topic Re: ICX stack stops responding to IPv6 Neighbor Solicitations in ICX Switches

ICX stack stops responding to IPv6 Neighbor Solicitations

kpfleming — Thu, 13 May 2021 11:25:51 GMT

I'm working on replacing the core of my network with a stack of 7150-C12P units running the layer 3 image. So far things have been working pretty well, but I've run into a problem. I'm running the 08.0.95caT213 release.

Specifically, I have one interface setup for route-only traffic to the existing network core, and it has both IPv4 and IPv6 addressing enabled (plus there is OSPF running for both protocols). Interface config is:


SSH@ICX7150-C12 Router>show running-config interface ethernet 1/1/12
interface ethernet 1/1/12
 route-only
 ip address 192.168.100.2 255.255.255.0
 ip ospf area 0
 ip ospf network point-to-point
 ipv6 address fd80:ae6b:5f43:100::2/64
 ipv6 enable
 ipv6 ospf area 0
 ipv6 nd suppress-ra
!
SSH@ICX7150-C12 Router>show ipv6 interface ethernet 1/1/12
Interface e 1/1/12 is up, line protocol is up
  IPv6 is enabled, link-local address is fe80::7aa6:e1ff:fe3e:842e [Preferred]
  Global unicast address(es):
    fd80:ae6b:5f43:100::2 [Preferred],  subnet is fd80:ae6b:5f43:100::/64
  Joined group address(es):
    ff02::6
    ff02::5
    ff02::1:ff00:2
    ff02::1:ff3e:842e
    ff02::16
    ff02::d
    ff02::1:ff00:0
    ff02::2
    ff02::1
  Port belongs to VRF: default-vrf
  MTU is 1500 bytes 
  ICMP redirects are disabled,  Router preference: Medium
  ND DAD is enabled, number of DAD attempts: 3
  ND reachable time is 30000 miliseconds
  ND stale time is 7200000 miliseconds
  ND retransmit interval is 1000 miliseconds
  ND advertised reachable time is 0 seconds
  ND advertised retransmit interval is 0 miliseconds
  ND router advertisements are sent every 272 seconds             
  ND router advertisements live for 1800 seconds
  Hosts use stateless autoconfig for addresses
  No Inbound Access List Set
  No Outbound Access List Set
  OSPF enabled

(OSPF point-to-point is not enabled for IPv6 because the router on the other end of the link does not support it).

This works for some period of time, doesn't seem to be a consistent amount of time, and then stops... when it stops, if I watch traffic on that link from the other end, I see IPv6 NS packets being sent for the address fd80:ae6b:5f43:100::2 but the ICX does not respond. Even rebooting the system doesn't help; the ICX still doesn't respond to NS from the other router.

Can anyone suggest additional troubleshooting or configuration I could try?

Re: ICX stack stops responding to IPv6 Neighbor Solicitations

kpfleming — Mon, 17 May 2021 10:03:29 GMT

No solution yet, but the ICX started responding again a few days ago, and hasn't stopped since.

Re: ICX stack stops responding to IPv6 Neighbor Solicitations

jijo_panangat — Mon, 17 May 2021 11:29:07 GMT

Hi Kevin,

Could you pls try removing 'ipv6 nd suppress-ra' and check ?

Thanks

Jijo

Re: ICX stack stops responding to IPv6 Neighbor Solicitations

kpfleming — Mon, 17 May 2021 12:25:59 GMT

Yes, if it stops behaving properly again that's the first thing on my list to try.

At the time that this problem occurred there was very little IPv6 traffic on this interface (pretty much just OSPFv3), but now there is more as there are additional devices on the other side of the ICX that are communicating. It is possible that this was somehow related to the lack of activity.

Re: ICX stack stops responding to IPv6 Neighbor Solicitations

jijo_panangat — Mon, 17 May 2021 13:39:56 GMT

ok, Thanks.

You can use 'show ipv6 neighbor' to check the current state of the neighbor as well.

Thanks

Jijo

Re: ICX stack stops responding to IPv6 Neighbor Solicitations

kpfleming — Sat, 11 Sep 2021 18:47:22 GMT

For what it's worth, with no configuration changes at all this symptom has disappeared after upgrading to 09.0.00. It's only been a few hours, and the problem wasn't consistent before, so it will take a few days before I'll be confident that it's actually gone, but this is promising.