Multicasting and other LAN best practices

[krabilld1]

Hello,

I am sort of new to networking and would like some information on how to properly implement multicasting and other best practices for a LAN I am responsible for.   I will try to give a little background information and hopefully some of you can help me with some possible sample config information and perhaps additional documentation.  

The following is the type of setup we are using.   At a single location we generally have a Cisco Catalyst 3550-12G switch that we use as our core switch for the location.   We have a few VLANs setup on this switch.   Generally what we are doing is having a VLAN for all PCs and another VLAN for our wireless access points.   In addition we might have an additional VLAN for our phone system and also for our link to our router out of the building that goes to the WAN.  We do not have access to that router as our ISP maintains that.

For the most part, most of the switches at a location will be linked up by the Gigabit Ethernet interfaces on this switch.  These ports are all in trunk mode.   Most of our switches are just Catalyst 2900 or Catalyst 3500 switches.  We do however also have some HP ProCurve Switches. 

What we usually do is enable IP multicast-routing on the Cisco Catalyst 3550-12G and also enable ip pim-dense mode on the VLANs that will have PCs or wireless on them.  Other then setting up the trunk port on the switches in our closets at the location and enabling the appropriate VLAN access on each port, we really don't program anything else on the switches.  

Is this generally a best practice setup for a LAN of say 200 to 300 devices?   Is there any other configuration needed?   I am getting complaints sometimes of slow access to the file server that is on the same LAN.  Usually access to the internet does not tend to be an issue.  I also get complaints sometimes that our imaging which uses multicast is slow and sometimes even will slow down the whole network.   What are some things I can do to troubleshoot this?   Also are there other settings I should be configuring?  I am sorry for all of the questions as I am a little new at networking.  I understand the basics of VLANs and IP addressing, but beyond that I realize I still have a lot more to learn.

Thanks for any help that anyone can provide.

[dominic.caron]

Hi,

About the 2900 and 3500 switch....are those XL generation switchs?

Modern multilayer switch can do IGMP-snooping to control multicast. In the case a 2900XL and 3500XL, they must rely on CGMP. I dont think your multicast router(3550) support CGMP. Without CGMP, the XL switch will process multicast packet like broadcast. The problem with that and the XL is the replication engine...its slow. You cannot replicate a flow of data on all ports at more then 10-15 Mbps for imaging type usage. The switch will start to have output error and it will affect user experience. I think it fits the problem you are having.

[krabilld1]

Yes we do have some 2900 and 3500 XL switches.   If the 3550 doesn't support CGMP then what options do I have?   I have turned on ip-multicast and ip pim-dense mode on my VLANs on the 3550.   Is that all I can do as far as configuration on the 3550?   Is there anything I should be setting on my 2900XL or 3500XL switches?   It seems like when I do imaging I end up with essentially a broadcast storm on my entire network.  

[dominic.caron]

I've check a few things and CGMP might be supported on the 3550 platform if you have IP services licences. You could try that or upgrade you equipement.