mulitskiy at acedsl
Jul 10, 2012, 8:11 AM
Post #4 of 7
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Re: IOS 15.0 ipv6-related weirdness (fails to fallback to ipv4)
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Heh.
c2800#sh ipv6 interface
VoIP-Null0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::226:99FF:FED0:1290
No Virtual link-local address(es):
No global unicast address is configured
Joined group address(es):
FF02::1
FF02::1:FFD0:1290
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is not supported
ND reachable time is 30000 milliseconds (using 30000)
Don't see any way to disable it. Can't even find any description what it is, but obviously it's
voip-related and this router is indeed sip gateway.
Now I have to make sure that sip servers it's talking to don't publish AAAA, until I manage
to upgrade to something that has it fixed.
Thanks for the hint,
Michael Ulitskiy
On Tuesday 10 July 2012 08:09:43 Matthew Huff wrote:
> > Is "ipv6 enable" configured on any interface at all? What does a "show
> > ipv6 interfaces" say?
> >
> > With ipv6-unicast routing disabled, the router will still function as
> > an
> > ipv6 host if there are any IPv6 configured interfaces. And google
> > returns both an A and AAAA record for google.com.
>
> This was my first thought also, however, the post of:
>
> c2800#sh ipv6 interface brief
> FastEthernet0/0 [up/up]
> unassigned
> FastEthernet0/1 [up/up]
> Unassigned
>
> Appears to disprove that. I would think this is just a bug.
>
>
> ----
> Matthew Huff | 1 Manhattanville Rd
> Director of Operations | Purchase, NY 10577
> OTA Management LLC | Phone: 914-460-4039
> aim: matthewbhuff | Fax: 914-460-4139
>
> > -----Original Message-----
> > From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-
> > bounces [at] puck] On Behalf Of Bruce Pinsky
> > Sent: Monday, July 09, 2012 9:39 PM
> > To: Michael Ulitskiy
> > Cc: cisco-nsp [at] puck
> > Subject: Re: [c-nsp] IOS 15.0 ipv6-related weirdness (fails to fallback
> > to ipv4)
> >
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Michael Ulitskiy wrote:
> > > Hello,
> > >
> > > I have a 2800 router with IOS 15.0(1)M7 with no ipv6 connectivity.
> > > There are no ipv6 addresses configured on any interfaces and i've
> > added:
> > >
> > > no ipv6 cef
> > > no ipv6 unicast-routing
> > >
> > > commands to config.
> > >
> > > Nonetheless when I try to ping google the following happens:
> > >
> > > c2800#ping google.com
> > > Translating "google.com"...domain server (167.206.112.138) [OK]
> > >
> > > Type escape sequence to abort.
> > > Sending 5, 100-byte ICMP Echos to 2607:F8B0:4006:801::1004, timeout
> > is 2 seconds:
> > >
> > > % No valid source address for destination Success rate is 0 percent
> > > (0/1)
> > >
> > > c2800#sh hosts
> > > Default domain is aceinnovative.com
> > > Name/address lookup uses domain service Name servers are
> > > 167.206.112.138, 167.206.7.4
> > >
> > > Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
> > > temp - temporary, perm - permanent
> > > NA - Not Applicable None - Not defined
> > >
> > > Host Port Flags Age Type Address(es)
> > > google.com None (temp, OK) 0 IPv6
> > 2607:F8B0:4006:801::1004
> > >
> > > So when it sees AAAA record it tries to use it (regardless ipv6
> > > routing has been disabled), sees there're no valid ipv6 addresses to
> > > use as source and fails, instead of trying to use alternative
> > > ipv4 addresses. It's also very strange that only IPv6 address has
> > been cached by resolver.
> > > It looks like resolver discards any A record in the presence of AAAA.
> > >
> > > FYI:
> > > c2800#sh ipv6 interface brief
> > > FastEthernet0/0 [up/up]
> > > unassigned
> > > FastEthernet0/1 [up/up]
> > > unassigned
> > >
> > > c2800#sh ipv6 route
> > > IPv6 Routing Table - default - 1 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
> > > L FF00::/8 [0/0]
> > > via Null0, receive
> > >
> > > I wonder if this is a known issue, if there are any workarounds or if
> > I'm missing something?
> >
> >
> > - --
> > =========
> > bep
> >
> >
> >
> > -----BEGIN PGP SIGNATURE-----
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> > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
> >
> > iEYEARECAAYFAk/7h8oACgkQE1XcgMgrtybrxgCgkjn1okrSrVdjNdxya7upf1Sj
> > lfoAoN8ql0aXuchVf1ThxsHcJzL2cxRo
> > =5EFq
> > -----END PGP SIGNATURE-----
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