Cisco Cisco Expressway Maintenance Manual
Configuring Hop Counts
Each search request is assigned a hop count value by the system that initiates the search. Every time the request is
forwarded to another neighbor gatekeeper or proxy, the hop count value is decreased by a value of 1. When the hop
count reaches 0, the request will not be forwarded on any further and the search will fail.
forwarded to another neighbor gatekeeper or proxy, the hop count value is decreased by a value of 1. When the hop
count reaches 0, the request will not be forwarded on any further and the search will fail.
For search requests initiated by the local Expressway, the hop count assigned to the request is configurable on a
zone-by-zone basis. The zone’s hop count applies to all search requests originating from the local Expressway that
are sent to that zone.
zone-by-zone basis. The zone’s hop count applies to all search requests originating from the local Expressway that
are sent to that zone.
Search requests received from another zone will already have a hop count assigned. When the request is
subsequently forwarded on to a neighbor zone, the lower of the two values (the original hop count or the hop count
configured for that zone) is used.
subsequently forwarded on to a neighbor zone, the lower of the two values (the original hop count or the hop count
configured for that zone) is used.
For H.323, the hop count only applies to search requests. For SIP, the hop count applies to all requests sent to a zone
(affecting the Max-Forwards field in the request).
(affecting the Max-Forwards field in the request).
The hop count value can be between 1 and 255. The default is 15.
Note:
if your hop counts are set higher than necessary, you may risk introducing loops into your network. In these
situations a search request will be sent around the network until the hop count reaches 0, consuming resources
unnecessarily. This can be prevented by setting the
unnecessarily. This can be prevented by setting the
to On.
When dialing by URI or ENUM, the hop count used is that for the associated DNS or ENUM zone via which the
destination endpoint (or intermediary SIP proxy or gatekeeper) was found.
destination endpoint (or intermediary SIP proxy or gatekeeper) was found.
Configuring hop counts for a zone
Hop counts are configured on a zone basis. To configure the hop count for a zone:
1.
Go to the Zones page (Configuration > Zones > Zones).
2.
Click on the name of the zone you want to configure. You are taken to the Edit zone page.
3.
In the Configuration section, in the Hop count field, enter the hop count value you want to use for this zone.
Configuring Dial Plan Settings
The Dial plan configuration page (Configuration > Dial plan > Configuration) is used to configure how the
Expressway routes calls in specific call scenarios.
Expressway routes calls in specific call scenarios.
The configurable options are:
167
Cisco Expressway Administrator Guide
Dial Plan and Call Processing