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multicast drops with NIC team on BL460c G5


multicast drops with NIC team on BL460c G5

Hi there,

I have an odd problem -- whenever I have my NIC's teamed on a BL460c G5 w/Windows 2008 R2 and PSP 8.30, I see terrible multicast data at the server. I have confirmed that the data is fine up until it reaches the server, but once it hits the server I start to see a lot of packet drops, which evidence themselves as missing multicast data. This only seems to be a problem when I have the NIC's teamed. If I unteam the NIC's the multicast data is great.

I've tried using NIC teams as Automatic, Fault tolerance, faul-tolerance with preference order.

Any ideas what could be wrong?

Thanks in advance,

Honored Contributor

Re: multicast drops with NIC team on BL460c G5

Maybe it's an IGMP issue...

do you have IGMP Snooping enabled on the switches that the BL460c NICs connect? If you "show ip igmp groups" on the switch do you see the BL460c switch ports as members for the Multicast stream? Does it intermittently come and go? There could be an issue with what port the IGMP join comes out (the active NIC at the time) and where the IGMP queries are coming in and how the team responds.

If you don't have IGMP Snooping enabled, then the multicast should be getting flooded on the VLAN. Do you have other Multicast streams running and at what rate? Maybe there is a resource issue... go to NCU and look at the statistics for each NIC and make sure you aren't losing frames via receive overruns, etc.

Re: multicast drops with NIC team on BL460c G5

Thanks for the response. IGMP snooping is enable and the switch is sending the data out the switch port to the server. I verified this using SPAN ports on the server facing interfaces.

And, when the NIC's are not teamed the multicast data is great.

Does anyone know of any network related changes between Server 2008 and 2008 R2?

Zeljko Muza
Occasional Advisor

Re: multicast drops with NIC team on BL460c G5

HI, I have same problem on BL460c G5 but on BL460c G6 all work fine with 2008 R2. Do we ned to configure something in Network Utility?



Re: multicast drops with NIC team on BL460c G5


After a lot of testing I found that the problem was related to a combination of factors:

1. Number of multicast streams
2. Bandwidth of the streams
3. Number and speed of CPU's, and CPU affinity of multicast reading processes.

Basically, I found that on any given box you have to find the limit for multicast processing. It might be one stream with high bandwidth, or 10 streams of medium bandwidth, etc. The difference in processor technology between the G5's and G6's also makes a significant difference. In our particular environment, we found that the G6's are at least 50% faster in certain processes than the G5's.

So you'll have to look at your environment and just test until you find the limits for your hardware.

Good luck!