QoS - Match-all vs match-any

It seems like most of the QoS configuration examples I see use match-all.... Like I have seen VoIP QoS configs where there will be a match-all, then the match elements will be for multiple DSCP's...

ie:
class-map match-all VOIP
match dscp ef
match dscp af31

Now, wouldn't that be impossible? Since you can't have multiple DSCP's on a single packet?

I just set up a new QoS template with:
class-map match-any VOIP
match dscp ef
match dscp af31

Maybe I've just been reading bad info? Can someone clarify?

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Comments

Forsaken_GA

If you see anything blatant like that, it probably means that the author and their editor weren't paying attention. match-all is the default, so it's an easy thing to overlook

networker050184

You are correct. A match all needs to match all and a packet will only have one DSCP marking. You will need a match any like your example. What source are you getting the bad info from?

keenon

mzinz wrote: »

It seems like most of the QoS configuration examples I see use match-all.... Like I have seen VoIP QoS configs where there will be a match-all, then the match elements will be for multiple DSCP's...

ie:
class-map match-all VOIP
match dscp ef
match dscp af31

Now, wouldn't that be impossible? Since you can't have multiple DSCP's on a single packet?

I just set up a new QoS template with:
class-map match-any VOIP
match dscp ef
match dscp af31

Maybe I've just been reading bad info? Can someone clarify?

bad info. match-all as a given (dscp example posted excluded) requires that all conditions are met. Basically it acts as a "and" operation. Where match-any does a "or" operation.

mzinz

Thanks for all the replies guys, totally makes sense.

One last question:
In most configuration examples, RTP and Control traffic is separated for VoIP QOS. What's the benefit to doing this? Why not bundle them into a single class-map?

It just seems like since control takes so little bandwidth but can be equally important to voice traffic it would make sense to combine them into a single queue...

networker050184

The control traffic is not as delay sensitive so it does not need to be in the expedited queue. I've seen implementations where they are both put in the same queue, but its not necessary. If the message to end the call doesn't get there with little delay its not as big of a deal as if your actual voice traffic was delayed.

ColbyG

I rarely, if ever, use match-all. Sometimes I forget to type the match-any at the end though.:p

mzinz

Thanks for the replies guys