[j-nsp] What is this ethernet switching trace telling us?

[Gavin Henry]

Is this a server connected via two ports?

Sent from my iPad 2

On 7 Jun 2013, at 23:12, John Neiberger <jneiberger at gmail.com> wrote:

> Also, another interesting thing about this is that the output of "show
> ethernet mac-learning-log" stops at April 13th. I have no idea why. If a
> MAC address were jumping around, we'd see it in the MAC learning log...if
> it were up to date. What would cause a Juniper switch to stop logging to
> the MAC learning log?
>
> By the way, this is an EX4200 running 10.4R6.5.
>
>
> On Fri, Jun 7, 2013 at 4:07 PM, John Neiberger <jneiberger at gmail.com> wrote:
>
>> We're trying to troubleshoot an odd issue and this log output makes it
>> appear that a MAC address is flipping between interfaces. There are other
>> interfaces involved later in the logs. I'm starting to think this isn't
>> telling us what we think it's telling us. Does this indicate that the MAC
>> address really is being learned from multiple interfaces? The confusing
>> thing about the logs is the mention of l3nh. Is that layer three next hop?
>> If so, why are we seeing that in ethernet-level trace options and what is
>> the significance?
>>
>> I'm a little confused. Here is an example:
>>
>> Jun  4 13:07:22.953201 Attempt to add vlan sbc-core mac 00:08:25:fa:3c:82,
>> ifname ge-0/0/6.0, pnac_status 0, 0
>> Jun  4 13:07:22.953312 vlan sbc-core mac 00:08:25:fa:3c:82 (tag 40), iif =
>> ge-0/0/6.0: present in FDB
>> Jun  4 13:07:22.953374 (3, 00:08:25:fa:3c:82) next-hop index change [1344
>> -> 1328]
>> Jun  4 13:07:22.953562 KRT enqueue FDB (3, 00:08:25:fa:3c:82) nh-index 1328
>> Jun  4 13:07:22.953712 krt_dequeue: type FDB op change 3,
>> 00:08:25:fa:3c:82 Direct nh 1328
>> Jun  4 13:07:22.954372 l3nh_fdb_notify: FDB CHANGE vlan <sbc-core> mac
>> 00:08:25:fa:3c:82
>> Jun  4 13:21:18.041160 Attempt to add vlan sbc-core mac 00:08:25:fa:3c:82,
>> ifname ge-0/0/5.0, pnac_status 0, 0
>> Jun  4 13:21:18.041271 vlan sbc-core mac 00:08:25:fa:3c:82 (tag 40), iif =
>> ge-0/0/5.0: present in FDB
>> Jun  4 13:21:18.041332 (3, 00:08:25:fa:3c:82) next-hop index change [1328
>> -> 1327]
>> Jun  4 13:21:18.041670 Attempt to add vlan sbc-core mac 00:08:25:fa:3c:82,
>> ifname ge-0/0/6.0, pnac_status 0, 0
>> Jun  4 13:21:18.041767 vlan sbc-core mac 00:08:25:fa:3c:82 (tag 40), iif =
>> ge-0/0/6.0: present in FDB
>> Jun  4 13:21:18.041807 (3, 00:08:25:fa:3c:82) next-hop index change [1327
>> -> 1328]
>> Jun  4 13:21:18.041962 KRT enqueue FDB (3, 00:08:25:fa:3c:82) nh-index 1328
>>
>> It looks to me like the MAC address is jumping around. What do you think?
>>
>> Thanks,
>> John
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