segment-routing ipv6 locator (OSPFv3 view)

Usage Scenario

In a scenario where OSPFv3 is deployed on the public network, for example, in an SRv6 BE scenario, after SRv6 is enabled for OSPFv3, intra-AS LSAs are advertised, carrying the prefix information corresponding to the configured locator. NULL0 routes with the corresponding prefix are delivered, and End and End.X SIDs are generated based on the specified locator. The SRv6 SIDs generated by OSPFv3 are added to the local SID table and also advertised to neighbors through OSPFv3 LSAs. The locator prefix algorithm and End SIDs are advertised through locator LSAs, and End.X SIDs are advertised through E-Router LSAs.

Different parameter combinations in this command have different functions. The details are as follows:

• segment-routing ipv6 locator locator-name: enables OSPFv3 SRv6 and dynamic SID allocation. SIDs must be allocated within the locator range.

• segment-routing ipv6 locator locator-name auto-sid-disable: enables OSPFv3 SRv6 and disables dynamic SID allocation so that SIDs are statically allocated within the locator range.

• undo segment-routing ipv6 locator locator-name [ auto-sid-disable ]: deletes all OSPFv3-allocated dynamic SIDs and advertised static SIDs within the specified locator range. In this case, auto-sid-disable is an optional parameter, and the configuration effect is the same regardless of whether auto-sid-disable is specified.

During SRv6 SID allocation, if a static opcode is configured, the static opcode is preferentially used to form a static SID. If no static opcode is configured, a SID is dynamically allocated. The process of OSPFv3 SRv6 SID allocation is as follows:

• Configure a locator in the SRv6 view, and run the segment-routing ipv6 locator command in the IS-IS process view to enable SRv6 and reference the locator. In an OSPFv3 process, only one locator is allowed to advertise End SIDs or End.X SIDs.

• OSPFv3 can obtain statically configured End and End.X SIDs from the specified locator range and advertise them using LSAs.

A static End.X SID can be advertised only when it matches a neighbor. If the next hop configured through the End.X SID is a global address, the two ends of the OSPF neighbor must support the advertisement of the global address through the E-Router LSA extension.

• OSPFv3 allocates an End SID to each locator in the range of the dynamic segment based on locator configurations. No-flavor, PSP, PSP-USP-USD SIDs are all allocated.

• Specify OSPFv3 neighbors for interfaces. OSPFv3 allocates an End.X SID to each neighbor in the range of the dynamic segment based on locator configurations. No-flavor and PSP SIDs are allocated.

OSPFv3 can reference a compression locator and advertise the prefix routes of the locator through Intra-Area-Prefix-and locator LSAs. However, OSPFv3 does not support the compression capability or the advertisement of compressed SIDs. Details are as follows:

• Supports the allocation of uncompressed dynamic End and End.X SIDs to a compression locator. The SIDs are allocated from the compression segment, and then non-compression entries are delivered. The SIDs are advertised in LSAs as uncompressed SIDs without the C-Flag.

• For the static opcode configured for a compression locator:

If the opcode configuration does not contain the compress parameter, SIDs can be advertised as uncompressed ones without the C-Flag.

If the opcode configuration contains the compress parameter, non-flavor, PSP, and PSP-USP-USD SIDs are advertised in LSAs as uncompressed ones without the C-Flag. PSP-USP-USD-COC SIDs cannot be advertised.

• The OSPFv3 SRv6 SID Structure Sub-TLV cannot be carried during SID advertisement.

• After OSPF is bound to a locator, the locator cannot be changed from a non-compression one to a compression one or from a compression one to a non-compression one.

OSPFv3 can be bound to a compression locator to provide forwarding routes for static SRv6 compressed SIDs.

In scenarios where compression is to be supported in the future, compression locators can be used when OSPFv3 SRv6 is deployed for the first time. Although compression is not currently supported, this can avoid the large number of deployment changes caused by locator switching to be performed to support compression in the future.

Other constraints:

• Locators using a non-zero algorithm cannot be referenced.

• Locators cannot be configured for OSPFv3 VPN processes.

Prerequisites

Before configuring the segment-routing ipv6 locator command, complete the following configuration:

• Run the segment-routing ipv6 command in the system view to enable global SRv6.
• Run the command locator ipv6-prefix command in the segment-routing ipv6 view to configure a locator.