Avaya G860, Установка и эксплуатация

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Issue 1 October 2007 121
12. Configuring & Operating the Media Gateway
INVITE message, the same INVITE message is immediately sent to the second Proxy.
You can tune the number of retransmits before Hot Swap is activated.
Refer to the parameters, Proxy Hot Swap and Proxy Hot Swap Retx .
12.12.3 Working with DNS Service Record (SRV)
In order to discover Proxy servers, the Avaya G860 Media Gateway can use the DNS
Service Record (SRV) queries.
If the Proxy IP address parameter contains a domain name without a port definition
(e.g., ProxyIP = domain.com), an SRV query is performed. The SRV query returns up
to four Proxy host names and their weights. The Avaya G860 Media Gateway then
performs DNS A-record queries for each Proxy host name (according to the received
weights) to locate up to four Proxy IP addresses. Therefore, if the first SRV query
returns two domain names, and the A-record queries return 2 IP addresses each, no
more searches are performed.
If the Proxy IP address parameter contains a domain name with port definition (e.g.,
ProxyIP = domain.com:5080), the Avaya G860 Media Gateway performs a regular
DNS A-record query.
When enabled, SRV queries are used to discover Proxy servers even if the
parameter,
EnableSRVQuery is disabled.
Refer to the parameters, EnableProxySRVQuery and EnableSRVQuery .
12.12.4 Using the Proxy for Message Routing
The Avaya G860 Media Gateway can route the SIP messages directly to the
destination addresses according to the standard SIP routing rules, or permanently to
send all messages to the Proxy. In this case, all SIP messages and responses are
sent to the Proxy server.
When the Proxy is not used for the message routing, the Avaya G860 Media Gateway
allows sending INVITE messages, generated as a result of Transfer or Redirect,
directly to the URI according to the Refer-To header in the REFER message or
Contact header in 30x response.
Alternatively, it can be configured to send all the INVITE messages, including those
generated as a result of Transfer or Redirect to Proxy.
Refer to the parameters, Always Send To Proxy and Enable Proxy .
12.12.5 Using Proxy for Call Routing
Basically, call routing is performed by the Media Gateway or by SIP Proxy(s). The
Avaya G860 Media Gateway allows a number of call routing modes. You can choose
to use the internal Tel to IP routing table or always use the Proxy.
For using the internal Tel to IP routing table, the Avaya G860 Media Gateway checks
the destination IP Address in the Telephony to IP routing table for a match with
outgoing call. The proxy is used only when the destination IP addtress is not listed in
the routing table.
When using a Proxy server, you do not need to configure the Telephone to IP Routing
Table. However, if you want to use fallback routing when communication with Proxy is
lost, or to use the Calls Filtering to IP and IP Security features, or to obtain different
SIP URI host names (per called number), you need to configure the IP Routing Table.
Refer to the parameter, Prefer Routing Table .