IPv6 Global Prefix RA question from R1 to R2

Unanswered Question
Mar 13th, 2012

Hello,

I've a questiona about IPv6 Global Prefix RA.

I have 2 routers (r1 and r2) connected via fastethernet0/0 interface.

On the first router i have gone trough the ipv6 set up:

1. I have create a ipv6 address: #ipv6 address 2001:aaa:bbbb:cccc::/64 eui-64

2. told the router that it can route ipv6: #ipv6 unicast-routing

Below is a #show ipv6 interface on R1:

FastEthernet0/0 is up, line protocol is up

  IPv6 is enabled, link-local address is FE80::CA00:10FF:FE84:0

  Global unicast address(es):

    2001:AAA:BBBB:CCCC:CA00:10FF:FE84:0, subnet is 2001:AAA:BBBB:CCCC::/64

  Joined group address(es):

    FF02::1

    FF02::2

    FF02::1:FF84:0

On the second router I have gone trough the ipv6 steps:

1. I have enable ipv6: #ipv6 enable.

I do see that the link-local address has been created: FE80::CA02:10FF:FE84:0

Below is a # show ipv6 interface on R2:

FastEthernet0/0 is up, line protocol is up

  IPv6 is enabled, link-local address is FE80::CA02:10FF:FE84:0

  No global unicast address is configured

  Joined group address(es):

    FF02::1

    FF02::2

    FF02::1:FF84:0

My question is as follows: why doesn't get Router2 the global prefix information in the ipv6 address from Router 1

I do see a RA send from R1 to R2.

R1#

*Mar  1 00:40:37.455: ICMPv6-ND: Sending RA to FF02::1 on FastEthernet0/0

*Mar  1 00:40:37.455: ICMPv6-ND:     MTU = 1500

*Mar  1 00:40:37.455: ICMPv6-ND:     prefix = 2001:AAA:BBBB:CCCC::/64 onlink autoconfig

*Mar  1 00:40:37.455: ICMPv6-ND:             2592000/604800 (valid/preferred)

*Mar  1 00:40:37.455: IPV6: source FE80::CA00:10FF:FE84:0 (local)

*Mar  1 00:40:37.455:       dest FF02::1 (FastEthernet0/0)

*Mar  1 00:40:37.455:       traffic class 224, flow 0x0, len 104+1396, prot 58, hops 255, originating

*Mar  1 00:40:37.455: IPv6: Sending on FastEthernet0/0

R2(config)#

*Mar  1 00:39:42.275: ICMPv6-ND: Received RA from FE80::CA00:10FF:FE84:0 on FastEthernet0/0

What I also see is that R1 is getting RA from R2:

R1#

*Mar  1 00:47:56.199: ICMPv6-ND: Received RA from FE80::CA02:10FF:FE84:0 on FastEthernet0/0

Thank I great advance,

Lino

I have this problem too.
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dancicioiu Tue, 03/13/2012 - 03:53

Hi Lino ,

have you tried on Fa0/0 on R2 : ipv6 address autoconfig.

Dan

Nagendra Kumar ... Tue, 03/13/2012 - 03:59

Hi Lino,

My question is as follows: why doesn't get Router2 the global prefix  information in the ipv6 address from Router 1

You need to configure "ipv6 address autoconfig". When you have it enabled, IPv6 router on receiving RA will get the prefixes with A flag set and will append 64 bit Interface ID.

What I also see is that R1 is getting RA from R2:

Per my understanding, RA is not only for stateless autoconfiguration. SLAAC is one benefit from RA while there are otehr benefits like MAC learning, default router advertisement etc..

Thanks,

Nagendra

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Posted March 13, 2012 at 3:32 AM
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