My understanding of an LTL is a path map for traffic through the switch. In the VSS environment, every multicast stream consumes 3 multicast LTL resources for each VLAN on the switch and another 3 LTL's for each IGMP snooping entry. We had 300+ multicast channels coming in from encoders, then being joined by encryption servers and ICC/error correcting servers. The encryption servers were sending an encrypted multicast stream back into the VSS. We also had another set of servers joining the encrypted streams and generating a PIP stream.
In a stand alone 6509 there are ~30K multicast LTL's available. In the VSS this number drops to ~20 for the two combined 6509's. Our 300+ channels with all of the extra stream for PIP, encryption and ICC etc.. Were using over 19,800 multicast LTL's. There is an LTL threshold of 200 free LTL's. Once you have less than 200 free multicast LTL's available, the switch will disable IGMP snooping and begin to flood multicast out of all ports. This obviously crashes the switch processor. Some commands to see LTL usage: "show platform hardware capacity multicast" "remote command switch show mmls mltl" I hope this information helps. Regards, Brad On 6/17/11 2:50 PM, "Youssef El Fathi" <[email protected]> wrote: >Hello Bradley, > >I would like to have more details about the performance issue you ran with >IP mcast traffic? Can you give me more details. > >Thanks and regards > >Youssef > > >> Message: 8 >> Date: Fri, 17 Jun 2011 08:15:28 -0500 >> From: Bradley Williamson <[email protected]> >> To: Mike G <[email protected]> >> Cc: "[email protected]" <[email protected]> >> Subject: Re: [c-nsp] VSS - Horror stories, show-stoppers, other >> personal experience? >> Message-ID: <[email protected]> >> Content-Type: text/plain; charset="us-ascii" >> >> I just spent the better part of my day splitting a vss. >> >> I think it works well for the most part. Fail over works well. It Is >>easy >> to manage. MEC is nice too. >> >> We tried it in an Multicast environment, and it was too resource limited >> for what we were doing. If you are not doing much multicast (300+ >>channels) >> then it should work well for you. >> >> Sent from my iPad >> >> >_______________________________________________ >cisco-nsp mailing list [email protected] >https://puck.nether.net/mailman/listinfo/cisco-nsp >archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
