Tech Library
L3VPN – auto-export
1. Intro The auto-export statement enables you to leak routes between VRF instances that are locally configured on a PE router. Auto export is always applied on the local PE router, because it applies to only local prefix leaking by evaluating the export policy of each VRF and determining which route targets can be leaked. […]
SR-MPLS – Fallback for inetcolor.0
1. Intro This is a continuation of the previous post: SR-MPLS – Static colored LSP. There we configured a colored LSP and we saw how the next-hop is installed in the inetcolor.0 table. But, what will happen if that LSP goes down? With no more valid next-hops in the inetcolor.0 table the traffic will be […]
SR-MPLS – TI-LFA
1. Intro Loop-free alternate (LFA) and remote LFA have been used to provide fast-reroute protection for several years. With LFA, a point of local repair (PLR) determines whether or not a packet sent to one of its direct neighbors will reach its destination without looping back through the PLR. In a typical network topology, perhaps […]
SR-MPLS – Anycast
1. Intro An IGP anycast segment is an IGP prefix segment that identifies a set of routers. An anycast segment enforces forwarding based on the equal-cost multipath-aware shortest-path toward the closest node of the anycast set. Within an anycast group, all the routers advertise the same prefix with the same SID value, which facilitates load […]
SR-MPLS – Computed LSP
1. Intro Another way to create an LSP is to calculate the path dynamically based on a set of traffic engineering constraints. This option uses a version of the CSPF algorithm (similar to RSVP), called Distributed CSPF (D-CSPF). The name reflects the fact that the protocol can be run on any router in the network, in contrast […]
SR-MPLS – Static colored LSP
1. Intro The ingress route of the colored LSP is installed in the inetcolor.0 or inet6color.0 routing tables, with destination-ip-address, color as key for mapping IP traffic. We will use the same test topology from the previous posts: The initial config is simple: 2. Colored LSP We want to transform our source-routing-path R1-TO-R8 to a […]
SR-MPLS – S-BFD
1. Intro In the previous post we configured a static LSP. That configuration is easy to configure but, like all static paths, cannot react to topology changes. If one of the links or nodes represented by your segments fail, then the entire path fails. Another disadvantage of this option is that it cannot inherently identify […]
SR-MPLS – Static non-colored LSP
1. Intro The segment routing architecture enables the ingress devices in a core network to steer traffic through explicit paths. You can configure these paths using segment lists to define the paths that the incoming traffic should take. SR is a control-plane architecture that enables an ingress devices in a core network to steer traffic […]
SR-MPLS – Basic Config
1. Intro Segment Routing is also known as Source Packet Routing in Networking (SPRING), and it comes in two flavors SR-MPLS and SRv6 In a segment-routed network, source routing enables the first router in a path to calculate the end-to-end path. The source router can then write a series of MPLS labels or IPv6 addresses […]
RSVP – LDP Tunneling
1. Intro You can run LDP over LSPs established by RSVP, effectively tunneling the LDP-established LSP through the one established by RSVP. To do so: To demonstrate LDP tunneling we will use the following topology: As we see in the diagram, we have 2 LDP islands. Routers R1, R2, R3 and R4 have LDP configured […]