You can do a search on cisco.com (or google) for LLQ QOS.
Here's a sample voice qos config:
class-map match-any voice-control
match ip dscp af31
match ip dscp cs3
match access-group 101
class-map match-any voice-RTP
match ip dscp ef
match ip rtp 16384 16383
!
!
policy-map Voice-QoS
class voice-RTP
priority [bandwidth-value]
set dscp ef
class voice-control
bandwidth [bandwidth-value]
set dscp af31
class class-default
fair-queue
!For MGCP
access-list 101 permit udp any any range 2427 2428
!For H.323
access-list 101 permit tcp any any range 1718 1720
access-list 101 permit tcp any any eq 1731
!For Skinny (phones registered to CCM)
access-list 101 permit tcp any any eq 2000
!For Sip
access-list 101 permit tcp any any eq 5060
interface x/x
service-policy output Voice-QoS
Note that for some versions of IOS, the command 'match ip dscp' needs to be replaced with 'match dscp'.
What this will do is take any traffic marked as a DSCP of 'ef', or any unmarked RTP traffic, and marks it as RTP traffic and sets the DSCP values accordingly. This traffic is sent to a priority queue. Then, it takes any traffic marked as DSCP of 'af31' or running on port thatis used for control traffic, marks it as control traffic (and sets the DSCP if needed), then puts it in a queue. All other traffic is sent to the fair-queue.
Estimate about 8K of call-control traffic per call. You can find out how much bandwidth you will need for RTP traffic with the voice-call bandwidth calculator found here:
http://tools.cisco.com/Support/VBC/do/CodecCalc1.do
Just be careful when you apply this QoS policy that those 100 and 101 access-lists aren't overwriting any ACLs that you already have configured.
For DSP resources, you will want the DSP calculator:
http://www.cisco.com/cgi-bin/Support/DSP/cisco_prodsel.pl
hth,
nick
