MPLS LDP messages (discovery, session, advertisement, and notification messages) are exchanged between LDP peers through two channels:
- LDP discovery messages are transmitted as User Datagram Protocol (UDP) packets to the well-known LDP port.
- Session, advertisement, and notification messages are exchanged through a TCP connection established between two LDP peers.
The MPLS LDP—Lossless MD5 Session Authentication feature allows an LDP session to be password-protected without tearing down and reestablishing the LDP session.
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Old Style |
New Style |
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R2(config)#mpls ldp neighbor 1.1.1.1 password 123 |
R2(config)#access-list 99 permit 1.1.1.1 |
The disadvantage of using the old method is that when new password is required for a session, this change would require the LDP session to be tear down. With this feature New passwords can be implemented/changed without having to tear down the existing LDP session
