QoS on Firewall Quesiton ???

Unanswered Question
Mar 12th, 2008


I have read on a previous thread about QoS on the firewall an read the link provided.

I have one question regarding QoS on firewall

I have read that the QoS supports Priority traffic and Policed (rate limiting) traffic.

For example:

i have a 256K FR.

I can set it up that voice traffic gets priority..(i understand that)

i can also set it up that browing the net is rate limited to 128K.

so...if no voice traffic is being transmitted at all, the internet browing will still be rate limited to the 128K, or will it use the 256K available and if other traffic is present (such as voice or any other type of traffic) it will then be rate limited to 128K (ok. if voice is present i understand that it will be prioritized, and the remainder will be used for browsing)

Can someone shed some light on this as its not very clear in the cisco manual ??



Edit: I have seen an old configuration i did for the 3745 router.

i specify my class for VOIP:

class-map match-any VOIP-CLASS

match access-group 101



policy-map VOIP-POLICY


priority 300

class class-default


in my policy map, i use the "priority 300" keyword which i believe that it will prioritize the voip traffic as matched inaccess list 101, but only up to 300K ..Right ??

so the way to only allocate bandwidth when needed is by PRIORITY, and RATE LIMITING just limits the traffic no matter what else goes on ???

Thanks again.

I have this problem too.
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Jon Marshall Thu, 03/13/2008 - 01:43

Hi George

Rate limiting does exactly what it says so if you allocate 128k to browsing that is the maximum it can get, doesn't matter whether the other 128k is being used or not.


g-serghiou Thu, 03/13/2008 - 23:11



im clear now... if i want ot use all my bndwidth for browsing and allocate some fora specific service (port) then i can configure it as priority traffic..

Can i allocate a bandwidth with the priority command on the PIX, as i could do with the 3745 router?

my PIX is 515 ver 7.2(2)




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