4           [2001::2301:10a]:6575        27.1.1.10:4           [4001::2]:6575 icmp   20.20.20.2:1          [2001::1414:1402]:9615        27.1.1.10:1           [4001::2]:9615 icmp   25.1.1.10:3           [2001::1901:10a]:4815        27.1.1.10:3           [4001::2]:4815 icmp   15.1.1.10:2           [2001::f01:10a]:6797        27.1.1.10:2           [4001::2]:6797   Total number of translations: 4   The above output shows that the different address are mapped to different port and replied are sent to single IPv4 address which is 27.1.1.10   Similarly you can ping the IPv4 side from the configured IPv6 loopback addresses by using the command ping <IPv6 address> source <Interface address> and verify the translation on the ASR router with the command show nat64 translation   IPv6_Router#ping 2001::1414:1402 source lo 10   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1414:1402, timeout is 2 seconds: Packet sent with a source address of 4001::10 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms IPv6_Router#ping 2001::1414:1402 source lo 20   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1414:1402, timeout is 2 seconds: Packet sent with a source address of 4001::20 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms IPv6_Router#ping 2001::1414:1402 source lo 30   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1414:1402, timeout is 2 seconds: Packet sent with a source address of 4001::30 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/1/4 ms IPv6_Router#ping 2001::1414:1402 source g0/1   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1414:1402, timeout is 2 seconds: Packet sent with a source address of 4001::2 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/1/4 ms     ASR_Router#show nat64 translation   Proto  Original IPv4         Translated IPv4        Translated IPv6       Original IPv6 ----------------------------------------------------------------------------   icmp   20.20.20.2:2          [2001::1414:1402]:6454        27.1.1.10:2           [4001::20]:6454 icmp   20.20.20.2:4          [2001::1414:1402]:2719        27.1.1.10:4           [4001::2]:2719 icmp   20.20.20.2:1          [2001::1414:1402]:2001        27.1.1.10:1           [4001::10]:2001 icmp   20.20.20.2:3          [2001::1414:1402]:3353        27.1.1.10:3           [4001::30]:3353   Total number of translations: 4   The above output shows that the different IPv6 loopback  addresses are translated to single IPv4 address 27.1.1.10 by mapping them in to different ports.   Some useful show commands that can be used to see NAT64 translations in ASR router   Show nat64 mappings static   This command display the information about the Network Address Translation 64 (NAT64) dynamic mappings , use this command.   ASR_Router#show nat64 mappings dynamic Dynamic mappings configured: 1 Direction ACL    Pool                             Flags v6v4      ACLv6    pool1                            0x00000001 (overload) Show nat64 adjacency ipv6   This command displays the information about the Network Address Translation 64 (NAT64) managed adjacencies.   ASR_Router#show nat64 adjacency ipv6 Adjacency Counts    Stateless Prefix Adjacencies: 0    Stateless Prefix Adjacency Ref Count: 0    v4v6 Stateless Prefix Adjacencies: 0    v4v6 Stateless Prefix Adjacency Ref Count: 0    v6v4 Stateless Prefix Adjacencies: 0    v6v4 Stateless Prefix Adjacency Ref Count: 0    Stateful Prefix Adjacencies: 1    Stateful Prefix Adjacency Ref Count: 1    IPv6 Well-Known Prefix Adjacencies: 1    IPv6 Well-Known Prefix Adjacency Ref Count: 1    IPv6 Static Mapping Adjacencies: 0    IPv6 Static Mapping Adjacency Ref Count: 0    IPv4 Static Mapping Adjacencies: 0    IPv4 Static Mapping Adjacency Ref Count: 0    IPv4 Pool Adjacencies: 1    IPv4 Pool Adjacency Ref Count: 1    IPv4 Route Adjacencies: 0 Adjacencies    Stateful Prefix: ::100.0.0.1    IPv6 Well-Known Prefix: ::100.0.0.2    IPv6 Stateful Mask: ::100.0.0.0    IPv4 Pool: 100.0.0.2    IPv4 Stateful Mask: 100.0.0.0   Show nat64 prefix stateful   Using this command, you can check the information about Network Address Translation 64 (NAT64) stateful prefixes. Global prefixes, nat64 configured intrerfaces and prefix static-routes will be displayed.   ASR_Router#show nat64 prefix stateful global (Displays the global prefixes)   Global Stateful Prefix: is valid, 2001::/96   IFs Using Global Prefix      Gi0/0/0    Gi0/0/1 ASR_Router#show nat64 prefix stateful interfaces (Displays the nat64 enabled interfaces) Stateful Prefixes Interface    NAT64 Enabled Global Prefix   GigabitEthernet0/0/0    TRUE          TRUE   2001::/96 GigabitEthernet0/0/1    TRUE          TRUE   2001::/96 ASR_Router#show nat64 prefix stateful static-routes (Displays the static-routes) Stateful Prefixes NAT64 Prefix    Static Route Ref-Count   2001::/96    1   Show nat64 statistics   To display Network Address Translation 64 (NAT64) packet count statistics use this command   ASR_Router#show nat64 statistics NAT64 Statistics Total active translations: 1 (0 static, 1 dynamic; 1 extended) Sessions found: 251 Sessions created: 29 Expired translations: 26 Global Stats:    Packets translated (IPv4 -> IPv6)       Stateless: 0       Stateful: 135    Packets translated (IPv6 -> IPv4)       Stateless: 0       Stateful: 140 Interface Statistics    GigabitEthernet0/0/0 (IPv4 configured, IPv6 configured):       Packets translated (IPv4 -> IPv6)          Stateless: 0          Stateful: 0       Packets translated (IPv6 -> IPv4)          Stateless: 0          Stateful: 140       Packets dropped: 0    GigabitEthernet0/0/1 (IPv4 configured, IPv6 not configured):       Packets translated (IPv4 -> IPv6)          Stateless: 0          Stateful: 135       Packets translated (IPv6 -> IPv4)          Stateless: 0          Stateful: 0       Packets dropped: 5 Dynamic Mapping Statistics    v6v4       access-list ACLv6 pool pool1 refcount 1          pool pool1:             start 27.1.1.10 end 27.1.1.10             total addresses 1, allocated 1 (100%)             address exhaustion packet count 0 Limit Statistics References   NAT64 Technology: Connecting IPv6 and IPv4 Networks NAT64—Stateless versus Stateful Stateful Network Address Translation 64 Stateless IPv6 NAT64 Configuration IP Version 6 (IPv6) - Cisco Systems Cisco IOS IPv6 Command Reference IPv6 - Frequently Asked Questions Routing Information Protocol ... 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    Introduction This document discuss with an example how to configure NAT64 using dynamic mapping. In this dynamic configuration an IPv4 address pool is created and is associated with an IPv6 ACL. The translation is done in such a way that  there is one to one mapping of IPv6 address to the configured IPv4 address pool. Note that in case of dynamic mapping the initial communication needs to flow from IPv6 network towards the IPv4 network.   Requirements   Understanding of IPv6 Addressing Scheme Understanding NAT64   Background   In this configuration example, routers R1,R2 and R3 are connected via fast Ethernet interface.The router R1 is IPv4only router and router R3 is IPv6 only router. Both R1 and R2 are connected to ASR and has static routes configured pointing towards the respective ASR interface. The network address translations happen in ASR router using dynamic mappings of IPv6 address to the IPv4 address pool.   Note: All configurations are tested in a lab environment on Cisco 2800 Routers operating on Cisco IOS 15.0 and ASR operating on Cisco IOS-XE 15.1(3)S4version.   Topology Diagram     Summary Steps   NAT64 Interface Configuration ipv6 address <Specify an IPv6 address> nat64 enable exit   NAT64 Dynamic Configuration enable configure terminal ipv6 access-list < access-list-name> permit ipv6 <ipv6-address > any exit nat64 prefix stateful <prefix> Note: The above command enables the router to translate the source IP address to IPv6 by using the  Stateful NAT64 prefix    7. nat64 v4 pool <pool-name> <start-ip-address end-ip-address>    8 . nat64 v6v4 list <access-list-name> pool < pool-name>       9. exit   Configuration     Router R1 IPv4 Only Router Router R2 ASR Router Router R3 IPv6 Only Router ! version 15.0 ! hostname IPv4_Only _Router !   ip cef ! interface FastEthernet0/1 ip address 20.20.20.2 255.255.255.0 duplex auto speed auto ! ip route 27.1.1.0 255.255.255.0 20.20.20.1 ! end ! version 15.1 ! hostname ASR_Router ! ! ipv6 unicast-routing ! ! interface GigabitEthernet0/0/0   ipv6 address 4001::1/96 nat64 enable cdp enable ! interface GigabitEthernet0/0/1 ip address 20.20.20.1 255.255.255.0 load-interval 30 negotiation auto nat64 enable cdp enable ! ! ipv6 access-list ACLv6 permit ipv6 4001::/64 any ! ! nat64 prefix stateful 2001::/96 nat64 v4 pool pool1 27.1.1.10 27.1.1.11 nat64 v6v4 list ACLv6 pool pool1 ! end ! version 15.0 ! hostname IPv6_Only_Router ! ! ipv6 unicast-routing ipv6 cef ! ! interface GigabitEthernet0/1 ip address 10.10.10.2 255.255.255.0 duplex auto speed auto ipv6 address 4001::2/96 ! ! ipv6 route 2001::/96 4001::1 ! ! end     Verify Commands   Verifying Connectivity Using Ping Command   You can verify the connectivity across IPv4 and IPv6 network by using the ping command and to verify the translations happen at IPv4 side and IPv6 side of the network use the command debug ip icmp on router  R1(IPv4_Only_Router) and debug ipv6 icmp on router R3(IPv6_Only_Router).   In router R3   Try ping router R1(IPv4 only network)is represented by the IPv6 address 2001::1414:1402.   Note: The IPv6 address 2001::1414:1402 is nothing but the Router R1's (IPv4 Router) interface Fa0/1 address 20.20.20.2 in HEX format.   IPv6_Only_Router#debug ipv6 icmp   ICMP Packet debugging is on IPv6_Only_Router#ping 2001::1414:1402   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001::1414:1402, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms IPv6_Only_Router# *Dec 14 13:03:17.026: ICMPv6: Sent echo request, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:03:17.026: ICMPv6: Received echo reply, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:03:17.026: ICMPv6: Sent echo request, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:03:17.030: ICMPv6: Received echo reply, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:03:17.030: ICMPv6: Sent echo request, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:03:17.030: ICMPv6: Received echo reply, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:03:17.030: ICMPv6: Sent echo request, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:03:17.034: ICMPv6: Received echo reply, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:03:17.034: ICMPv6: Sent echo request, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:03:17.034: ICMPv6: Received echo reply, src=2001::1414:1402, Dst=4001::2   Note that ping is initiated from the IPv6 side of the network and we receive successful replies from the router R1.Enable the debug ip icmp in the router R1 as well you can, see that the replies are being sent to 27.1.1.10 which is the IP address configured in the dynamic nat64 pool. The debug output from router R1(IPv4_Only_Router) is shown below:   *Dec 14 12:42:41.078: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:41.078: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:41.078: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:41.082: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:41.082: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:50.386: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:50.390: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:50.390: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:50.394: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0 *Dec 14 12:42:50.394: ICMP: echo reply sent, src 20.20.20.2, dst 27.1.1.10, topology BASE, dscp 0 topoid 0   The connectivity from IPv4 network to IPv6 network is verified by pinging the IPv4 address 27.1.1.10 which represents the IPv6 side.   Note: The IPv4 address 27.1.1.10 is the address configured in the NAT64 address pool.   IPv4_Only _Router#ping 27.1.1.10   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 27.1.1.10, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms   *Dec 14 13:09:26.254: ICMPv6: Received echo request, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:09:26.254: ICMPv6: Sent echo reply, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:09:26.254: ICMPv6: Received echo request, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:09:26.254: ICMPv6: Sent echo reply, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:09:26.258: ICMPv6: Received echo request, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:09:26.258: ICMPv6: Sent echo reply, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:09:26.258: ICMPv6: Received echo request, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:09:26.258: ICMPv6: Sent echo reply, src=4001::2, Dst=2001::1414:1402 *Dec 14 13:09:26.262: ICMPv6: Received echo request, src=2001::1414:1402, Dst=4001::2 *Dec 14 13:09:26.262: ICMPv6: Sent echo reply, src=4001::2, Dst=2001::1414:1402   The following show commands can be used to see NAT64 translations that happen in ASR router   Show nat64 translation   To display the NAT64 translations in ASR use this command   ASR_Router#show nat64 translation Proto  Original IPv4         Translated IPv4         Translated IPv6       Original IPv6 ---------------------------------------------------------------------------- ---    ---                   ---         27.1.1.10             4001::2 icmp   20.20.20.2:1          [2001::1414:1402]:1         27.1.1.10:1           [4001::2]:1 icmp   20.20.20.2:3502       [2001::1414:1402]:3502         27.1.1.10:3502        [4001::2]:3502 Total number of translations: 3   Show nat64 mappings static   To display the information about the Network Address Translation 64 (NAT64) dynamic mappings , use this command.   ASR_Router#show nat64 mappings dynamic Dynamic mappings configured: 1 Direction ACL    Pool                             Flags v6v4      ACLv6 pool1                            0x00000000 (none) Show nat64 adjacency ipv6   This command displays the information about the Network Address Translation 64 (NAT64) managed adjacencies.   ASR_Router#show nat64 adjacency ipv6   Adjacency Counts      Stateless Prefix Adjacencies: 0    Stateless Prefix Adjacency Ref Count: 0    v4v6 Stateless Prefix Adjacencies: 0    v4v6 Stateless Prefix Adjacency Ref Count: 0    v6v4 Stateless Prefix Adjacencies: 0    v6v4 Stateless Prefix Adjacency Ref Count: 0    Stateful Prefix Adjacencies: 1    Stateful Prefix Adjacency Ref Count: 1    IPv6 Well-Known Prefix Adjacencies: 1    IPv6 Well-Known Prefix Adjacency Ref Count: 1    IPv6 Static Mapping Adjacencies: 0    IPv6 Static Mapping Adjacency Ref Count: 0    IPv4 Route Adjacencies: 0 Adjacencies      Stateful Prefix: ::100.0.0.1    IPv6 Well-Known Prefix: ::100.0.0.2    IPv6 Stateful Mask: ::100.0.0.0   Show nat64 prefix stateful   Using this command, you can check the information about Network Address Translation 64 (NAT64) stateful prefixes. Global prefixes, nat64 configured intrerfaces and prefix static-routes will be displayed.   ASR_Router#show nat64 prefix stateful global (Displays the global prefixes)   Global Stateful Prefix: is valid, 3001::/96 IFs Using Global Prefix    Fa0/2/6    Fa0/2/7   ASR_Router#show nat64 prefix stateful static-routes (Displays the static-routes) Stateful Prefixes NAT64 Prefix    Static Route Ref-Count 3001::/96    1   ASR_Router#show nat64 prefix stateful interfaces (Displays the nat64 enabled interfaces) Stateful Prefixes   Interface    NAT64 Enabled Global Prefix   FastEthernet0/2/6    TRUE          TRUE   3001::/96 FastEthernet0/2/7    TRUE          TRUE   3001::/96   Show nat64 statistics   To display Network Address Translation 64 (NAT64) packet count statistics use this command ASR_Router#show nat64 statistics NAT64 Statistics Total active translations: 2 (0 static, 2 dynamic; 1 extended) Sessions found: 242 Sessions created: 28 Expired translations: 25 Global Stats:    Packets translated (IPv4 -> IPv6)       Stateless: 0       Stateful: 130    Packets translated (IPv6 -> IPv4)       Stateless: 0       Stateful: 135 Interface Statistics    GigabitEthernet0/0/0 (IPv4 configured, IPv6 configured):       Packets translated (IPv4 -> IPv6)          Stateless: 0          Stateful: 0       Packets translated (IPv6 -> IPv4)          Stateless: 0          Stateful: 135       Packets dropped: 0    GigabitEthernet0/0/1 (IPv4 configured, IPv6 not configured):       Packets translated (IPv4 -> IPv6)          Stateless: 0          Stateful: 130       Packets translated (IPv6 -> IPv4)          Stateless: 0          Stateful: 0       Packets dropped: 5 Dynamic Mapping Statistics    v6v4       access-list ACLv6 pool pool1 refcount 2          pool pool1:             start 27.1.1.10 end 27.1.1.11             total addresses 2, allocated 1 (50%)             address exhaustion packet count 0 Limit Statistics References   NAT64 Technology: Connecting IPv6 and IPv4 Networks NAT64—Stateless versus Stateful Stateful Network Address Translation 64 Stateless IPv6 NAT64 Configuration IP Version 6 (IPv6) - Cisco Systems Cisco IOS IPv6 Command Reference IPv6 - Frequently Asked Questions Routing Information Protocol ... 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    Introduction Network Time Protocol NTP is a protocol to synchronize time on network  of machines.This is done getting time from an authoritative time source  such as Atomic Clock or Radio clock attached to the time server.This  time is then distributed across the network and this is being done so  efficiently where in a network having 2 devices will have the time  updated to the accuracy of within a millisecond of one another.NTP runs  on UPD which in turn run on IPv4.   NTPv4 is an extension to the current NTPv3 where it  supports both IPv4 and IPv6 and is backward compatible with NTPv3. Some  of main features of NTPv4 are discussed here:   IPv6 Support   NTPv4  extends its support for IPv6 there by enabling NTP time synchronization  possible over IPv6.Unlike NTPv3 which uses IPv4 broadcast message to  send and receive clock updates, the NTPv4 for IPv6 uses IPv6 Multicast  multicast messages for synchronization of clocks.   Enhanced Security   NTPv4  uses Symmetric Key Authentication which provides a strong cryptographic  authentication mechanism which efficiently prevents the local router  from being wrongly updated with incorrect time by any intruder. In this  NTP symmetric Key Authentication, the keys are distributed manually on  the NTP devices across the network.Note that NTPv4 group functionality  supports both IPv6 named access list and IPv4 numbered access list.   DNS Support For IPv6   In  NTPv3, the host names are resolved in to IPv4 addresses and the  resolved IPv4 addresses are  kept in memory stored in NVRAM but the host  names are lost.In case of NTPv4, the host names are also stored in  memory so that it can be readable and the configurations saved with host  names are still readable by NTPv3. How to Configure NTPv4 in IPv6 Summary Steps: In Configuration mode:   To enable the client software clock to be synchronized by the NTP time server, use the command ntp server <IPv6 address> version 4   To configure the symmetric active mode where the clients will be able to synchronize the time from its peer use the command ntp peer <IPv6 address of the peer> version 4   In order to enable NTPv4 authentication, configure the below commands   ntp authenticate enables NTPv4 authentication   ntp authentication-key number md5 value  defines  authentication key for NTPv4.   ntp trusted-key key-number authenticates the identity of a system to which NTPv4 will synchronize   Useful Show Commands   The following show commands can be used to display the cache content and cache statistics   show clock <detail> This command displays the date and time from the system software clock and the keyword detail is used to check the clock source i.e. through NTP or hardware clock etc..Example: Router> show clock detail *12:40:55.911 PST Thu Nov 29 2012 Time source is NTP show ntp associations <detail>   R1#show ntp association detail 2001:DB8:AA10::2 configured, insane, invalid, unsynced, stratum 16 ref ID .INIT., time D461D902.5B2530A4 (12:52:18.356 PST Thu Nov 29 2012) our mode client, peer mode unspec, our poll intvl 64, peer poll intvl 1024 root delay 0.00 msec, root disp 0.00, reach 0, sync dist 15940.75 delay 0.00 msec, offset 0.0000 msec, dispersion 15937.50 precision 2**24, version 4 org time AFE252E2.3AC0E887 (00:12:34.229 PDT Tue Oct 4 2011) rec time D461D902.5B2530A4 (12:52:18.356 PST Thu Nov 29 2012) xmt time D461D4E5.852FF670 (12:34:45.520 UTC Thu Nov 29 2012) filtdelay =     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00 filtoffset =    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00 filterror =  16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 minpoll = 6, maxpoll = 10   show ntp status Use this command to display the status of NTP Router#show ntp status Clock is synchronized, stratum 8, reference is 127.127.1.1 nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**24 reference time is D461D902.5B2530A4 (12:52:18.356 PST Thu Nov 29 2012) clock offset is 0.0000 msec, root delay is 0.00 msec root dispersion is 937.73 msec, peer dispersion is 937.67 msec loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000000000 s/s system poll interval is 16, last update was 5 sec ago.   Note: To debug various NTP functions such as authentication validity and ntp events use the command debug ntp.     Related Information Implementing NTPv4 in IPv6 NTPv4 : Common Issues and Troubleshooting Network Time Protocol (NTP) - Home Page ... View more

    Introduction   This document provides information about some of the common issues in NTPv4 and related bug details.   Prerequisite   Basic Understanding about NTP   Common Issues and Related Bug Information   For detailed information and workaround for following issues, refer to Bug Toolkit     NTPv4 takes long time to synchronize   This occurs due to the algorithms in NTPv4. Refer CSCtt04371 for the workaround     NTPv4 takes long time to synchronize with satellite link   CSCti46834 discuss about this issue.     In specific IOS release , NTPv4 have problem in synchronizing when both ntp master and ntp server configured are configured.   Refer CSCte91471 for details on this issue.     NTPv4 server treats NTPv3 client as peer   CSCsw79186 provides a workaround for this issue     NTPv4 facing interoperability issue with NTPv3 when authentication is enabled   CSCti42915 provides more information on this issue .   Related Information Network Time Protocol Version 4(NTPv4) Implementing NTP In IPv6         ... View more

  Introduction This document discuss with an example how to configure Stateful DHCPv6 in Relay mode. Mostly, while configuring the DHCP, the DHCP server may not be connected to clients directly in practical scenarios due to management reasons.In such cases, a DHCP relay agent serves the purpose relaying the messages coming from the clients and server.The DHCPv6 Relay Agent uses Relay forward/Reply messages to relay the messages between Servers and clients. Requirements Understanding of IPv6 Addressing Scheme Implementing DHCPv6 - An Introduction Background   In this configuration example,the router R1 is configured as DHCPv6 server and R2 is configured as Relay Agent. The routers R3 and R4 are configured as DHCPv6Client.   Note: All configurations are tested in a lab environment involving ASR 1000 series router as DHCP server and Cisco 2800 series router as DHCP Clients.   Topology Diagram Summary Steps Server Configuration In Global Configuration Mode ipv6 unciast-routing ipv6 dhcp pool <pool name> address prefix <specify address prefix> lifetime <infinite> <infinite> dns-server <specify the dns server address> domain-name <specify the domain name> exit In Interface Configuration Mode ipv6 address <specify IPv6 Address> ipv6 dhcp server <server name>rapid-commit Relay Agent Configuration In Global Configuration Mode enable configure terminal ipv6 unicast-routing   In Interface Configuration Mode   In DHCPv6 server Facing Interface: ipv6 address autoconfig ipv6 enable exit In Clients Facing Interface ipv6 address <specify IPv6 address> ipv6 dhcp relay destination <specify destination IPv6 address><interface type>   Note: Specify a destination address to which client packets are forwarded and enables DHCPv6 relay service on the interface. Client Configuration In Global Configuration Mode enable configure terminal ipv6 unicast-routing ipv6 nd route-owner In Interface Configuration Mode ipv6 address dhcp rapid commit ipv6 enable ipv6 nd autoconfig prefix ipv6 nd autoconfig default-route exit Configuration   DHCPv6 Server DHCPv6 Relay Agent DHCPv6 Client ! version 15.0 ! hostname R1 ! ipv6 unicast-routing ipv6 cef ipv6 dhcp pool test address prefix 2001:DB8:11::/64 lifetime infinite infinite dns-server AAAA:BBBB:FE10::100 dns-server 2001:DB8::5 domain-name example.com ! ! ! interface FastEthernet1/0 no ip address duplex auto speed auto ipv6 address 2001:DB8:10::1/64 ipv6 dhcp server test ! ! ! ipv6 route 2001:DB8:11::/64 2001:DB8:10:0:C804:1AFF:FEAC:1C ! ! end ! version 15.0 ! hostname R2 ! ipv6 unicast-routing ipv6 cef ! ! interface FastEthernet1/0 no ip address duplex auto speed auto ipv6 address autoconfig ipv6 enable ! ! interface FastEthernet1/1 no ip address duplex auto speed auto ipv6 address 2001:DB8:11::2/64 ipv6 enable ipv6 dhcp relay destination 2001:DB8:10::1 FastEthernet1/0 ! ! ! end ! version 15.0 ! hostname R3/hostname R4 ! ipv6 nd route-owner ipv6 unicast-routing ipv6 cef ! ! interface FastEthernet1/0 no ip address duplex auto speed auto ipv6 address dhcp rapid-commit ipv6 enable ipv6 nd autoconfig prefix ipv6 nd autoconfig default-route ! ! ! end   Note:  Static route to reach the clients (client prefix 2001:db8:11::/64) is added in the DHCPv6 Server so that it can reach clients Under Client configuration The command ipv6 nd route-owner inserts Neighbor Discovery-learned routes into the routing table with "ND" status and enables ND autoconfiguration behavior.This command is configured in Global Configuration mode .   Enabling the command ipv6 nd autoconfig prefix in the interface configuration mode, uses Neighbor Discovery to install all valid on-link prefixes from RAs received on the interface.   To allow Neighbor Discovery to install a default route to the Neighbor Discovery-derived default router , use the command  ipv6 nd autoconfig default-route in the interface configuration mode     Verify Commands   show ipv6 route   In client routers R3 and R4 default route is installed for the ND derived default router.Use this command show ipv6 route to check the routing table.    R3#show ipv6 route IPv6 Routing Table - default - 5 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route        B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP        I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary        D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery        O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2        ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 ND  ::/0 [2/0]      via FE80::C804:1AFF:FEAC:1D, FastEthernet1/0 ND  2001:DB8:11::/64 [2/0]      via FastEthernet1/0, directly connected LC  2001:DB8:11:0:209E:3F6C:3900:7602/128 [0/0]      via FastEthernet1/0, receive ND  2001:DB8:11:0:F145:5C6F:3658:7DB6/128 [2/0]      via FastEthernet1/0, directly connected L   FF00::/8 [0/0]      via Null0, receive show ipv6 dhcp pool   To display the DHCPv6 pool information, in the DHCPv6 server use this command. The output shows that the number of active clients is 2 and  also displays other configuration parameter information, such as domain  name server address and preferred life time information.   R1#show ipv6 dhcp pool DHCPv6 pool: test   Address allocation prefix: 2001:DB8:11::/64 valid 4294967295 preferred 4294967295 (2 in use, 0 conflicts)   DNS server: AAAA:BBBB:FE10::100   DNS server: 2001:DB8::5   Domain name: example.com   Active clients: 2 show ipv6 dhcp binding   To display the information information about the clients, which includes their DUIDs, IAPDs, prefixes, and preferred and valid lifetimes.   R1#sh ipv6 dhcp bin Client: FE80::C805:FFF:FE84:1C   DUID: 00030001CA050F840000   Username : unassigned   IA NA: IA ID 0x00040001, T1 43200, T2 69120     Address: 2001:DB8:11:0:F145:5C6F:3658:7DB6             preferred lifetime INFINITY, , valid lifetime INFINITY, Client: FE80::C806:FFF:FE84:1C   DUID: 00030001CA060F840000   Username : unassigned   IA NA: IA ID 0x00040001, T1 43200, T2 69120     Address: 2001:DB8:11:0:209E:3F6C:3900:7602             preferred lifetime INFINITY, , valid lifetime INFINITY, show ipv6 dhcp interface This command shows that interface Fa1/1 is configured in Relay Mode and displays the relay destination to which  messages from clients should be forwarded.   R2#show ipv6 dhcp interface FastEthernet1/1 is in relay mode   Relay destinations:     2001:DB8:10::1 via FastEthernet1/0 The configuration on the client's side can be verified using the same command in router R3 and R4.   R4#show ipv6 dhcp interface FastEthernet1/0 is in client mode   Prefix State is IDLE   Address State is OPEN   Renew for address will be sent in 06:26:48   List of known servers:     Reachable via address: FE80::C804:1AFF:FEAC:1D     DUID: 00030001CA031AAC0000     Preference: 0     Configuration parameters:       IA NA: IA ID 0x00040001, T1 43200, T2 69120         Address: 2001:DB8:11:0:F145:5C6F:3658:7DB6/128                 preferred lifetime INFINITY, valid lifetime INFINITY       DNS server: AAAA:BBBB:FE10::100       DNS server: 2001:DB8::5       Domain name: example.com       Information refresh time: 0   Prefix Rapid-Commit: disabled   Address Rapid-Commit: disabled   R3#show ipv6 dhcp interface FastEthernet1/0 is in client mode   Prefix State is IDLE   Address State is OPEN   Renew for address will be sent in 06:11:30   List of known servers:     Reachable via address: FE80::C804:1AFF:FEAC:1D     DUID: 00030001CA031AAC0000     Preference: 0     Configuration parameters:       IA NA: IA ID 0x00040001, T1 43200, T2 69120         Address: 2001:DB8:11:0:209E:3F6C:3900:7602/128                 preferred lifetime INFINITY, valid lifetime INFINITY       DNS server: AAAA:BBBB:FE10::100       DNS server: 2001:DB8::5       Domain name: example.com       Information refresh time: 0   Prefix Rapid-Commit: disabled   Address Rapid-Commit: enabled   Ping   You can check the connectivity between the DHCPv6 server and Clients using the ping command   R1#ping 2001:DB8:11:0:209E:3F6C:3900:7602 (Pinging Client 1 R3 from DHCPv6 Server) Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:11:0:209E:3F6C:3900:7602, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 24/66/120 ms R1#ping 2001:DB8:11:0:F145:5C6F:3658:7DB6(Pinging Client 2 R4 from DHCPv6 Server)   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:11:0:F145:5C6F:3658:7DB6, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 0/113/400 ms   Now ping the DHCPv6 server address from the clients R3 and R4.   R3#ping 2001:db8:10::1 (DHCPv6 server Fa1/0 Interface IPv6 address)   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:10::1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 8/48/168 ms   R4#ping 2001:db8:10::1   Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:10::1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 8/80/140 ms   References Part 1: Implementing DHCPv6 - Stateful DHCPv6 Part 2: Implementing DHCPv6 - Stateless DHCPv6 Implementing DHCP for IPv6 IP Version 6 (IPv6) - Cisco Systems Cisco IOS IPv6 Command Reference IPv6 - Frequently Asked Questions Routing Information Protocol ... View more

    Introduction   This document explains the command show ip ospf traffic in OSPFv2 and OSPFv3. The command show ip ospf traffic helps in troubleshooting the OSPF process in more efficient way by displaying the detailed traffic statistics for the OSPF network.   The OSPF traffic statistics are collected and displayed to include the following information:    OSPF Hello input queue and OSPF process queue status and statistics. Global OSPF traffic statistics. Per-OSPF-interface traffic statistics. Per-OSPF-process traffic statistics.   In case of instability in a OSPF network, the OSPF process queue status and its statistical information can help us to determine how much traffic can be sent to OSPF i.e. the amount of traffic handled by and OSPF process can be determined with this output.   Also the OSPF packet header errors and LSA errors statistics help in having a record of different types of errors found in the OSPF packets.     In case of typical local network environments which has slow links and frequent topology changes occurs, you can monitor the amount of  traffic control exchanged between the OSPF process.   Show IP Traffic In OSPFv2   To display the OSPF traffic statistics in a typical OSPFv2 network, use the command show ip ospf traffic   R1#show ip ospf traffic   OSPF statistics:   Last clearing of OSPF traffic counters never     Rcvd: 640 total, 0 checksum errors         617 hello, 3 database desc, 1 link state req         15 link state updates, 4 link state acks     Sent: 636 total         618 hello, 2 database desc, 1 link state req         7 link state updates, 8 link state acks                OSPF Router with ID (3.3.3.3) (Process ID 1)   OSPF queue statistics for process ID 1:                      InputQ     UpdateQ    OutputQ   Limit            0          200        0   Drops            0          0          0   Max delay [msec] 4          0          0   Max size         2          2          2     Invalid        0          0          0     Hello          0          0          1     DB des         2          2          1     LS req         0          0          0     LS upd         0          0          0     LS ack         0          0          0   Current size     0          0          0     Invalid        0          0          0     Hello          0          0          0     DB des         0          0          0     LS req         0          0          0     LS upd         0          0          0     LS ack         0          0          0     Interface statistics:        Interface GigabitEthernet0/1   Last clearing of interface traffic counters never   OSPF packets received/sent   Type          Packets              Bytes   RX Invalid    0                    0   RX Hello      618                  29664   RX DB des     3                    136   RX LS req     1                    36   RX LS upd     15                   1164   RX LS ack     4                    236   RX Total      641                  31236     TX Failed     0                    0   TX Hello      619                  49516   TX DB des     2                    148   TX LS req     1                    68   TX LS upd     7                    564   TX LS ack     8                    772   TX Total      637                  51068   OSPF header errors   Length 0, Auth Type 0, Checksum 0, Version 0,   Bad Source 0, No Virtual Link 0, Area Mismatch 0,   No Sham Link 0, Self Originated 0, Duplicate ID 0,   Hello 0, MTU Mismatch 0, Nbr Ignored 0,   LLS 0, Unknown Neighbor 0, Authentication 0,   TTL Check Fail 0   OSPF LSA errors   Type 0, Length 0, Data 0, Checksum 0     Summary traffic statistics for process ID 1:   OSPF packets received/sent     Type          Packets              Bytes   RX Invalid    0                    0   RX Hello      618                  29664   RX DB des     3                    136   RX LS req     1                    36   RX LS upd     15                   1164   RX LS ack     4                    236   RX Total      641                  31236     TX Failed     0                    0   TX Hello      619                  49516   TX DB des     2                    148   TX LS req     1                    68   TX LS upd     7                    564   TX LS ack     8                    772   TX Total      637                  51068   OSPF header errors   Length 0, Auth Type 0, Checksum 0, Version 0,   Bad Source 0, No Virtual Link 0, Area Mismatch 0,   No Sham Link 0, Self Originated 0, Duplicate ID 0,   Hello 0, MTU Mismatch 0, Nbr Ignored 0,   LLS 0, Unknown Neighbor 0, Authentication 0,   TTL Check Fail 0   OSPF LSA errors   Type 0, Length 0, Data 0, Checksum 0   Note: You can view the OSPF traffic for a specific interface by giving the keyword show ipv6 ospf [process-id] traffic[interface-type interface-number]            Use the command to Clear IPv6 OSPF traffic   to clear the counters     Show IPv6 OSPF Traffic In OSPFv3   R1#show ipv6 ospf traffic   OSPFv3 statistics:   Last clearing of OSPFv3 traffic counters never     Rcvd: 18 total, 0 checksum errors         11 hello, 3 database desc, 0 link state req         2 link state updates, 2 link state acks         0 LSA ignored     Sent: 17 total, 0 failed         11 hello, 2 database desc, 1 link state req         2 link state updates, 1 link state acks               OSPFv3 Router with ID (3.3.3.3) (Process ID 1)   OSPFv3 queue statistic for process ID 1                      InputQ     UpdateQ    OutputQ   Limit            0          200        0   Drops            0          0          0   Max delay [msec] 0          0          4   Max size         2          2          2     Invalid        0          0          0     Hello          0          0          1     DB des         2          2          1     LS req         0          0          0     LS upd         0          0          0     LS ack         0          0          0   Current size     0          0          0     Invalid        0          0          0     Hello          0          0          0     DB des         0          0          0     LS req         0          0          0     LS upd         0          0          0     LS ack         0          0          0     Interface statistics:       Interface FastEthernet0/1   Last clearing of interface traffic counters never   OSPFv3 packets received/sent   Type          Packets              Bytes   RX Invalid    0                    0   RX Hello      12                   480   RX DB des     3                    244   RX LS req     0                    0   RX LS upd     2                    548   RX LS ack     2                    92   RX Total      19                   1364     TX Failed     0                    0   TX Hello      12                   476   TX DB des     2                    56   TX LS req     1                    112   TX LS upd     2                    188   TX LS ack     1                    256   TX Total      18                   1088   OSPFv3 header errors   Length 0, Checksum 0, Version 0, No Virtual Link 0,   Area Mismatch 0, Self Originated 0, Duplicate ID 0,   Instance ID 0, Hello 0, MTU Mismatch 0,   Nbr Ignored 0, Authentication 0, TTL Check Fail 0,   Discarded 0   OSPFv3 LSA errors   Type 0, Length 0, Data 0, Checksum 0     Summary traffic statistics for process ID 1:   OSPFv3 packets received/sent     Type          Packets              Bytes   RX Invalid    0                    0   RX Hello      12                   480   RX DB des     3                    244   RX LS req     0                    0   RX LS upd     2                    548   RX LS ack     2                    92   RX Total      19                   1364     TX Failed     0                    0   TX Hello      12                   476   TX DB des     2                    56   TX LS req     1                    112   TX LS upd     2                    188   TX LS ack     1                    256   TX Total      18                   1088   OSPFv3 header errors   Length 0, Checksum 0, Version 0, No Virtual Link 0,   Area Mismatch 0, Self Originated 0, Duplicate ID 0,   Instance ID 0, Hello 0, MTU Mismatch 0,   Nbr Ignored 0, Authentication 0, TTL Check Fail 0,   Discarded 0   OSPFv3 LSA errors   Type 0, Length 0, Data 0, Checksum 0   Note: You can view the OSPF traffic for a specific interface by giving the keyword show ipv6 ospf [process-id] traffic[interface-type interface-number]            Use the command to Clear IPv6 OSPF traffic  to clear the counters     Related Information Open Shortest Path First (OSPF) - Home Page OSPF Command Reference ... 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    Introduction This document discuss how to shutdown a single switch in stack remotely from the Telnet session in Cisco Catalyst 3500/3700 series switches.   Core Issue   Lets take an example that you are troubleshooting remotely from the Telnet session and would like to turn off only the 5th switch in the stack. From the remote telnet session, if you issue a reload from the telnet session of the switch the entire  stack will reload since the session you are seeing is the master's  session.   Resolution   To turn off only a specific switch in a stack and to bring the power back on the same switch, use the command power supply <switch-number> on/off.   For example: SWITCH#power supply ?   <1-9>  Switch Number SWITCH#power supply 2 ?   off  Set the internal PS off   on   Set the internal PS on   By using the above the command, the 2nd switch in the stack is power down with Off keyword and is turned on using the On keyword.   Note: This is just a work around to bring a specific switch down in a stack, but it is still best to use the stack cables to unstack the switches. This command basically isolates the switch from the stack.You can check the status of the power supplies for a switch or switch stack by using the command show env power.   Source: https://supportforums.cisco.com/thread/2099061   Related Information Catalyst 3750/3560-E Switch Command Reference   This error indicates that PD is drawing over-current more than allowed/supported per IEEE 802.3af standard. ... View more

    Introduction   This document discuss about the High CPU Utilization on Nexus 5010 and related bug information.   Core Issue   High CPU Utilization on Nexus 5010   Resolution   Intermittent High CPU spikes observed under the show process CPU history is expected normal activity on Cisco Nexus 5000 switch. This brief High CPU utilization could be caused by platform processes and does not affect the normal functioning of the switch.   Using the show process cpu history command on a switch with little traffic would show the following:   switch# show processes cpu history       211122112323122212111111111193211112111152112221112222122112       068760965840725240962130210254094430654360576635870512734431   100                             #                                 90                             #                                 80                             #                                 70                             #                                 60                             #           #                     50                             #           #                     40          #                  #           #                     30     #   ## #  #             ##          #   ##     #          20 ################ ###        ####   ###  #################  #   10 ############################################################       0....5....1....1....2....2....3....3....4....4....5....5....                 0    5    0    5    0    5    0    5    0    5                     CPU% per second (last 60 seconds)                         # = average CPU%        1      1   1          1  1                     1      1          906557580987095557477660850989669699968987795968078578509685       500168220197069036851800640710741407559320077351025190708567   100 **      *   **         *  **       **      *    *      **     90 **      *** **         ** ** *  * *** **   * *  * *    ** *   80 **   * *******   * *   ** ****  * *** ***  * * ** * ** ** *   70 **   * *******   * *** ** ***** * ********** ****** ** ****   60 *** ** ********  * ****** ************************* ********   50 ************************************************************   40 ************************************************************   30 *******************************************************#****   20 ############################################################   10 ############################################################       0....5....1....1....2....2....3....3....4....4....5....5....                 0    5    0    5    0    5    0    5    0    5                     CPU% per minute (last 60 minutes)                 * = maximum CPU%   # = average CPU%       323322422222554232222224422225225222222232333522222432225555222222222342       046933526726792664338535533350361672443333087873334873290257433572422603   100                                                                           90                                                                           80                                                                           70                                                                           60             **                               *            **              50       *     **         **    *  *            *     *    ****              40   **  *     *** *      **    *  *          ***     **   ****         **   30 * **  * ** ******   ** **   ** ****     * *****    **  *****   **    **   20 ########################################################################   10 ########################################################################       0....5....1....1....2....2....3....3....4....4....5....5....6....6....7.                 0    5    0    5    0    5    0    5    0    5    0    5    0                      CPU% per hour (last 72 hours)                     * = maximum CPU%   # = average CPU%   Using the show processes cpu sort command, you might see CPU utilization spikes caused by platform processes.   switch# show processes cpu sort | exc 0.0   PID    Runtime(ms)  Invoked   uSecs  1Sec    Process   -----  -----------  --------  -----  ------  -----------   4425         2488   4460919      0   23.5%  statsclient   4296         2343   7178248      0   17.6%  pfma   4404           40  71615766      0    2.0%  gatosusd   CPU util  :   13.9% user,   23.8% kernel,   62.4% idle   switch#   This activity is normal for the switch and does not affect traffic because all traffic is switched by hardware ASICs and not by the CPU. Therefore intermittent high CPU observed in Nexus 5000 is expected and does not affect the normal functioning of the switch. However, the high CPU utilization could also be related to any of the following bugs.   Related Bug Information   For detailed information on the following bugs refer to Bug Toolkit   CSCte81951 - The command show system resources shows incorrect CPU Utilization.   CSCth19083 - Nexus 5000 integrated with a DCNM server, shows High CPU from the SSH process. CSCto47633 -Nexus 5000shows high CPU in wwn_manager when FCOE is enabled. CSCtd04122 -Nexus 5000 reports high CPU via SNMP.   CSCth08102 - The command show system resources shows "nan% user" instead of valid numbers CSCtq05808 - Nexus 5000 reports high CPU utilization due to vlan manager and snmpd processes Related Information Cisco Nexus 5000 Troubleshooting Guide Cisco Nexus 5000 Series Switches-Release Notes         ... View more

  Introduction This document discuss with an example how to configure stateless DHCPv6 in Cisco IOS routers.Stateless DHCPv6 is one of the most convenient method of implementing DHCPv6 in large networks.Stateless DHCPv6 is a combination of Stateless Address Autoreconfiguration (also known as SLAAC) and DHCPv6. In this one or more  IPv6 addresses are assigned to the clients by using SLAAC and additional information i.e configuration parameters such as DNS, NTP are obtained using DHCPv6. This has a significant impact on the DHCP server since the server no longer has to keep track of  the state of any assigned IPv6 addresses to the clients. Also there is no need for state refreshment. In case of large networks which has huge number of hosts attached to it, implementing the stateless DHCPv6 will highly reduce the number of  DHCPv6 messages that are needed for address state refreshment.   Requirements Understanding of IPv6 Addressing Scheme Implementing DHCPv6 - An Introduction Background   In this configuration example,the router R1 is configured as DHCP server while router R2 is configured as DHCPv6Client.   Note: All configurations are tested in a lab environment involving ASR 1000 series router as DHCP server and Cisco 2800 series router as DHCP Clients.   Topology Diagram Summary Steps Server Configuration In Global Configuration Mode ipv6 unicast-routing ipv6 dhcp pool <pool name> dns-server <specify the dns server address> domain-name <specify the domain name> exit In Interface Configuration Mode ipv6 address <specify IPv6 Address> ipv6 nd other-config-flag ipv6 dhcp server test rapid-commit Client Configuration In Global Configuration Mode enable configure terminal ipv6 unicast-routing In Interface Configuration Mode ipv6 address autoconfig ipv6 enable exit   Configuration   DHCPv6 Server DHCPv6 Client ! version 15.1 ! hostname R1 ! ipv6 unicast-routing ipv6 dhcp pool test dns-server AAAA:BBBB:10FE:100::15 dns-server 2010:AA01::15 domain-name example.com ! ! interface GigabitEthernet0/0/1 ipv6 address 2010:AA01:10::2/64 ipv6 nd other-config-flag ipv6 dhcp server test rapid-commit ! ! end ! version 15.0 ! hostname R2 ! ipv6 unicast-routing ipv6 cef ! ! interface FastEthernet0/1 ipv6 address autoconfig ipv6 enable ! end   Note: Note that in the above configuration, the DHCP server is not configured with any address prefix but only with DNS information. Similarly in the client side is configured to obtain the IPv6 address automatically using the SLAAC. Verify Commands debug ipv6 dhcp detail   To display the detailed information about DHCP for IPv6 message decoding use this command. The below output shows the detailed message decoding at the client side.   R2#debug ipv6 dhcp detail *Oct 29 15:14:03.195: IPv6 DHCP: Sending INFORMATION-REQUEST to FF02::1:2 on FastEthernet0/1 *Oct 29 15:14:03.195: IPv6 DHCP: detailed packet contents *Oct 29 15:14:03.195:   src FE80::224:14FF:FE57:6451 *Oct 29 15:14:03.195:   dst FF02::1:2 (FastEthernet0/1) *Oct 29 15:14:03.195:   type INFORMATION-REQUEST(11), xid 5776019 *Oct 29 15:14:03.199:   option ELAPSED-TIME(8), len 2 *Oct 29 15:14:03.199:     elapsed-time 0 *Oct 29 15:14:03.199:   option CLIENTID(1), len 10 *Oct 29 15:14:03.199:     00030001002414576450 *Oct 29 15:14:03.199:   option ORO(6), len 6 *Oct 29 15:14:03.199:     DNS-SERVERS,DOMAIN-LIST,INFO-REFRESH *Oct 29 15:14:03.199: IPv6 DHCP: DHCPv6 changes state from IDLE to INFORMATION-REQUEST (STATELESS) on FastEthernet0/1 *Oct 29 15:14:03.199: IPv6 DHCP: Received REPLY from FE80::D68C:B5FF:FE2E:E101 on FastEthernet0/1 *Oct 29 15:14:03.203: IPv6 DHCP: detailed packet contents *Oct 29 15:14:03.203:   src FE80::D68C:B5FF:FE2E:E101 (FastEthernet0/1) *Oct 29 15:14:03.203:   dst FE80::224:14FF:FE57:6451 (FastEthernet0/1) *Oct 29 15:14:03.203:   type REPLY(7), xid 5776019 *Oct 29 15:14:03.203:   option SERVERID(2), len 10 *Oct 29 15:14:03.203:     00030001D48CB52EE100 *Oct 29 15:14:03.203:   option CLIENTID(1), len 10 *Oct 29 15:14:03.203:     00030001002414576450 *Oct 29 15:14:03.203:   option DNS-SERVERS(23), len 32 *Oct 29 15:14:03.203:     AAAA:BBBB:10FE:100::15 *Oct 29 15:14:03.203:     2010:AA01::15 *Oct 29 15:14:03.203:   option DOMAIN-LIST(24), len 13 *Oct 29 15:14:03.203:     example.com *Oct 29 15:14:03.203: IPv6 DHCP: Adding server FE80::D68C:B5FF:FE2E:E101 *Oct 29 15:14:03.203: IPv6 DHCP: Processing options *Oct 29 15:14:03.203: IPv6 DHCP: Configuring DNS server AAAA:BBBB:10FE:100::15 *Oct 29 15:14:03.203: IPv6 DHCP: Configuring DNS server 2010:AA01::15 *Oct 29 15:14:03.203: IPv6 DHCP: Configuring domain name example.com *Oct 29 15:14:03.203: IPv6 DHCP: DHCPv6 changes state from INFORMATION-REQUEST to IDLE (REPLY_RECEIVED) on FastEthernet0/1 show ipv6 dhcp interface This command shows that interface Fa0/0 is configured in client  mode and also shows the details of the DNS server address and the domain  name that it received from the DHCP server.   R2#show ipv6 dhcp interface FastEthernet0/1 is in client mode   Prefix State is IDLE (0)   Information refresh timer expires in 23:43:01   Address State is IDLE   List of known servers:     Reachable via address: FE80::D68C:B5FF:FE2E:E101     DUID: 00030001D48CB52EE100     Preference: 0     Configuration parameters:       DNS server: AAAA:BBBB:10FE:100::15       DNS server: 2010:AA01::15       Domain name: example.com       Information refresh time: 0   Prefix Rapid-Commit: disabled   Address Rapid-Commit: disabled show ipv6 dhcp pool   To display the DHCPv6 pool information, in the DHCPv6 server use this command. The output shows that the  number of active clients is 1 and  also displays other configuration  parameter information, such as domain  name server address and preferred  life time information.   R1#show ipv6 dhcp pool DHCPv6 pool: test   DNS server: AAAA:BBBB:10FE:100::15   DNS server: 2010:AA01::15   Domain name: example.com   Active clients: 0   Note: In th e above output, the DHCP pool has only the DNS information and there is no IP address assignment. References Part 1: Implementing DHCPv6 - Stateful DHCPv6 Implementing DHCP for IPv6 IP Version 6 (IPv6) - Cisco Systems Cisco IOS IPv6 Command Reference IPv6 - Frequently Asked Questions Routing Information Protocol ... View more