Configuring GRE tunnel parameters 185Configuring checksum for GRE tunnelsEnable end-to-end checksums to force the router to drop any corruptedpackets. You can only configure checksum on GRE tunnels.By default, checksums are disabled.Procedure stepsStep Action1 To enter configuration mode, enter:configure terminal2 To specify the name of the tunnel to configure, enter:interface tunnel 3 To enable or disable checksum for tunnel packets, enter:[no] tunnel checksum—End—Configuring tunnel key for GRE tunnelsConfigure an ID key for a tunnel interface. This key must be set to thesame value on the tunnel endpoints. The key field is used for identifying anindividual traffic flow within a tunnel. Tunnel ID keys can be used as a formof weak security to prevent misconfiguration or injection of packets from aforeign source. However this is not a reliable security option.You can only configure tunnel key on GRE tunnels. By default, no key isconfigured.Procedure stepsStep Action1 To enter configuration mode, enter:configure terminal2 To specify the name of the tunnel to configure, enter:interface tunnel 3 To configure tunnel key, enter:[no] tunnel key <0-4294967295>—End—Nortel Secure Router 4134Security — Configuration and ManagementNN47263-600 01.02 Standard10.0 3 August 2007Copyright © 2007, Nortel Networks.
