That's good to know. We actually have several Gbps of multicast video running over these boxes. Based on that, I suspect that we'll do that change some other night unless I have plenty of time tonight to deal with it.
Thanks for everyone's input. That helps me out a lot! John On Tue, Sep 21, 2010 at 1:27 PM, Benjamin Lovell <belov...@cisco.com> wrote: > The primary thing to worry about here is the mcast packet rate not number of > mroutes. Replication change will cause all mcast packets to be punted to CPU > for a short period(few 100 msec or so). I have seen this go badly under the > following conditions. > > 1) High rate of mcast traffic. few Gigs per sec. > 2) BFD will tight timers in the 750msec range. > > When mcast started getting punted the CPU spiked to the moon. Input queues > got smashed. BFD and therefor OSPF dropped. RPF interfaces changed and it > took almost 30min for the box to calm back down. > > If you have a moderate to high mcast packet rate I would not count on this > being a hitless change. > > -Ben > > > On Sep 21, 2010, at 3:01 PM, John Neiberger 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 <tstev...@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 <jeff...@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 <jneiber...@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? >>>>>> _______________________________________________ >>>>>> cisco-nsp mailing list cisco-...@puck.nether.net >>>>>> >>>>>> <https://puck.nether.net/mailman/listinfo/cisco-nsp>https://puck.nether.net/mailman/listinfo/cisco-nsp >>>>>> archive at >>>>>> <http://puck.nether.net/pipermail/cisco-nsp/>http://puck.nether.net/pipermail/cisco-nsp/ >>>>>> >>>>> >>>> >>>> _______________________________________________ >>>> cisco-nsp mailing list cisco-...@puck.nether.net >>>> >>>> <https://puck.nether.net/mailman/listinfo/cisco-nsp>https://puck.nether.net/mailman/listinfo/cisco-nsp >>>> archive at >>>> <http://puck.nether.net/pipermail/cisco-nsp/>http://puck.nether.net/pipermail/cisco-nsp/ >>> >>> >>> >>> >>> Tim Stevenson, tstev...@cisco.com >>> Routing & Switching CCIE #5561 >>> Distinguished Technical Marketing Engineer, Cisco Nexus 7000 >>> Cisco - http://www.cisco.com >>> IP Phone: 408-526-6759 >>> ******************************************************** >>> The contents of this message may be *Cisco Confidential* >>> and are intended for the specified recipients only. >>> >>> >>> >> >> _______________________________________________ >> cisco-nsp mailing list cisco-...@puck.nether.net >> https://puck.nether.net/mailman/listinfo/cisco-nsp >> archive at http://puck.nether.net/pipermail/cisco-nsp/ > > _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
