[c-nsp] Operational impact of switching from ingress to egress replication mode

[Jeffrey Pazahanick]

FWIW, I had some issues with SRC2 and egress replication..  Might be
specific to the ES20+ cards.

On Tue, Sep 21, 2010 at 2:01 PM, John Neiberger <jneiberger at gmail.com> wrote:
> If I recall correctly, we have over 500 mroutes. I was just speaking
> to a Cisco engineer that works with us about this. I think I'm going
> to save this change until last. We have a lot of etherchannels and we
> want to convert those to routed links with ECMP first, then we'll
> switch over to egress replication. It sounds like we shouldn't have
> more than a couple of seconds of impact.
>
> Thanks!
> John
>
> On Tue, Sep 21, 2010 at 12:46 PM, Tim Stevenson <tstevens at cisco.com> wrote:
>> Hi John,
>> Switching replication modes basically purges the hardware of all mroutes and
>> those will be reprogrammed based on the current software state. It will be
>> potentially disruptive for all mroutes, but the exact amount of traffic
>> loss/blackholing would depend on the rate of each stream at the time, and
>> the overall amount of time it takes to reprogram. For a few 100 mroutes, I
>> would not expect much impact.
>>
>> Hope that helps,
>> Tim
>>
>> At 11:30 AM 9/21/2010, John Neiberger averred:
>>
>>> We're running 12.2(33)SRC2, I believe. It's actually experimental code
>>> and the exact version is overwritten with another code.
>>>
>>> On Tue, Sep 21, 2010 at 12:04 PM, Jeffrey Pazahanick <jeffpaz at gmail.com>
>>> wrote:
>>> > John,
>>> > Having switched back and forth a few times, I never noticed more than
>>> > a 1-2 second outage.
>>> > What version of code are you on?
>>> >
>>> > On Tue, Sep 21, 2010 at 11:59 AM, John Neiberger <jneiberger at gmail.com>
>>> > wrote:
>>> >> We're going to be doing a whole bunch of maintenance tonight during a
>>> >> maintenance window. One of the many things on our plate is to switch
>>> >> from ingress replication mode to egress on some 7600s that have a few
>>> >> hundred multicast routes on them. We know there is going to be at
>>> >> least a minor blip while things settle down after making the change,
>>> >> but I wanted to see if anyone on the list has done this and what the
>>> >> operational impact was. I've heard there will be slight interruption
>>> >> in traffic, but what sort of interruption are we talking about? Are we
>>> >> speaking about a second or two?
>>> >>
>>> >> I'm asking because we're trying to decide if we want to split this out
>>> >> to another night. If the disruption is minor and the risk is low then
>>> >> we'll do it tonight. Otherwise, we might choose to do it on a separate
>>> >> night.
>>> >>
>>> >> Any thoughts?
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>>
>>
>>
>> Tim Stevenson, tstevens at cisco.com
>> Routing & Switching CCIE #5561
>> Distinguished Technical Marketing Engineer, Cisco Nexus 7000
>> Cisco - http://www.cisco.com
>> IP Phone: 408-526-6759
>> ********************************************************
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>>
>>
>