[c-nsp] Bug with IOS-XR and SPAN ports?

[Hank Nussbacher]

On 24/11/2016 16:33, James Bensley wrote:
> On 9 November 2016 at 21:24, Hank Nussbacher <hank at efes.iucc.ac.il> wrote:
>> We upgraded our AS9010 this morning from 5.1.3 to 5.3.3 and encountered
>> an issue with SPAN ports.
>>
>> Our SPAN port config looks like this:
>> monitor-session No1 ethernet
>>  destination interface TenGigE0/1/1/4
>> !
>> monitor-session No2 ethernet
>>  destination interface TenGigE0/1/1/5
>> !
>> interface GigabitEthernet0/1/0/10
>>  monitor-session No1 ethernet
>> !
>> interface TenGigE0/0/1/2
>>  monitor-session No2 ethernet
>> !
>> interface TenGigE0/1/1/7
>>  monitor-session No1 ethernet
>> !
>> interface TenGigE0/1/1/7.100
>>  monitor-session No1 ethernet
>> !
>> interface TenGigE0/1/1/7.333
>>  monitor-session No1 ethernet
>> !
>> interface TenGigE0/1/1/7.667
>>  monitor-session No1 ethernet
>>
>> On IOS-XR 5.1.3 - no problem with the above config.  On IOS-XR 5.3.3 we
>> found that when the destination SPAN port gets overloaded, in addition
>> to dropping the pkt destined to the destination port (no big deal),
>> IOS-XR also silently drops the pkt from the port that was being SPANed
>> (yes, a big deal).  Has anyone encountered this, or has a workaround or
>> a Cisco bugid?
>>
>> Thanks,
>> Hank
> Hi Hank,
>
> Did you get to the bottom of this? This could be quite a problem. Did
> you find out if it was a bug per chance?

We have had a TAC case open for a month and they were able to reproduce
it just once, where we have been hit by it now twice.
There seems to be some unknown threshold that needs to be crossed before
the ingress SPANned port starts losing pkts silently.
We might very well have to downgrade because of this.

-Hank

>
> Cheers,
> James.
>