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Router Interface Commands
Parameters
group-name — Specifies the name of the group with up to 32 characters. The association of group
srlg-group
Syntax
srlg-group group-name value group-value
no srlg-group group-name
Context
config>router>if-attribute
Description
This command defines an Shared Risk Loss Group (SRLG) which can be associated with an IP or
MPLS interface.
SRLG is used to tag IP or MPLS interfaces which share a specific fate with the same identifier. For
example, an SRLG group identifier could represent all links which use separate fibers but are carried
in the same fiber conduit. If the conduit is accidentally cut, all the fiber links are cut which means all
interfaces using these fiber links will fail.
The user first configures locally on each router the name and identifier of each SRLG group. A
maximum of 1024 SRLGs can be configured per system.
The user then configures the SRLG membership of an interface. The user can apply SRLGs to a IES,
VPRN, network IP, or MPLS interface. A maximum of 64 SRLGs can be applied to a given interface.
When SRLGs are applied to MPLS interfaces, CSPF at LER will exclude the SRLGs of interfaces
used by the LSP primary path when computing the path of the secondary path. CSPF at a LER or
LSR will also exclude the SRLGs of the outgoing interface of the primary LSP path in the
computation of the path of the FRR backup LSP. This provides path disjointness between the primary
path and the secondary path or FRR backup path of an LSP.
When SRLGs applied to IES, VPRN, or network IP interfaces, they are evaluated in the route next-
hop selection by adding the srlg-enable option in a route next-hop policy template applied to an
interface or a set of prefixes. For insance, the user can enable the SRLG constraint to select a LFA
next-hop for a prefix which avoids all interfaces that share fate with the primary next-hop.
The following provisioning rules are applied to SRLG configuration. The system will reject the
creation of a SRLG if it re-uses the same name but with a different group value than an existing
group. The system will also reject the creation of an SRLG if it re-uses the same group value but with
a different name than an existing group.
It should be noted that only the SRLGs bound to an MPLS interface are advertised area-wide in TE
link TLVs and sub-TLVs when the traffic-engineering option is enabled in IS-IS or OSPF. IES and
VPRN interfaces do not have their attributes advertised in TE TLVs.
Parameters
group-name — Specifies the name of the group, up to 32 characters. The association of group name
value group-value — Specifies the integer value associated with the group. The association of group
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name and value should be unique within an IP/MPLS domain.
and value should be unique within an IP/MPLS domain.
name and value should be unique within an IP/MPLS domain.
Values
0 — 4294967295
7750 SR OS Router Configuration Guide
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