Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 388)

364 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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MPLS LDP-IGP synchronization
2
Transit LSR specific processing
For those LDP cross-connects that can be recovered as part of LDP GR, there is no traffic loss for
those application using those tunnels if and only if the GR helper (example: downstream neighbor)
re-advertises the same label and upstream neighbor also support LDP GR procedure as well.
LDP ECMP (transit only)
The ability to preserve the LDP ECMP transit cross-connects depends on the route information
received from RTM during the recovery phase. In the case where the number of ECMP provided by
RTM for a route is larger than the LDP load-sharing configuration (for example, the IP load-sharing
configuration is larger than LDP load-sharing configuration), the paths are preserved as long as the
route provided by RTM, before recovery time expires, contains the installed paths.
LDP over RSVP (transit only)
RSVP GR is not supported. Therefore, when an RSVP tunnel goes down due to MP failover, LDP
cross-connects using the RSVP tunnel is not preserved as part of LDP GR support.
LDP over GRE (transit only)
LDP GR treats GRE tunnel interfaces as regular physical interfaces. When the GRE tunnel interface
up indications and route using the GRE tunnels are received before the GR recovery timer expired,
LDP over GRE tunnel cross-connects is preserved.
Graceful Restart helper-only mode
A router that is configured as GR helper-only indicates to its peers that forwarding state is not
preserved by sending an initialization message with the Reconnect time and the Recovery Time set
to 0 in FT session TLV.
Configuring LDP graceful restart (GR)
By default LDP GR is disabled. It can be enabled globally under the LDP configuration. When LDP
GR is enabled, the Brocade NetIron CES and Brocade NetIron CER routers are in helper mode only.
The Brocade MLX series and Brocade NetIron XMR routers can act either as a restarting router or a
GR helper.
With LDP GR enabled, the router waits until it receives an LDP Initialization message from its
neighbor to know whether it must delete its states or start the LDP GR recovery procedure. When
LDP GR is enabled, it is applicable to all LDP sessions regardless of the adjacency type exists
between the neighbors.
Brocade(config)# router mpls
Brocade(config-mpls)# ldp
Brocade(config-mpls-ldp)# graceful-restart reconnect-time 150
Brocade(config-mpls-ldp)# graceful-restart recovery-time 240
Syntax: [no] graceful-restart [helper-only] [reconnect-time seconds] [max-neighbor-reconnect-time
seconds] [recovery-time seconds] [max-neighbor-recovery-time seconds]