Tech Library
L2VPN – LDP based L2VPN
1. Intro LDP based L2VPN, often referred as Martini L2VPN, is used for connectivity of customer attachment circuits across the provider MPLS network. A L2VPN is a point-to-point connection between two PE routers. This type of VPN emulates transparent L2 services for the customers. Normally the L2 attachment circuits on each end are the same […]
L3VPN – Hub & Spoke VPN: One Interface
1. Intro In an MPLS L3VPN, Hub-and-Spoke is a VPN topology where spoke sites cannot communicate directly with each other. Traffic between spokes must pass through the hub PE/site. This is commonly used when the hub provides centralized firewalling, Internet access, shared services, security inspection, or centralized routing. The are two main categories for configuring […]
L3VPN – Hub & Spoke VPN: Two Interfaces
1. Intro In an MPLS L3VPN, Hub-and-Spoke is a VPN topology where spoke sites cannot communicate directly with each other. Traffic between spokes must pass through the hub CE. This is commonly used when the hub provides centralized firewalling, Internet access, shared services, security inspection, or centralized routing. The are two main categories for configuring […]
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 […]