SRv6 Nodes

SRv6 Node Roles

SRv6 nodes perform the following roles:

• Source SRv6 node: a source node that encapsulates packets into SRv6 packets
• Transit node: an IPv6 node that forwards SRv6 packets but does not perform SRv6 processing
• SRv6 segment endpoint node: a node that receives and processes SRv6 packets in which the destination IPv6 address is the node's local SID or local interface address

A node's role is determined by the task it performs in SRv6 packet forwarding. A node can play different roles. For example, a node can be the source node on one SRv6 path while also being a transit or endpoint node on another SRv6 path.

On the network shown in Figure 3-15, the SRv6 source node encapsulates packets into SRv6 packets, the transit node processes and forwards the packets as common IPv6 packets, and the endpoint nodes process SRv6 SIDs and SRHs in the packets.

Figure 3-15 SRv6 nodes

Endpoint Node Behaviors

Behaviors performed by endpoint nodes are determined by instructions specified by SIDs. Such instructions include data packet forwarding, encapsulation, and decapsulation. They are called End series instructions because they are executed by SRv6 endpoints.

For details about common instructions, see SRv6 Segments.

Transit Node Behaviors

Transit nodes do not need to parse SRv6 SRHs. Table 3-2 lists the common behaviors of transit nodes, where T indicates transit.

Transit series instructions are triggered by IPv6 addresses that are neither local interface addresses nor local SRv6 SIDs advertised by nodes. For example, assume that a T.Encaps behavior policy is configured on a node, with the triggering condition being IPv6 addresses in the network segment 2001:DB8:100::/64. When the node receives the data packets carrying IPv6 addresses in that network segment, the policy is triggered. The node then performs the T.Encaps behavior by inserting the corresponding outer IPv6 packet header and SRH and searches the IPv6 routing table for a route matching the first SRv6 SID to forward the packets.

Flavors

Flavors are behaviors defined to enhance the End series instructions. They are supplements to endpoint and transit node behaviors. Flavors are optional and will change the End series instructions once used, meeting diverse service requirements. Table 3-3 lists the common flavors and their functions.