Cisco Cisco Expressway 维护手册
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Off: the Expressway always handles the call signaling.
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The call consumes either an RMS Call license or a Registered Call license on the Expressway.
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On: the Expressway handles the call signaling when the call is one of:
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a traversal call
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an H.323 call that has been modified by Call Policy or FindMe such that:
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the call resolves to more than one alias
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the source alias of the call has been modified to display the associated FindMe ID
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the FindMe has a "no answer" or "busy" device configured
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one of the endpoints in the call is locally registered
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a SIP call where the incoming transport protocol (UDP, TCP, TLS) is different from the outgoing protocol
In all other cases the Expressway removes itself from the call signaling path after the call has been set up.
The Expressway does not consume a call license for any such calls, and the call signaling path is simplified.
This setting is useful in a
The Expressway does not consume a call license for any such calls, and the call signaling path is simplified.
This setting is useful in a
, when used on the directory Expressway. In such
deployments the directory Expressway is used to look up and locate endpoints and it does not have any
endpoints registered directly to it.
endpoints registered directly to it.
Call Loop Detection Mode
Your dial plan or that of networks to which you are neighbored may be configured in such a way that there are
potential signaling loops. An example of this is a
potential signaling loops. An example of this is a
, where all systems are neighbored together in a
are set too high, a single search request may be sent repeatedly
around the network until the hop count reaches 0, consuming resources unnecessarily.
The Expressway can be configured to detect search loops within your network and terminate such searches through
the Call loop detection mode setting, thus saving network resources. The options for this setting are:
the Call loop detection mode setting, thus saving network resources. The options for this setting are:
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On: the Expressway will fail any branch of a search that contains a loop, recording it as a level 2 "loop
detected" event. Two searches are considered to be a loop if they meet all of the following criteria:
detected" event. Two searches are considered to be a loop if they meet all of the following criteria:
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have same call tag
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are for the same destination alias
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use the same protocol
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originate from the same zone
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Off: the Expressway will not detect and fail search loops. You are recommended to use this setting only in
advanced deployments.
advanced deployments.
Identifying Calls
Each call that passes through the Expressway is assigned a Call ID and a Call Serial Number. Calls also have a Call
Tag assigned if one does not already exist.
Tag assigned if one does not already exist.
Call ID
The Expressway assigns each call currently in progress a different Call ID. The Call ID numbers start at 1 and go up to
the maximum number of calls allowed on that system.
the maximum number of calls allowed on that system.
Each time a call is made, the Expressway will assign that call the lowest available Call ID number. For example, if
there is already a call in progress with a Call ID of 1, the next call will be assigned a Call ID of 2. If Call 1 is then
disconnected, the third call to be made will be assigned a Call ID of 1.
there is already a call in progress with a Call ID of 1, the next call will be assigned a Call ID of 2. If Call 1 is then
disconnected, the third call to be made will be assigned a Call ID of 1.
The Call ID is not therefore a unique identifier: while no two calls in progress at the same time will have the same Call
ID, the same Call ID will be assigned to more than one call over time.
ID, the same Call ID will be assigned to more than one call over time.
Note that the Expressway web interface does not show the Call ID.
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Cisco Expressway Administrator Guide
Dial Plan and Call Processing