Greetings, We've recently run into a problem with a home-grown application that uses MSMQ 'Reliable Multicast' (ie PGM) to communicate.
Long story cut short, PGM relies on a set of packets called SPMs all of which have the IP Option 'Router Alert' set. This is one of those things that seem like a fantastic idea on paper, but... During busy periods we're seeing thousands of these packets per second. As each individual packet has to be inspected by the CPU (this isn't just software forwarding, this is full-on to-the-CPU-for-full-examination punting) they melt under the pressure (90%+ CPU and OSPF/HSRP/BGP starts flapping). We're running with Cat4500s, with a combination of Sup4/5s. Speaking to Cisco this is essentially expected behaviour as the forwarding capacity for packets needing CPU examination is in the very low thousands. Has anyone run into this problem before? If so, how did you solve it? Our options seem to be one of a) Make MSMQ not set the alert bit as we don't require it anyway (doesn't seem to be possible), b) Make the Ciscos ignore router alert bits (not terrible, but might affect non-PGM traffic and I'm not even sure this is easily achievable) and c) Stick in a platform that can handle this better than the Ciscos (not convinced this is easy either as it's a CPU thing not a forwarding plane thing). Thanks, Ras _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
