Label Exchange; Other Reasons For Label Actions - Alcatel-Lucent 7450 Manual

Ethernet service switch

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Label Exchange

Since TCP is back-pressured by the receiver, it is necessary to be able to push that back-pressure

all the way into the protocol. Packets that cannot be sent are buffered on the session object and re-

attempted as the back-pressure eases.

Label Exchange

Label exchange is initiated by the service manager. When an SDP is attached to a service (for

example, the service gets a transport tunnel), a message is sent from the service manager to LDP.

This causes a label mapping message to be sent. Additionally, when the SDP binding is removed

from the service, the VC label is withdrawn. The peer must send a label release to confirm that the

label is not in use.

Other reasons for label actions include:

MTU changes: LDP withdraws the previously assigned label, and re-signals the FEC with

the new MTU in the interface parameter.

Clear labels: When a service manager command is issued to clear the labels, the labels are

withdrawn, and new label mappings are issued.

SDP down: When an SDP goes administratively down, the VC label associated with that

SDP for each service is withdrawn.

Memory allocation failure: If there is no memory to store a received label, it is released.

VC type unsupported: When an unsupported VC type is received, the received label is

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