ipv6 and freebsd

Steve Bertrand steve at ibctech.ca
Thu Feb 12 06:20:55 PST 2009

gahn wrote:
> Thanks Steve:
> the router that sending RA is juniper and the protocol router-advertisement has been activated:
> ga at lab_1> show interfaces fe-0/0/3
> ...
>   Logical interface fe-0/0/3.170 (Index 70) (SNMP ifIndex 59) 
> ...
>       Addresses, Flags: Is-Preferred
>         Destination: fe80::/64, Local: fe80::214:f600:aa2c:d403
>       Addresses, Flags: Is-Preferred Is-Primary
>         Destination: fec0:10:5::/64, Local: fec0:10:5:0:214:f600:aa2c:d403

fec0::/10 was deprecated per RFC3879. Perhaps the Juniper unit is
obeying this and just not sending the prefix in the advertisement?

Everything else looks good, so lets test that possibility (as remote as
it is). Take your tcpdump one step further:

> lab# tcpdump -n -i bge1 ip6
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on bge1, link-type EN10MB (Ethernet), capture size 96 bytes
> 17:55:44.027565 IP6 fe80::214:f600:aa2c:3c03 > ff02::1: ICMP6, router advertisement, length 24
> 18:02:46.283353 IP6 fe80::214:f600:aa2c:d403 > ff02::1: ICMP6, router advertisement, length 24

# tcpdump -n -i bge1 -s 0 -w /path/to/file.pcap ip6

After a time of that running (there won't be any STDOUT output), stop
the capture, and open the file in Wireshark. (I've never figured out
how to get tcpdump to read the data portion of the packets from a file).

With the -s0, it will capture the headers and the data of each packet,
so you should be able to tell whether the RA announcements do actually
contain the prefix you are trying to get configured.

Something that I should have asked from the get-go...do you have any
sort of firewall running on the box?

I'll set this up in my lab here today. Although we don't have any
Juniper units, I'll see if I can recreate the problem with Cisco
hardware. You may also want to test using a non-deprecated address
space. The documentation address may work for instance.


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