Avaya Configuring Dial Services Bedienungsanleitung PDF herunterladen (Seite 151)

Dial-on-Demand Implementation Notes

117353-B Rev. 00

6-17

Exceptions for Sending Routing Updates

Routing updates are sent independent of data transmission when:

• An IP or IPX interface becomes active for the first time.

When an IP or IPX interface first initializes, it sends routing updates to every

node in the network. If there is no data to send, the connection expires in the

time you specify in the Minimum Duration Time parameter.

• The RIP Broadcast Timer (IP) or RIP/SAP Update Interval (IPX) expires.

Each time the broadcast timer or update interval expires, the protocol can

request to send updates over an active connection. If you enable dial

optimized routing, the value of the timer defaults to a high value so that

connections are infrequent. Reducing the value of the broadcast timer or

update interval defeats the purpose of dial optimized routing.

If a connection is made because there is data to send, the router uses this

opportunity to send routing updates. Consequently, these timers reset instead

of expiring. This further reduces the frequency of connections made by a

protocol request.

Maintaining the Routing Table

Although dial optimized routing limits the amount of routing information sent

across the network, you can maintain the accuracy of the routing tables using the

following methods:

• Set the Hold Down Timer parameter to a higher value than the Broadcast

Timer or Update Interval parameter.

The Hold Down Timer parameter specifies how long unusable routes are

advertised after the route is invalid. This ensures that unreachable routes

remain in the routing table long enough to be broadcast over an active

connection.

• Synchronize protocol requests for a connection.

When a connection is active, the router sends status messages to IP or IPX,

alerting the protocol that it can send routing updates. If IP or IPX does not

receive this connection message, it makes a separate request for a connection.

This request resets the Minimum Duration Time parameter and the connection

then remains active for the specified time.

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Avaya Configuring Dial Services Bedienungsanleitung Seite 151