Re: [mpls-linux-general] reg LDP

[James R. L. <jl...@mi...>]

I can give you a quick overview of mesg odering, but you will want to
look at RFC3036 for the details.

I'm only going to explain the direct/DU/Independent/Conservitive mode
of operation (look to the RFC as to what those mean)

-Each LDP speaker is configured to talk LDP on specific interfaces.
-Each LDP speaker sends udp hello's on their interface to the all routers
 multicast address, port 646.
-When an LDP speaker recieves a hellos it creates a logical adj for it.
-For each adj the LDP speaker decides whether it will play the
 active role or the passive role in the adj. (only 2 LDP speakers per adj,
 on a broadcast medium an LDP speaker will form multiple adj).  The
 process of deciding active vs passive is outlined in the RFC.
-The active LDP speaker in the adj will attempt to create a TCP connection
 to the passive LDP speaker on port 646.
-Once a TCP connection is established each LDP speaker sends an Init
 message.
-When an LDP speaker recieves a Init message it looks at the parameters
 in the Init message and compares them with it configured parameters.
 If the parameters are acceptable a keepalive message is sent back.
 If the parameters are un-acceptable a notification is sent back and the
 TCP connection is closed
-When an LDP speaker hears the first keepalive for an adj, it then sends out
 one or multiple address messages which advertise the IP address attached
 to the LDP speaker.
-After sending address messages, the LDP speaker sends label advertisements
 for each FEC in it routing table.
-When a route changes, label withdraws and mappings are issued.
-When an interface changes, address withdraw and address messages are issued.

I hope this atleast gives you a starting point.  The RFC is really the
best place to get the details though. (ofcourse you can alwyas read the
source to ldp-portable as well :-)

Jim

On Tue, Mar 19, 2002 at 11:20:34AM -0800, Anil H wrote:
> hi,
> 
> Could ne1 give me the basic flow for LDP (for eg the
> sequence of messages) r some pointers to were i can
> find the information apart from the RFC.
> 
> Thanks in advance,
> Anil
> 
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-- 
James R. Leu