3. SR Nodes

3. SR Nodes

There are different types of nodes that may be involved in segment routing networks: SR source nodes that originate packets with a segment in the destination address of the IPv6 header, transit nodes that forward packets destined to a remote segment, and SR segment endpoint nodes that process a local segment in the destination address of an IPv6 header.

3.1. SR Source Node

A SR source node is any node that originates an IPv6 packet with a segment (i.e., SRv6 SID) in the destination address of the IPv6 header. The packet leaving the SR source node may or may not contain an SRH. This includes either:

• A host originating an IPv6 packet, or

• An SR domain ingress router encapsulating a received packet in an outer IPv6 header, followed by an optional SRH.

It is out of the scope of this document to describe the mechanism through which a segment in the destination address of the IPv6 header and the Segment List in the SRH are derived.

3.2. Transit Node

A transit node is any node forwarding an IPv6 packet where the destination address of that packet is not locally configured as a segment or a local interface. A transit node is not required to be capable of processing a segment or SRH.

3.3. SR Segment Endpoint Node

An SR segment endpoint node is any node receiving an IPv6 packet where the destination address of that packet is locally configured as a segment or local interface.