Chapter 10 - WAN Link Protocols | 163 |
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>Polling Frequency
The router is required to periodically poll the Frame Relay switch at the other end of the communications link in order to determine whether the link is active. This field determines how often the router polls the switch, using the Maintenance Protocol you have selected.
If any three out of four polls go unanswered by the switch, the router will assume the Frame Relay link is down. Every sixth poll, the router requests a full status packet from the switch in order to update its table of active perma- nent virtual circuits (PVCs).
This value is in seconds. The allowable range for the value is 5 to 30. The default is 10.
Home DLCI
When Static maintenance is used on a WAN broadcast medium, this edit box can be filled in to provide a statically assigned DLCI (Data Link Control Iden- tifier) number for this interface.
This number can be configured into other routers’ DLCI Mapping Dialog Boxes so that they can communicate with this router. In order to reject packets that were sent out its own interface, this router will ignore any packets with a sending DLCI number that matches this number.
MTU
This is the Maximum Transmission Unit in bytes for the interface. This setting may need to be adjusted in order to communicate with switches or routers from other vendors which do not support full size frame packets. The allowable range for the value is 262 to 1700. The default for this value is 1500.
ϖ Note: Adjusting the MTU to a smaller size will cause fragmentation of Frame Relay packets, which will impact performance. This setting should be left at the default unless it must be changed for compatibility reasons.
