Qos on Switch and Router vs PacketShaper

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Oct 26th, 2009
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I am using a PacketShaper in my network. My bandwidth was 10Mbps and now i have updated it to 12Mbps. The problem is i dont have money to extend the licence. So I am thinking of a solution to use QoS on switches and routers for the rest of 2Mbps (few classes: maybe 2 or 3)!

My traffic flow is the following : core switch -> PIX firewall-> screen switch->screen router! The screen switches are 2950G and the screen router is 3845. I was thinking to make marking on screen switch and shaping on screen router (cause on firewalls i have VPNs ended thats why i just excluded core switches here). These devices are not doing complex things in the network, the router has only 2 BGP neighbours (no other routing protocol, only static routes). My question is, could I implement such thing? it will be a problem regarding memory for the specified devices? what are your suggestions? did somebody implemented this double solution with QoS and PacketShaper for shaping in his network? Thanks a lot!

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Joseph W. Doherty Mon, 10/26/2009 - 18:55
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Depending on our IOS on the 3845, and depending on what exactly you're trying to accomplish with QoS, you might find it will suit your requirements, with or without a Packeteer appliance.

Doubt you would need to use the QoS features of the 2950G.

Router QoS memory requirments are usually minor; also doubt you would have an issue with that.

rolandcostea Tue, 10/27/2009 - 02:11
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The shaper should be used (company policy) but now i have to mix it with QoS on router (and/or) switch.What i have to do is just allow some amount of bandwidth per business traffic for lets say 2 or 3 classes(projects) that will be in those 2 Mbps difference. The shaper is placed between screen switch an screen router. What i have to do is bypass the shaper for specific traffic. Question is? should i mark something on the switch? just before shaper...and shape traffic on router or do all on the router?

Joseph W. Doherty Tue, 10/27/2009 - 05:08
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"Question is? should i mark something on the switch? just before shaper...and shape traffic on router or do all on the router? "

Generally, and should also be true for your switch and router, router has better QoS featurs including classification and shaping. So, if possible, would try to utilize QoS features of just the router.

As to doing some kind of shaping for the extra 2 or 3 classes, it's probably possible but might not work as effectively as letting the router manage the total bandwidth allocation. This is assuming you permit classes to utilize bandwidth not being used by other classes.


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