Link Flapping

Traffic engineering is one of the most interesting use cases for Segment Routing. Traffic engineering has been a hard and complex problem especially in large networks with multiple routing domains. In this post I’ll look into how SR traffic engineering addresses some of these issues as well as demonstrate them on Cisco IOS XR. Traffic engineering Traffic engineering (TE) is a mechanism for controlling path that the traffic takes through the network to the destination. [Read More]

Segment Routing is as of mid 2017 available on multiple vendors service provider routing platforms (Cisco, Juniper, Nokia, Arista). In this post I’m going to show how to configure MPLS Segment Routing in Cisco IOS XR as well as take a closer look at the adjacency and prefix segments. Topology The example topology consist of six XRv routers with IP addresses configured as seen in the figure above. [Read More]

In this post I’m going to explain different types of segments used in Segment Routing. I’m concentrating on the MPLS data plane since it is more mature and widely available than SRv6. Global and Local Segments Segment Routing segments can global or local. Global segment instruction is supported by all nodes in a Segment Routing domain. Global segment is represented as a label value calculated by adding index value to SR Global Block (SRGB). [Read More]

Segment routing is a new routing mechanism where the source node specifies a forwarding path by encoding it in the packet header as ordered list of instructions. These instructions are called segments. The most general segment instruction is to forward packet to a certain node through the shortest path or through certain link, but segment can also be used for example to forward packet through certain service or service chain. [Read More]