1332 CHAPTER 76: MPLS B ASICS CONFIGURATIONFollow these steps to configure LDP MD5 authentication:Enabling MTU Signaling For correct path MTU detection, an IP router needs to know the MTU of eachconnected link.LDP can automatically calculate the minimum MTU of all interfaces on an LSP. Atingress, MPLS uses the calculated minimum MTU to determine the size of theMPLS forwarding packets, preventing a packet of a bigger size from beingdropped by a transit LSR.Follow these steps to enable MTU signaling:n Enabling/disabling MTU signaling will cause existing sessions to be reestablishedand all LSPs of the sessions to be reestablished accordingly.Configuring LDPInstancesLDP instances are for MPLS L3VPNs. You must configure LDP capability for them.Except for the command for the LDP GR feature, all commands available in MPLSLDP view can be configured in MPLS LDP VPN instance view.ConfigurationPrerequisitesBefore configuring LDP instances, be sure to complete these tasks:■ Configuring VPN instances■ Configuring MPLS basic capability■ Configuring MPLS LDP capabilityConfiguration Procedure Usually, the default value of the LDP LSR ID, that of the MPLS LSR ID, answers therequirement. In some networking schemes where VPN instances are deployed,such as MPLS L3VPN networking schemes, if VPN address spaces and the publicnetwork address space overlap, you must configure an LDP LSR ID that is differentfrom the MPLS LSR ID for TCP connections to be established normally.Follow these steps to configure LDP instances:To do... Use the command... RemarksEnter system view system-view -Enable LDP capability andenter MPLS LDP viewmpls ldp RequiredConfigure LDP MD5authenticationmd5-password { cipher |plain } peer-lsr-id passwordRequiredDisabled by defaultTo do... Use the command... RemarksEnter system view system-view -Enable LDP capability and enterMPLS LDP viewmpls ldp RequiredEnable MTU signaling mtu-signalling OptionalEnabled by default
