h323 qos

[bigmac13]

i've got multiple h323 codecs that are connected through multiple serial interfaces (no more than 1 codec per interface). all of these codecs come through one gateway behind our main router. the way quality of service is implemented now, there is only one policy-map. this is then used on each of the serial interfaces that need it.

should i instead have a separate policy for each interface? if their are multiple sessions at the same time, will they have to split the bandwidth that the one policy grants, or will they each be given the full amount? thanks for any help...

 

[mtashiro]

You can use the same policy-map for all interfaces depending on a few things.

Are all the links the same speed?

I am assuming you are using LLQ for QoS. If you are and you use the percent command you shouldn't have any problem using the same policy. If you use a "hard" (ie specify the bandwith to reserve) number and the links are different speeds you will have issues.

If you give more details I can give better answers.

 

[tbilan]

When applying the same policy on different interfaces the policy is a separate instance for that interface. i.e. If make a policy specifying 80k of priority bandwidth for IP Prec 5 packets and then apply that policy to 3 interfaces its the same as making 3 different policies and applying different policies to each interface. The 80k is not shared between all 3 interfaces.

I don't completely understand your layout. Really the only thing you want to watch out for when using LLQ is oversubscribing your priority queue. If you have 120k of possible traffic going through a priority queue of 100k then you will still get drops when the line is busy.

Also, if you use lower speed links (< 512k) that have data packets going across them then look into link fragmentation. You don't want a huge 1500 byte packet to hold up your little voice packets.
Tom Bilan
TJBA, Inc.
CCNP, CCDP, MCSE & CNE

 

[bigmac13]

here's the QOS policy that's on there now... we've got around 12 serial connections (of equal bandwidth) and want to apply it to 5 of them (i think).

policy-map QOSout
class polycom
priority 450
class class-default
fair-queue
random-detect

 

[tbilan]

Assuming your polycom class works correctly you should be able to apply this on all the interfaces you want.

Use the show policy-map interface x/y command to see the effects of your policy.
Tom Bilan
TJBA, Inc.
CCNP, CCDP, MCSE & CNE