Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 392)

368 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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Configurable LDP router ID overview
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Configurable LDP router ID overview
LDP protocol uses LDP messages to communicate between LDP peers for correct functioning of
LDP protocol. All LDP messages contains a LDP header which is composed of LDP version, length
of message, LDP ID, followed by message. The LDP ID for LDP protocol is composed of LSR-ID and
label space. A valid IP address is selected as an LSR-ID field.
Through NetIron Release 05.400, NetIron products select the first valid and operationally UP IP
address among all the enabled loopback interfaces as LSR-ID for LDP protocol. When IP address or
loopback interface which is used as LSR-ID goes down, LDP protocol selects the next operationally
UP IP address among all enabled loopback interface as LSR-ID else LDP protocol will be down.
Using this feature users are able to specify an IP address of their choice to used as LSR-ID for LDP
protocol.
Background
NetIron Release 05.400 LDP protocol selects the first operationally UP and valid IP address among
all the enabled loopback interfaces as the LSR-ID. When user delete this IP address from a
loopback interface, or disables a loopback interface on which IP address is configured, or deletes
the loopback interface on which IP address is configured, the LDP is disabled. It then selects the
next valid and operationally UP IP address among all the enabled loopback interfaces as LSR-ID
and enables LDP protocol.
When there is no valid IP address available to be selected as LSR-ID, the LDP protocol continues to
remain disabled until a valid IP address is configured on an enabled loopback interface.
FIGURE 47
Version PDU Length
LDP Identifier
LDP Header format
• LDP identifier: LSR-ID: label space
• LSR-ID: First available loopback interface (current behavior)
Release NetIron R05.5.00 LDP LSR-ID requirements
Configurable LDP LSR-ID allows user to configure an IP address of their choice as an LSR-ID for LDP
protocol.
Once user configure the feature with a valid IP address, LDP protocol must use the feature’s
configured value as the LSR-ID. In order to compel LDP protocol to use the new value as the LSR-ID,
LDP protocol restarts.