What's segment Routing?

What’s Mean by segment routing and its benefits over tradition routing??

Hello Muhammad

Segment routing is a type of source routing, and in order to understand it, it is important to first understand source routing.

Source routing is a routing methodology that allows the sender to either partially or fully determine the route a packet will take through the network. This is in contrast to traditional routing where routing decisions are made incrementally at each router/node along the path. This allows for easier troubleshooting and allows a host to “know” all of the possible paths to the destination.

Segment routing is a type of source routing that is being developed by the IETF. In a segment routed network, an ingress router may prepend a header to packets that contain a list of segments, which are instructions that are executed on subsequent routers in the network. These instructions may be forwarding instructions, such as an instruction to forward a packet to a specific destination or interface.

Segment routing works on top of IPv6 or MPLS. An excellent description of this mechanism can be found at the following Cisco documentation.

I hope this has been helpful!


Hi Muhammad,

Segment routing is a source based transport technology that provides simplicity, scalability and 100% protection on main and backup links. It uses segments behind it to work.

There are two types of segments: IGP segments and BGP segments.

Segment routing is also designated by SR and it has some beneffits than traditional IP/MPLS networks, as described bellow:

1 - Scalability
2 - Simplicity
3 - Zero microloops
4 - SDN support
5 - Network Programability for IPv6 (SRV6)

In traditional IP/MPLS networks there is something we call microloop, it happens more on ring topology, MPLS try to solve it with Loop Free Alternate but do not guarantee 100% link protection, SR uses Topology Independent Loop Free Alternate (TI-LFA), that in case of link failure do not wait for IGP convergence… TI-LFA informs about the failure in less than 50 mili second eliminating microloop and giving 100% of link protection in all cases.

Feel free to contact me for more details.

Nilton de Matos
CCIE RnS #61356
+244 921 300 811

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