Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 136)

112 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
53-1003031-02
RSVP IGP synchronization
1
Limitations
The RSVP IGP synchronization feature allows RSVP to react to an IGP neighbor down event. It does
not allow RSVP to detect that a neighbor node has gone down. For example, when a pair of
RSVP/IGP routers are connected with parallel links, detecting one neighbor down does not actually
mean that the entire neighbor node has gone down.
Globally enabling RSVP IGP synchronization
This command globally enables the handling of an IGP neighbor down event by MPLS. This
command can be executed on the fly and takes effect immediately. It is possible to enable handling
of neighbor down events for IS-IS.
Configuration example
By default, RSVP does not handle IGP neighbor down events. RSVP IGP synchronization must be
enabled to handle an IGP neighbor down event.
To configure RSVP IGP synchronization feature, the following commands need to be executed. The
following command enables RSVP to handle IGP neighbor down events for IS-IS.
Note that commands to configure basic MPLS are not included below.
Brocade_Dut-2-XMR23# conf t
Brocade_Dut-2-XMR23(config)# router mpls
Brocade_Dut-2-XMR23(config-mpls)# policy
Brocade_Dut-2-XMR23(config-mpls-policy)# handle-isis-neighbor-down
Syntax: [no] [handle-isis-neighbor-down | handle-ospf-neighbor-down]
Limitations
1. This feature is independent of MPLS traffic engineering configurations. Irrespective of MPLS
traffic engineering configuration (OSPF or IS-IS), this feature allows MPLS (RSVP) to handle IGP
neighbor down events and take action, such as tearing down the associated RSVP sessions.
For example, when IS-IS is configured as MPLS TE protocol, the user can still configure MPLS to
handle an OSPF neighbor down event (and vice versa).
2. An IGP neighbor down event is handled only by the RSVP sub-component of MPLS by tearing
down the associated sessions. This event is not handled by LDP sub-component of MPLS.
3. MPLS/RSVP does not keep track of the current state of IGP neighbor. That is, when an IGP
neighbor goes down, RSVP tears down all the associated sessions. But RSVP does not prevent
bringing up any session while the IGP neighbor to RSVP next-hop is down (or not yet available).
That is, the RSVP session is brought up even when the IGP neighbor to the next-hop does not
exist.
4. An IGP neighbor down is treated as upstream neighbor down or downstream neighbor down
event by RSVP, depending upon the direction of the LSP. When a downstream IGP neighbor
goes down, it results in an LSP teardown or FRR switchover, whichever is applicable.
5. MPLS receives and processes an IGP neighbor down event only for the cases when an IGP
neighbor goes down because of hellos not received from the peer.