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Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
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Chapter 3 QoS in an AVVID-Enabled Campus Network
Server Farm Switch Selection
class-map: VOICE (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
match: access-group name VOICE
class-map: class-default (match-any)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
match: any
0 packets, 0 bytes
5 minute rate 0 bps
Voice over IP Call Control
The current release of Cisco CallManager includes the ability to configure the CoS and ToS values for
all VoIP control and management traffic from CallManager, the IP phones, H.323, Skinny Protocol, and
MGCP gateways. With this user-configurable classification, network element access lists are no longer
required to mark VoIP control traffic. However, some network managers may choose to enforce policy
at the edge of their network and not trust the markings that end devices provide. The following
configuration example uses a Catalyst 6500 with Multilayer Switch Feature Card 2 (MSFC2) and Policy
Feature Card (PFC2) and Catalyst Operating System (Catalyst OS). In this example, the switch
recognizes and classifies VoIP control traffic upon ingress to the network.
Skinny Protocol
Cisco CallManager communicates with IP phones and gateways using TCP ports 2000-2002. The
example below marks all Skinny Protocol traffic from IP phones and gateways (VLAN 110) and Cisco
CallManager (4/2) with a DSCP of AF31, which is backwardly compatible with IP Precedence 3.
Step 1
Enable switch-wide QoS.
cat6k-access> (enable) set qos enable
Step 2
Create an ACL (ACL_IP-PHONES) to mark all Skinny Client and Gateway Protocol traffic from the IP
phones and from Skinny Protocol gateways with a DSCP value of AF31 (decimal of 26).
cat6k-access> (enable) set qos acl ip ACL_IP-PHONES dscp 26 tcp any any range 2000 2002
Step 3
Add an entry to the ACL_IP-PHONE access list to trust all DSCP markings from the IP phone so that
the RTP traffic with ToS of is not rewritten.
cat6k-access> (enable) set qos acl ip ACL_IP-PHONES trust-cos ip any any
Step 4
Create an ACL (ACL_VOIP_CONTROL) to mark all Skinny Client and Gateway Protocol traffic from
Cisco CallManager with a DSCP value of AF31.
cat6k-access> (enable) set qos acl ip ACL_VOIP_CONTROL dscp 26 tcp any any range 2000 2002
Step 5
Accept incoming Layer 2 CoS classification.
cat6k-access> (enable) set port qos 5/1-48 trust trust-cos
Step 6
Inform the port that all QoS associated with the port will be done on a VLAN basis to simplify the
configuration.
cat6k-access> (enable) set port qos 5/1-48 vlan-based