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New Member

QoS for port speed

We have a 3750 switch, and a 1gigabit uplink, we want to stop devices connected to this switch saturating all the uplink, and therefore want to have some sort of policy where we can limit servers to says 600mbps and burst up to 800mbps, making sure that no server connected to the switch can use 1gbps at one time which would affect other traffic. I understand this can be completed via QoS but I don't really know where to start, can you assist? Ideally we would like to have each server to be able to burst up to 1gbps to be shared out to all the servers, so each server can burst up to 1gbps but traffic on the other servers won't suffer, but I'm not sure if there is a way to do this.

Looking forward to your replies.

4 REPLIES
Gold

QoS for port speed

This document is somewhat general, but gives you  a framework to start with.

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoS-SRND-Book.html

New Member

QoS for port speed

I was hoping that someone could provide specifics maybe even commands to assist. I have read plenty of documentation, I'm still not sure the best way to do this.

Super Bronze

Re: QoS for port speed

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Posting

On every host port, you could implement an ingress service policy which polices bandwidth to 600 Mbps.

The problem doing that is two such hosts could still saturate your gig uplink, additionally if the was excess bandwidth available it would go unused.

The 3750 does support 4 egress queues per port.  If you can identify specific traffic that is of the type that bursts up to gig, you could direct such traffic to a dedicated queue that has less of a shared bandwidth allocation than traffic that isn't so bandwidth hungry.  This would allow that other traffic better usage of available bandwidth.

New Member

Re: QoS for port speed

Ok so I have tried using srr-queue bandwidth limit which does the trick for outgoing, but not incoming.

So I tried using a rate limit option but if I am understanding this correctly the 3750 has a limit to the size of this, and to achvieve what I want (limiting a server to say 800mbps) isn't possible through this command.

Any other suggestions or am I looking at this the wrong way? Theres all sorts of traffic that is being used, and we don't want to limit based on certain types of traffic, having a method to just limit to say 800mbps seems an option, but we need this incoming and outgoing.

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