D-Link DGS-3630 User Manual 1 - Page 609

DGS-3630 Series Layer 3 Stackable Managed Switch Web UI Reference Guide Parameter Label Retention Mode Loop Detection Path Vector Limit Hop Count Limit Authentication PHP Trap Status Graceful Restart Neighbor Liveness Time Recovery Time Description Select the label retention mode here. Options to choose from are Liberal and Conservative. If the label distribution method is Downstream-Unsolicited and the label retention mode is conservative, once the LSR received label bindings from LSRs which are not its next hop for that FEC, it discards such bindings. If the label retention mode is liberal, it maintains such bindings. It helps to speed up the setup of LSP in case there is a change in the next hop. Select the Default option to use the default setting, which is Liberal. Select to enable or disable the loop detection feature here. LDP loop detection makes use of the Path Vector and Hop Count TLVs carried by the label request and label mapping messages to prevent looping of LDP messages. If enabled, LDP does not send the LDP message that violates the path vector check or hop count check to next hop. Enter the path vector limit value here. The range is from 1 to 255. If loop detection is enabled, the LDR ID that is in the path vector list of the label mapping message or the label request message or the path vector length exceeds the maximum length, then it is deemed that a loop occurs. Select the Default option to use the default value, which is 254. Enter the hop count limit here. The range is from 1 to 255. This feature is used to configure the maximum number of hops permitted in the LSP setup. Select the Default option to use the default value, which is 254. Select to enable or disable the authentication feature here. If the LDP MD5 authentication is enabled, the LSR applies the MD5 algorithm to compute the MD5 digest for the TCP segment that will be sent to the peer. This computation makes use of the peer password as well as the TCP segment. When the LSR receives a TCP segment with an MD5 digest, it validates the segment by calculating the MD5 digest (using its own record of the password) and compares the computed digest with the received digest. If the comparison fails, the segment is dropped without any response to the sender. The LSR ignores LDP Hellos from any LSR for which a password has not been configured. Select the Penultimate Hop Popping (PHP) behavior here. Options to choose from are Implicit Null and Explicit Null. If the egress router advertises the Implicit Null label, the upstream will do PHP. If the egress router advertises the Explicit Null label, the upstream will keep the outer label without popping. Select to enable or disable the LDP trap feature here. Select to enable or disable the graceful restart feature here. LDP graceful restart provides a mechanism that helps to minimize the negative effects on MPLS traffic caused by the Label Switching Router's (LSR) control plane restart. It extends the LDP to preserve the MPLS forwarding state during LDP session recovery, so that the data plane is not impacted. The graceful restart will be used by the LDP session only when both local and peer are enabled. Enter the neighbor liveness time value here. When the device detects that its LDP session with a neighbor went down, it tries to re-establish LDP communication with the neighbor in the reconnection time. The reconnection time is set according to the lesser of the FT reconnect timeout value advertised by the neighbor and the local neighbor liveness time. If the LDP session cannot be established within the reconnection time, all associated stale label forwarding entries will be deleted. If LDP graceful restart is enabled, the advertised FT reconnect timeout is set according to the neighbor liveness time value. The range is from 5 to 300 seconds. Select the Default option to use the default value. Enter the recovery time value here. If LDP graceful restart is enabled and an LDP session is re-established, the device will complete the exchange of the label mapping information with its neighbor within the recovery time. After the recovery timer expired, the device will delete all label forwarding entries that are marked stale. The range is from 12 to 600 seconds. Select the Default option to use the default value. 597