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Modifying a SRGB configuration is disruptive for traffic and may require a reboot if the new SRGB is not available entirely.Ī local segment is automatically assigned an MPLS label from the dynamic label range.
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That you use the default IOS XR SRGB range.Īllocating a non-default SRGB in the upper part of the MPLS label space increases the chance that the labels are available To avoid a potential router reload due to label conflicts, and assuming that the default SRGB size is large enough, we recommend Upon IS-IS/OSPF/BGP registration, LSD allocates the requested SRGB (either the default range or the customized range).Īfter IS-IS/OSPF/BGP have registered and their SRGB is allocated, LSD starts serving dynamic label requests from other clients. To remove this conflict, you must reload the router to release the currently allocated labels and to allocate the new SRGB.Īfter the system reloads, LSD does not accept any dynamic label allocation before IS-IS/OSPF/BGP have registered with LSD. Successful for, SRGB (16000 80000, SRGB_ALLOC_CONFIG_PENDING, 0x2) %ROUTING-ISIS-4-SRGB_ALLOC_FAIL : SRGB allocation failed: 'SRGB reservation not The following system log message indicates a label conflict: When you define a non-default SRGB range, there might be a label conflict (for example, if labels are already allocated, statically You can also configure a non-default SRGB under the IGP, but it is not recommended. By default, all IGP instances and BGP use this SRGB. We recommend that the non-default SRGB be configured under the segment-routing global configuration mode. Furthermore, a platform may limit the number of Label range is just reserved for SR and not available for other purposes. In Cisco IOS XR release 6.6.3 and later, the SRGB can be configured to any size value that fits within the dynamic label rangeĪllocating an SRGB label range does not mean that all the labels in this range are programmed in the forwarding table. In Cisco IOS XR release earlier than 6.6.3, the SRGB can have a maximum configurable size of 262,143.
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The SRGB starting value can be configured anywhere in the dynamic label range space (16,000 to 1,048,575). The default SRGB range is not large enough to accommodate all required prefix SIDs.Ī non-default SRGB can be configured following these guidelines: Non-IOS XR nodes with a SRGB range that is different than the default IOS XR SRGB range. There are instances when you might need to define a different SRGB range. This size, and assuming one loopback prefix per router, an operator can assign prefix SIDs to a network with 8000 routers. The default SRGB in IOS XR has a size of 8000 starting from label value 16000. Is also supported but is not recommended. Using a heterogenous SRGB (meaning, a different SRGB range of the same size across nodes) To keep the configuration simple and straightforward, we strongly recommended that you use a homogenous SRGB (meaning, the For example, considering an SRGB range of 16,000 to 23,999, a prefix 1.1.1.65/32 with prefix-SID index of 65 is assigned the label value of 16065.
DEFAULT ROUTER CONFIGURATION PLUS
The MPLS label assigned to a prefix is derived from the Prefix-SID index plus Zero-based, meaning that the first index is 0. The prefix-SID index points to a unique label within the SRGB range. A prefix-SID isĪdvertised as a domain-wide unique index. The Segment Routing Global Block (SRGB) is a range of labels reserved for Segment Routing global segments. Setup a Non-Default Segment Routing Local Block Range.Setup a Non-Default Segment Routing Global Block Range.Routing Local Block (SRLB) are label values preserved for segment routing in the LSD. The Segment Routing Global Block (SRGB) and Segment Local label allocation is managed by the label switching database (LSD). Configure Segment Routing Global Block and Segment Routing Local Block