Cisco IOS Wide-Area Networking Configuration Guide - Free Books

configured with the L2TPv3 Control Message Hashing feature. Authentication passwords configuredwith the older, CHAP-like authentication system cannot be updated without tearing downL2TPv3 tunnels.The L2TPv3 Digest Secret Graceful Switchover feature allows two control channel passwords to beconfigured simultaneously, so a new control channel password can be enabled without first removing theold password. Established tunnels are rapidly updated with the new password, but continues to use theold password until it is removed from the configuration. This allows authentication to continue normallywith peer PE routers that have not yet been updated to use the new password. After all peer PE routersare configured with the new password, the old password can be removed from the configuration.Manual Clearing of L2TPv3 TunnelsCisco IOS Release 12.0(30)S introduces the ability to clear L2TPv3 tunnels manually. In Cisco IOSreleases earlier than Release 12.0(30)S, no provision was made to manually clear a specific L2TPv3tunnel at will. This functionality provides users more control over an L2TPv3 network.L2TPv3 Tunnel ManagementNew and enhanced commands have been introduced to facilitate managing xconnect configurations anddiagnosing problems with xconnect configurations. No specific configuration tasks are associated withthese commands.For information about these Cisco IOS commands, go to the Command Lookup Tool athttp://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List, All Releases.New and enhanced commands were introduced in the following releases:• Syslog, SNMP Trap, and show Command Enhancements for L2TPv3 in Cisco IOSRelease 12.0(31)S, Cisco IOS Release 12.2(27)SBC.• Control Message Statistics and Conditional Debugging Command Enhancements37