11-27-2012 10:30 PM - edited 03-01-2019 04:52 PM
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.
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.
In Global Configuration Mode
In Interface Configuration Mode
In Global Configuration Mode
In Interface Configuration Mode
In DHCPv6 server Facing Interface:
In Clients Facing Interface
Note: Specify a destination address to which client packets are forwarded and enables DHCPv6 relay service on the interface.
In Global Configuration Mode
In Interface Configuration Mode
DHCPv6 ServerDHCPv6 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:
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
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
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
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,
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
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
Routing Information Protocol
very good explanation.
Hi, very interesting.
One question : if I'm not wrong, in this setup dhcp server is releasing only dns address and domain name, while addres is get by the client through nd from the router.
I'm trying to test an environment where dhcp offer also the ipv6 address to the client but for now it is not working.
Do you have a similar setup to share ?
thanks
Stefano
May i have the file? Or if possible, can you send the file to my email? or send the download link by replying to my comment
Thanks!
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