CCIE Voice Study

Locations dictate the maximum amount of bandwidth available for simultaneous calls originating from or destinated from a site. Locations, along with Regions, are the building blocks of Call Admission Control in CallManager.

• Locations; i.e. maximum bandwidth: applied to the Device (Phone, Gateway, etc.)
• Regions; i.e. codec selection: applied to the Device Pool

The relationship between Locations and Regions is important to understand because, when the bandwidth for a Location is exhausted, no further calls can be made (without AAR, of course). Additional calls receive a reorder tone and a message, "Not Enough Bandwidth" (see in the screen-shots below)

As a general principle:

• Always assign a location based on the network topology
• Choose ...

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Configuring QoS between CUE and CME requires identification and re-marking of packets that match the following criteria:

• Payload: RTP (i.e. UDP > 16384)
• Signaling: SIP (TCP 5060)

CUE actually already marks RTP traffic as DSCP EF, and signaling (SIP) as DSCP AF31, however best practice dictates that we will make traffic on the service policy ingress. In fact, look at the access-list counters iterate when applied to the service-engine interface (this is before any QoS marking is applied - we simply apply an ACL to verify traffic characteristics):

CME#sh ip access-lists 115
Extended IP access list 115
10 permit ip host 192.168.255.98 any dscp af31 log (8 matches)
20 permit ip host 192.168.255.98 any ...

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