From: Hosking, Darren (dhosking@commander.com)
Date: Sat Jul 01 2006 - 09:03:28 ART
I've just tried to migrate a customer from a HP 5308 core switch to a
Cisco 3750G-48 (enhanced) and the performance of Microsoft NLB (to a
group of terminal servers) was woeful! The servers and clients are in
the same vlan so multicast routing is not being used (but is on in
preparation for segmenting the network).
The clients were still on HP edge switches and the servers were moved to
the 3750 core stack. I added static mac entries for the multicast
address pointing to the 14 server ports and performance was still bad.
Without the static mac entries the multicast traffic appears to be
flooded to all ports on the 3750.
Has anyone seen this problem? Any suggestions?
The HP has a 76Gbps backplane and the 3750 has a 32Gbps backplane but
this can't be the only factor as the performance was about 10 times
worse (eg network computer terminal login 30 seconds vs 5 minutes). The
HP also doesn't require any special configuration apart from turning
IGMP snooping on.
Does Microsoft NLB actually use IGMP? It looks the the server has a
normal (ie not class D) IP address with a multicast mac address and
responds to ARP with the muticast mac address.
I can't believe the 3750 performed so badly!?!?!
Are static MAC entries handled in software (can't be)?
Thanks, Darren
Ps the 3750 is running c3750-ipservicesk9-mz.122-25.SEE1.bin
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