Genie's Tech Blog

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MPLS TE: Auto-Tunnel Mesh Groups

Hello Friends Today, I am going to discuss about one of the interesting features on MPLS TE which is the Auto-Tunnel feature which gives us the capability to create TE tunnels automatically based on the destination list. The Auto-Tunnel feature provides automatic creation of one-hop primary TE tunnels (Auto-Tunnel Primary), and both nhop and nnhop FRR backup TE tunnels (Auto-Tunnel Backup).  Auto-Tunnel Primary and Backup can be enabled separately via CLI configuration. The Auto-Tunnel Primary feature, once enabled, causes the router to dynamically create one-hop tunnels to directly... [More]

MPLS TE tunnels without IGP

Hello Friends, i was trying to test out few things on MPLS TE and then i came across an observation that you can build the MPLS TE tunnel without running an IGP (Interior Gateway Protocol). Later on, I made another observation that the MPLS TE tunnel would come up even if we don't have RSVP configured on the interfaces. Though both these tunnels and configurations totally defy the facts that we have read about MPLS Traffic-engineering and also defy the purpose of MPLS TE tunnels but still this stuff seems to be working out. Lets consider a sample topology say: R1 ---- R3 ---- R4 ---- R6 whe... [More]

CSPF - The TE Algorithm

Hello Everyone, Today I thought of sharing with you some understanding on CSPF Algorithm. CSPF stands for Constraint Shortest Path First. This constraint-based routing is executed online by Ingress Router. The CSPF calculates an optimum explicit route (ER), based on specific constraints. The path is computed using traffic engineering database which takes the extensions of OSPF and IS-IS as input. The resulting route is then used by RSVP-TE. The CSPF in particular and any constraint based routing process requires following inputs: Bandwidth requirements Hop limitations Administr... [More]