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Bittrance
Asked: 2011-12-17 16:16:31 +0800 CST

Linux does not get IPv6 default gateway from Cisco ASA5510 on autoconf

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My ASA 5510 has the following configuration for an interface. My Ubuntu box (2.6.35) connected to this network will correctly autoconf an IPv6 address, but it will not set a default route. 

interface Ethernet0/0.10
 vlan 10
 no shutdown
 nameif inside
 security-level 100
 ip address 172.18.0.1 255.255.254.0
 ipv6 address REMOVED:1::1/64
 ipv6 nd prefix REMOVED:1::/64
 ipv6 nd ra-interval 120
 ipv6 enable

Thus, ping6 REMOVED:1::1 works fine and if I manually add a default route for IPv6 it works fine.

The resulting router advertisement looks like this:

01:06:42.253895 IP6 (class 0xe0, hlim 255, next-header ICMPv6 (58) payload length: 64) fe80::21c:58ff:fed3:ea36 > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 64
        hop limit 64, Flags [none], pref medium, router lifetime 1800s, reachable time 0s, retrans time 1000s
          source link-address option (1), length 8 (1): 00:1c:58:d3:ea:36
            0x0000:  001c 58d3 ea36
          mtu option (5), length 8 (1):  1500
            0x0000:  0000 0000 05dc
          prefix info option (3), length 32 (4): REMOVED:1::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s
            0x0000:  40c0 0027 8d00 0009 3a80 0000 0000 XXXX
            0x0010:  XXXX XXXX 0001 0000 0000 0000 0000

How come I do not get a default gateway set?

cisco-asa ipv6 linux-networking

2 Answers

  1. You can debug the process on the ubuntu box (a bit) with:

    rdisc6 -v eth0

    See if the advertisment matches what you expect.

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  2. Best Answer

    For unclear reasons, this problem no longer persists. It may be that it disappeared on Ubuntu upgrade.

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