ccna question answer

ccna question answer

The LDP neighbor establishment first sends the HELLO packet (the HELLO packet uses UDP , the source port is 646 ). The LDP ID is 6 bytes ( 4 bytes of IP plus 2 bytes of LABEL SpaceID ) The OSPF adjacency relationship will not be established until the LDP session is successfully established or the "synchronization hold time" expires . The synchronization here indicates that the local label bundle has been sent to the LDP peer through the LDP session . However, if A is activated on the router and MPLS LDP-IGP is synchronized, and there is only one link between A and B , and no other available path to B , the OSPF adjacency will never be established. Because OSPF waits for the LDP session is established,ccna question answer, but the LDP session can not be set up because A can not learn in its routing table B of LDP routerID route, so enter an infinite loop, OSPF and LDP adjacencies will never Unable to create. In this case, LDP-IGP synchronization will activate the OSPF adjacency unconditionally , so that the link will advertise the largest.The metric value until the synchronization is complete.