Question on RSPAN vlan saturation

Unanswered Question
Mar 20th, 2009

I am in the process of creating a RSPAN vlan that I am going to put several servers and a full time packet Sniffer into ( Infinistream ), this is my first time using a RSPAN vlan and I am curious what side effects the switch will experience if I over subscribe the links going back to the Sniffer? Right now I am looking at about 100 servers that aren't too chatty going to 4 gig Ethernet links in one etherchannel back to the Sniffer.

At this point I am not to concerned if I saturate those links and drop packets. What I am concerned about is if it will start to beat up the switches CPU, memory, or general ability to route/switch packets. The switch in question is a 6509 w/vss 12.2(33)sxh. I'm pretty sure we will just drop packets but I wanted to be sure. If we do drop packets that's ok, the Sniffer can be scaled to include more ports to compensate as time goes on.

thanks

e-

I have this problem too.
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Giuseppe Larosa Fri, 03/20/2009 - 07:18

Hello Eric,

we had bad experience even with local span oversubscription with 12.2.(18)SXF14 with cpu going very high and losting forwarding/routing capacity.

In our case we had almost 3 Gbps of internet traffic pushed towards a 1GE destination port.

Hope to help

Giuseppe

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