Segment Routing Global Block
The Segment Routing Global Block (SRGB) is a local property of a segment routing node. In the context of MPLS, it is a set of “local labels” for global segments.
By default, OcNOS uses the same local label range (16000-23999) for all the segment routing nodes for SRGB.
If a node participates in multiple SR domains, there is one SRGB for each SR domain. In SR-MPLS, SRGB is a local property of a node and identifies the set of local labels reserved for global segments.
In SR-MPLS, using identical SRGBs on all nodes within the SR domain is strongly recommended. Doing so eases operations and troubleshooting as the same label represents the same global segment at each node.
When SRGB is not configured, the system reserves a default label range.
The SRGB default value is 16000 to 23999. The SRGB can be configured as follows:
Note: Make sure that the labels in the SRGB label range are not used by any other protocols (LDP, RSVP, BGP, static LSP, ISIS-SR policy, OSPF-SR policy). To check the label ranges configured for each of the protocols use show mpls label-space 0 and re-configure the SRGB label range with a label range that is available.
SRGB in global mode:
#conf t
(config)#segment-routing
(config-sr)#global block 30000 50000
SRGB declared in global mode can be used by either ISIS or OSPF if they do not have configured SRGB in their respective routing process level.
SRGB under ISIS:
(config)#router isis isis1
(config-router)#isis segment-routing global block <16-1048575>
SRGB under OSPF:
(config)#router ospf 1
(config-router)#ospf segment-routing global block <16-1048575>
Last modified date: 06/27/2023