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3.5.5. Address Message

An LSR sends the Address message to an LDP peer to advertise its interface addresses.

The encoding for the Address message is:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|   Address (0x0300)          |      Message Length           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Message ID                                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                     Address List TLV                          |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Optional Parameters                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Message ID 32-bit value used to identify this message.

Address List TLV The list of interface addresses being advertised by the sending LSR. The encoding for the Address List TLV is specified in Section "Address List TLV".

Optional Parameters No optional parameters are defined for the Address message.

3.5.5.1. Address Message Procedures​

An LSR that receives an Address message uses the addresses it learns to maintain a database for mapping between peer LDP Identifiers and next hop addresses; see Section "LDP Identifiers and Next Hop Addresses".

When a new LDP session is initialized and before sending Label Mapping or Label Request messages, an LSR SHOULD advertise its interface addresses with one or more Address messages.

Whenever an LSR "activates" a new interface address, it SHOULD advertise the new address with an Address message.

Whenever an LSR "de-activates" a previously advertised address, it SHOULD withdraw the address with an Address Withdraw message; see Section "Address Withdraw Message".

If an LSR does not support the Address Family specified in the Address List TLV, it SHOULD send an Unsupported Address Family Notification to its LDP signaling an error and abort processing the message.

An LSR may re-advertise an address (A) that it has previously advertised without explicitly withdrawing the address. If the receiver already has address binding (LSR, A), it SHOULD take no further action.

An LSR may withdraw an address (A) without having previously advertised it. If the receiver has no address binding (LSR, A), it SHOULD take no further action.