Srv6---is-is extension

At present, the most commonly used network of operators IGP Agreement is IS-IS and OSPF, By extending the IS-IS and OSPFv3 The agreement carries SRv6 Information , Can achieve SRv6 Function of control plane , No more maintenance RSVP-TE、LDP Etc. control plane protocol . From this point of view ,SRv6 The network control plane is simplified .
Some operators are deploying SRv6 When it comes to the Internet , take IGP from OSPF The agreement is replaced by IS-IS agreement . This is because OSPFv3 agreement （ Support IPv6） and OSPF agreement （ Support IPv4） Are not compatible , Network from IPv4 Upgrade to IPv6, Regardless of OSPFv3 The agreement still adopts IS-IS agreement , Are introducing new protocols , So in this case , Operators prefer to adopt IS-IS agreement , In this way, it is gradually unified IGP.

IS-IS SRv6

For support SRv6,IS-IS The protocol needs to publish two types SRv6 Information ：Locator Information and SID Information .Locator Information is used to help other nodes in the network locate the publishing site SID The node of ;SID Information is used to fully describe SID The function of , Such as SID The binding of Function Information .

Release Locator Routing information for

stay SRv6 In the network ,IS-IS The agreement passed two TLV To release Locator Routing information for ：SRv6 Locator TLV and IPv6 Prefix Reachability TLV

SRv6 Locator TLV

SRv6 Of Locator Must pass SRv6 Locator TLV Release it , Others have SRv6 The ability of IS-IS The device received TLV in the future , Issue the corresponding Locator The network segment is routed to the local forwarding table , No, SRv6 The ability is not distributed to the public .
SRv6 Locator TLV contain Locator Prefix and mask of , For publishing Locator Prefix . Through the TLV, Others in the network SRv6 Nodes can learn Locator The routing ;SRv6 Locator TLV In addition to carrying the information used to guide the routing , It also carries information that does not need to be associated IS-IS Neighbor node SRv6 SID, for example End SID.

IPv6 Prefix Reachability

Locator The corresponding network segment routes can also be routed through Prefix Reachability TLV 236/237 Release it , In order to I won't support it SRv6 The equipment Can send and forward table items , To support and SRv6 The nodes form a network together . If the device receives Prefix Reachability TLV and SRv6 Locator TLV, be Prefix Reachability TLV priority of use .
IPv6 Prefix Reachability TLV And SRv6 Locator TLV Have the same prefix and mask .IPv6 Prefix Reachability TLV yes IS-IS The agreement already exists TLV, Ordinary IPv6 node （ I won't support it SRv6 The node of ） Can also handle this TLV. therefore , Ordinary IPv6 Nodes can also pass through this TLV Generate Locator route （ The instruction message is forwarded to the release Locator Routing of nodes ）, To support and SRv6 The nodes form a network together .

Release EndPoint Function Information

IS-IS Another function of the protocol is to SRv6 SID Information and SID Corresponding SRv6 Endpoint Node behavior information is passed through IS-IS Types of agreements SID Sub-TLV Spread out , For path / The service programming unit programs the network , IS-IS released SRv6 Endpoint Function.

Examples of experimental environments

To be added ...