All,
LDP discovery messages are sent as a UDP packet to the LDP port at the
group multicast address for all routers on the subnet. When ldp-tunneling is
turned on LDP treats the RSVP signaled LSPs as single hops. This allows an
LDP speaker to establish a session with the router at the far end of the
RSVP signaled LSP.
The Junos manual says that LDP control packets are routed hop-by-hop
rather than carried through the LSP. How does a UDP packet destined for a
Multicast address get routed to the LDP speaker at the end of the RSVP
signaled LSP if it's not being sent over the RSVP signaled LSP ?
Snippet from the interfaces, class of service and firewall manual (5.0):
When you configure the router to run LDP across RSVP-established LSPs, LDP
will automatically establish sessions with the router at the other end of
the LSP. LDP control packets are routed hop-by-hop, rather than carried
through the LSP. This allows you to use simplex (one-way) traffic-engineered
LSPs. Traffic in the opposite direction flows through LDP-established LSPs
that follow unicast routing rather than through traffic-engineered tunnels.
Tyler J. Wessels
Tier III IP Engineer
Level(3) Communications
This archive was generated by hypermail 2b29 : Mon Aug 05 2002 - 10:42:38 EDT