Segment Identifiers
Segments are identified by a Segment Identifier (SID) which is an unsigned 32-bit integer. Because the MPLS data plane is used, the segments are identified by a 20-bit integer, leaving the 12 left-most bits of the SID unused. A SID has an absolute value and index (label) allocated for the segment. Because the SRGB is the same across the entire domain, all nodes identify the segment with the same absolute value.
Prefix SID Absolute Value
Specify an absolute SID-value for each node to create a specific prefix SID within the configured SRGB range.
When a Prefix-SID is configured as absolute, the same value is used for packet-switching.
(config-if)#prefix-sid absolute <16-1048575>
Prefix SID Index Value
Specify an index SID-index for each node to create a prefix SID based on the lower boundary of the SRGB and the index.
(config-if)#prefix-sid index <0-1048575>
This index value will be used for calculating absolute MPLS label by adding base value of SRGB. In case of default SRGB (16000-23999) if index value is 1000, the MPLS label value will (16000 + 1000) = 17000.
Last modified date: 06/27/2023