Extreme Networks BlackDiamond 6800 MPLS, Installation And User Manual

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MPLS Module Installation and User Guide 7-21
Using ESRP with MPLS TLS
LSP Tracking
LSP tracking provides MPLS with specific ESRP selection criteria for determining the
ESRP status of a VLAN. LSP tracking is similar to route tracking and ping tracking in
ESRP. As shown in Figure 7-6, ESRP can be configured to protect the user VLAN from
disruptions in the MPLS network core. For example, LSR A and LSR B can be
configured to track an established LSP to
IP
T2
. If a network disruption causes the LSP
from LSR A to LSR C to fail, ESRP detects the condition and fails over to LSR B
(provided LSR B has an established LSP to LSR C). This type of LSP protection is
especially useful when providing ESRP redundant TLS L2 VPN services using Traffic
Engineered LSPs that take completely different paths (for example, LSP from LSR A to
LSR C and LSP from LSR B to LSR C).
Using ESRP domains, LSP tracking can be easily scaled to support several TLS VLANs
that are tunneled across an L2 VPN using a single LSP. Instead of each TLS VLAN
tracking the same LSP, all of the TLS VLANs are placed into an ESRP domain for which
there is one non-TLS VLAN, configured to track the state of the LSP. When ESRP
detects that the LSP has failed, all of the VLANs in the configured ESRP domain
transition to neutral state and the backup LSR becomes the master switch for all of the
TLS VLANs.
To configure LSP tracking, use the following commands:
config vlan < name> add track-lsp [<lsp_name> | ipaddress
< ipaddress/masklength>]
config vlan < name> delete track-lsp [<lsp_name> | ipaddress
< ipaddress/masklength> | all]
This command configures the LSPs tracked by ESRP in order to determine the ESRP
state of the specified VLAN. The
add track-lsp
command configures ESRP to track
up to eight LSPs. Fail over to the slave switch is based on the total number of
established tracked LSPs. The switch with the greatest number of established tracked
LSPs is elected the master switch for the specified VLAN. Specifying the parameter
<
lsp_name>
instructs ESRP to track the status of an RSVP-TE LSP. Specifying the
ipaddress
keyword instructs ESRP to track the LSP status for the IP prefix as defined
by the
<ipaddress/masklength>
parameter. Both types of LSPs can be tracked
simultaneously. The
delete track
-
lsp
command removes an LSP from ESRP tracking
for the specified VLAN. If you specify the
all
keyword, all configured LSPs are
removed from ESRP tracking for the specified VLAN.