Router LSP settings missing, initial password and Internet drop

The LDP determines the integrity of the session by detecting the LDPPDU transmitted on the session connection, LSR a live state timer for each session, refreshes the timer every time a LDPPDU is received, and if the timer times out before the new LDPPDU is received, LSR thinks the session is interrupted and the equivalence relationship fails. LSR closes the corresponding transport layer connection and terminates the session process.

Second, the establishment of LSP in the MPLS domain also to prevent the generation of loops, LDP loop detection mechanism can establish the LSP loop, and avoid the label request and other messages occur loop.

1, in the Transfer label binding message contains the hop count information, every jump that the value plus one, when the value exceeds the specified maximum value of the loop, terminate the establishment of the LSP process.

2, in the transfer label binding message to record the path information, every jump, the corresponding LSR check their ID is in this record. If not, add your own ID to the record, and if so, show a loop that terminates the establishment of the LSP process.

Third, MPLS also supports the LDP mechanism based on constraint routing, the so-called CR-LDP, that is, when the portal node initiates the establishment of LSP, it attaches some constraint information to the establishment of LSP route in the label request message, which can be the precise designation of the LSR along the route, that is, the LSR on the LSP. , this is called strict explicit routing, we can also be the choice of downstream LSR fuzzy restrictions, that is, only specify the establishment of the individual LSR on the LSP, at this time is called a loose explicit route.

Iv. LDP by way of building LSP, here we note that we should use the information in the LSR routing forwarding to determine the next hop, and the information in the routing forwarding is generally collected through routing protocols such as IGP and BGP. However, LDP is not directly associated with a variety of routing protocols, only indirectly using routing information.

V. LDP is specifically used to implement the label distribution protocol, but LDP is not the only label distribution protocol for BGP, RSVP and other existing protocols are extended, but also can support the distribution of MPLS tags, some applications of MPLS also need to extend some routing protocols.

Vi. Resource Reservation Protocol an RSVP can be extended to support the distribution of MPLS tags, while in the transfer of tag-bound messages, it can also carry information reserved by resources, in this way, the LSP can have resource reservation function, The extension of the RSVP protocol is primarily to add new objects to its path and RESV messages, which, in addition to carrying tag-binding information, can carry restrictions on the path of LSR along the route, thereby supporting the function of LSP-constrained routing.