The prefix node SID (IPv4 and/or IPv6) must be assigned for each participating Flex-Algorithm.
The Flex-Algorithm SIDs are allocated from the label block assigned to SR and configuring a special range is not required.
Use the following syntax to configure the prefix node SIDs for IS-IS Flex-Algorithms.
config>router>isis>interface
— ipv4-node-sid
— flex-algo
— ipv4-node-sid index <value>
— ipv4-node-sid label <value>
— no ipv4-node-sid
— ipv6-node-sid index <value>
— ipv6-node-sid label <value>
— no ipv6-node-sid
The following is a sample configuration output for Flex-Algorithm prefix node SIDs:
router
mpls-labels
sr-labels start 20000 end 30000
exit
interface "Loopback0"
address 10.20.1.2/32
loopback
no shutdown
exit
isis 0
segment-routing
prefix-sid-range global
no shutdown
exit
interface "Loopback0"
ipv4-node-sid index 2
passive
flex-algo 128
ipv4-node-sid index 12
exit
no shutdown
exit
The following output is an example of the Level 2 database of an advertised IS-IS:
A:Dut-B# show router isis database Dut-B.00-00 detail level 2
===============================================================================
Rtr Base ISIS Instance 0 Database (detail)
===============================================================================
Displaying Level 2 database
-------------------------------------------------------------------------------
LSP ID : Dut-B.00-00 Level : L2
Sequence : 0x9d Checksum : 0x38e9 Lifetime : 626
Version : 1 Pkt Type : 20 Pkt Ver : 1
Attributes: L1L2 Max Area : 3 Alloc Len : 1492
SYS ID : 4900.0000.0002 SysID Len : 6 Used Len : 223
……<snip>……
TE IP Reach :
Default Metric : 10
Control Info: , prefLen 30
Prefix : 10.10.10.0
Default Metric : 0
Control Info: S, prefLen 32
Prefix : 10.20.1.2
Sub TLV :
Prefix-SID Index:2, Algo:0, Flags:NnP
Prefix-SID Index:12, Algo:128, Flags:NnP
Default Metric : 10
Control Info: , prefLen 30
Prefix : 10.10.10.8
...<snip>...