WAAS QoS question

Unanswered Question
Nov 12th, 2007

Hi all

I have a question regarding QoS and WAAS. From documentation I've ascertained that QoS needs to be done on the routers.

Configuring a service policy on the output interface can be used to guarantee bandwidth for certain applications. However, the amount guaranteed would be applied to the compressed output from the WAE.

Is there a way to guarantee bandwidth for the uncompressed amount of traffic? For example, I want to guarantee 256KBps for SQL - the reduction achieved on the WAE will be variable, and I want to be able to guarantee the bandwidth for the unoptimized traffic.

Is there a strategy for achieving the above?

Thanks for any assistance.

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Zach Seils Tue, 11/13/2007 - 23:54

Anthony,

One option is to apply a service-policy outbound on the interface facing your WAEs. Your service-policy criteria would need to take traffic direction into consideration, since traffic going towards the WAEs can ultimately be destined for the LAN or the WAN (you want towards the WAN).

Zach

osiristrading123 Wed, 11/14/2007 - 23:33

Hi Zach

Thanks for the reply. If we apply a service policy to the interface facing the WAE (for WAN traffic), won't we have to choose an arbitrary amount to which to shape the traffic, since the LAN interface will have much higher bandwidth than the WAN? If there is no queueing taking place, QoS will not function. However, the problem is that the data reduction is variable, making choosing the shape value difficult.

Zach Seils Thu, 11/15/2007 - 00:09

Your points are well taken. Let me think on this a bit and come back to you.

Thanks,

Zach

osiristrading123 Thu, 11/15/2007 - 02:51

Would marking the packets up to a certain bit rate with a high precendence (on the LAN side), and then the rest as a lower precedence work?

From what I've heard, WAAS will preserve ToS/DSCP. But is this per packet, per flow or per a connection? If it's per packet, WFQ may take care of the priority on the WAN interface on the router.

But this approach could cause a lot of out-of-order packets and be counter productive overall.

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