Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 99)

Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide 75
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MPLS CSPF fate-sharing group
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primary LSP. For example, Q1, Q2, and Q3 is a collection of CSPF groups used by the primary
LSP. TE link 1 is a member of CSPF groups Q1 and Q2. Q1 has a penalty of 10, and Q2 has a
penalty 30. The total penalty of CSPF groups Q1 and Q2 is equal to 40. The total adjusted
distance for TE link 1 is equal to the native IGP cost plus 40. The penalty is only applied once to
each shared CSPF group that the TE link is associated with. The secondary LSP path is then
computed from ingress to egress using the adjusted distance of each TE link.
• When computing a backup path by selecting a bypass LSP, CSPF collects group information
from the outgoing interface used by the protected path. CSPF computation first selects the
downstream merge point in the order of preference. When there is no bypass LSP that can
reach the selected merge point, the next merge point is selected until there is at least one
bypass LSP that can reach that merge point. For each bypass LSP that can reach the merge
point, CSPF uses the collected group information to compute the total adjusted distance of
each of the bypass LSPs. The bypass LSP with the lowest adjusted distance to the merge point
is selected. When there are more than one bypass LSP with the lowest adjusted distance,
select a bypass LSP by load balancing the number of protected LSPs riding over them.
• By default, the bypass LSP metric is not considered when selecting the bypass LSP tunnel. The
CSPF computation mode of the bypass LSP metric must only be used when the bypass LSP
metric must be considered so that the bypass LSP with the lowest metric is selected as the
final bypass LSP tunnel.
Configuring a MPLS CSPF fate-sharing group
To configure a CSPF fate-sharing group, perform the following steps in router MPLS mode.
1. Specify the CSPF group computation mode for a fate-sharing group, and enable the
add-penalty option by entering the following command in MPLS policy mode.
Brocade(config-mpls-policy)# cspf-group computation-mode add-penalty
Syntax: [no] cspf-group computation-mode [add-penalty]
The cspf-group computation-mode command specifies the mode that is used when setting up
a fate-sharing group. The add-penalty parameter specifies the penalty that is added from all
CSPF groups associated with the same TE link used by the protected path. To disable the CSPF
group computation mode, enter the no form of the command.
2. Configure a CSPF fate-sharing group by assigning a name to the group. Enter the following
command in router MPLS mode.
Brocade(config-mpls)# cspf-group group3
Syntax: [no] cspf-group group-name
The cspf-group group-name command specifies the name of the fate-sharing group. The
group-name variable can be up to 128 characters. The objects that can be specified for a
fate-sharing group are interface, point-to-point link, node, and subnet. For more information on
specifying objects for a fate-sharing group, refer to
“MPLS CSPF fate-sharing group” . To disable
the configuration, enter the [no] form of the command.
NOTE
The maximum number of CSPF fate-sharing groups that can be configured on a device is 1000.