Hello everyone,
I decided to put a question on the forum, because I have a problem with simple configuration of network topology using subinterfaces. I've got following topology:
R1, R2, R3 are 3725 routers with IOS 12.4(25).
Configuration of devices is presented below:
R1:
interface FastEthernet0/0
speed 100
full-duplex
ipv6 address 2001:1::2/64
ipv6 route 2001:2::/64 FastEthernet0/0
R2:
interface FastEthernet0/0
no ip address
speed 100
full-duplex
!
interface FastEthernet0/0.1
encapsulation dot1Q 1 native
ipv6 address 2001:1::1/64
ipv6 address FE80::1 link-local
!
interface FastEthernet0/0.2
encapsulation dot1Q 2
ipv6 address 2001:2::1/64
ipv6 address FE80::2 link-local
R3:
interface FastEthernet0/0
speed 100
full-duplex
ipv6 address 2001:2::2/64
ipv6 route 2001:1::/64 FastEthernet0/0
R4:
interface FastEthernet0/0
switchport mode trunk
duplex full
speed 100
!
interface FastEthernet0/1
duplex full
speed 100
!
interface FastEthernet0/2
switchport access vlan 2
duplex full
speed 100
I am not able to ping for example from R1 to R2's subinterface fa0/0.2 and of course to R3, because Neighbor Solicitation messages are received on R2, but no reply is being sent:
R1#ping 2001:2::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:2::1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R2#
*Mar 1 01:18:14.391: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 135
*Mar 1 01:18:15.091: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 135
R2#
*Mar 1 01:18:16.063: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 135
R2#
*Mar 1 01:18:18.195: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 135
*Mar 1 01:18:19.163: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 135
R2#
*Mar 1 01:18:20.271: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 135
The strange thing is that when I change definition of a static route to one with next-hop address it suddently starts to work properly:
R1(config)#ipv6 route 2001:2::/64 2001:1::1
R1#ping 2001:2::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:2::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 368/874/1100 ms
R2#
*Mar 1 01:21:01.735: ICMPv6: Received echo request from 2001:1::2
*Mar 1 01:21:01.735: ICMPv6: Sending echo reply to 2001:1::2
*Mar 1 01:21:01.795: ICMPv6: Received echo request from 2001:1::2
*Mar 1 01:21:01.795: ICMPv6: Sending echo reply to 2001:1::2
*Mar 1 01:21:01.859: ICMPv6: Received echo request from 2001:1::2
*Mar 1 01:21:01.859: ICMPv6: Sending echo reply to 2001:1::2
*Mar 1 01:21:01.923: ICMPv6: Received echo request from 2001:1::2
*Mar 1 01:21:01.923: ICMPv6: Sending echo reply to 2001:1::2
*Mar 1 01:21:01.983: ICMPv6: Received echo request from 2001:1::2
*Mar 1 01:21:01.987: ICMPv6: Sending echo reply to 2001:1::2
R2#
*Mar 1 01:21:06.771: ICMPv6: Received ICMPv6 packet from 2001:1::2, type 136
I am very curious what is the cause of this behavior. Is there any rule that in IPv6 we have to use next-hop address in such situations?
Thank you in advance,
Mateusz
Hello,
Thank you for your reply. It would make sense for me if R2 would not receive any packet, but it receives a request and then does not send any reply to NS sent from R1 as I showed in the example. Path to R2 which is a gateway is seen as directly connected on R1:
R1#sh ipv6 ro
IPv6 Routing Table - 5 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
C 2001:1::/64 [0/0]
via ::, FastEthernet0/0
L 2001:1::2/128 [0/0]
via ::, FastEthernet0/0
S 2001:2::/64 [1/0]
via ::, FastEthernet0/0
L FE80::/10 [0/0]
via ::, Null0
L FF00::/8 [0/0]
via ::, Null0
I'm wondering why R2 cannot respond when its own interface has an address that I want to ping (2001:2::1)
