QOS and WAAS compression

Unanswered Question
Aug 26th, 2008

I have implented WAAS between sites over our WAN and I am also implementing QOS. I am looking for advice on a situation I am having with policing NetApp traffic where WAAS is implemented.

In source site "A" I have some NetApps off an LAN interface and on that LAN interface I am policing that NetApp traffic to 30Mb as destination site B that I am sending that NetApp data to is a DS-3 and I want to leave 15Mb of room for other traffic.

I have implemented WAAS off of seperate interfaces off of each router using WCCP.

The WAAS is compressing this traffic by 40-60% of the original size, with the other WAAS optimizations I am seeing anywhere from 10-20Mb of NetApp traffic hit remote sides serial interface.

I could adjust the police rate on the Source site "A" LAN interface by adding another 10Mb but in a situation where that traffic might not be optimized optimally I could saturate destination site "B" serial interface.

I thought about using EEM to script out something where the router at Site A could login to router at Site B to take bandwidth measuremetns on Site B and then adjust it's own police rate, but don't know if that is the best way or would over-complicate things.

Thanks in advance.

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ftikphillips,

Since the WAAS device will preserve the header information when optimizing traffic it is possible to configure QOS policies on intermediate devices to act on optimized traffic. So you could just configure your policers to limit the amount of NetApp traffic on the WAN and allow room for other applications. Limiting them to 30Mbps would still give you close to 45Mbps of overall throughput after compression and make things less complicated. I am assuming in this example that the NetApps are running something other than CIFS for replication (in which case you would need to match 4050 traffic instead).

Configure a policy and class match as such

class-map match-any NetApp

match access-list 101

policy-map NetApp

class-map NetApp

police cir 30000000 32000 conform-action transmit exceed-action drop

access-list 101 permit ip host host

access-list 101 deny any any

Site A

interface WAN-Interface

bandwidth 45000

max-reserve-bandwidth 95

service-policy output NetApp

Site B

interface WAN-Interface

bandwidth 45000

max-reserve-bandwidth 95

service-policy output NetApp

HTH

Mike

ftikphillips Wed, 08/27/2008 - 04:22

I already have the policy applied just as you said and it does the job I want without WAAS in place. Put WAAS in place and WAAS takes that trafic policed to 30Mb and compresses and reduces the traffic the way that WAAS does down to anywhere from 10-20Mb of traffic on the recieving end. When that recieving end can recieve another 10-20Mb of traffic depending on how much date the WAAS are reducing.

Whats the traffic rate on the sending end of WAAS? Are you policers being activated any more?

If you have a compression rate of 1.5x for this traffic as you say then if you get your outbound sending rate to 30Mbps optimized, enough to hit the policers then you should see an effective throughput of 45Mbps once the policers become active.

From what you are describing it sounds like you need to send more data with the NetApps to get the throughput rate up. Correct?

Mike

ftikphillips Wed, 08/27/2008 - 04:30

The sending end is being policed on the LAN interface of the router to 30Mb. If I increase it to 60Mb to counter when the WAAS is compressing at 50% then on the recieving end I get close to 30Mb recieved. Problem is WAAS compression and data reduction isn't alwasys going to be at 50%. Compression and Data reduction are dynamic so when it doesn't reduce that much data, since my sending end is policing to 60Mb I could saturate the recieving end's pipe of 45Mb

Why don't you police on the WAN interfaces after optimization? That way you don't have to deal with the before compression dynamics. You can set a static rate and if exceeded it gets dropped and you still get the protection you are looking for. Doing it on the LAN interface you are correct, will give you mixed results based on the level of optimization for the traffic. Doing it between the WAEs is a much better practice IMHO.

Why don't you police on the WAN interfaces after optimization? That way you don't have to deal with the before compression dynamics. You can set a static rate and if exceeded it gets dropped and you still get the protection you are looking for. Doing it on the LAN interface you are correct, will give you mixed results based on the level of optimization for the traffic. Doing it between the WAEs is a much better practice IMHO.

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