Genie's Tech Blog

Where knowledge has no dimensions


Hello Friends, Today we are going to discuss on another L2VPN implementation i.e. FroMPLS (Frame-Relay over MPLS). In the early days, when Frame-Relay service was heavily used in the customer networks, the Service Providers used to provide Frame-Relay services with the help of Frame-Relay switches like LS1010 and several others. But over the time as the technology have advanced, the Service Providers have upgraded their network to use MPLS which gives them the flexibility to provide any kind of L2 service be it PPP or FR or ATM or plain Ethernet. They don;t need to deploy specific hardware in... [More]

Inter-AS MPLS VPN - Back to Back VRF

Hello All, Today, We are going to discuss about one of the very common topics on Inter-AS MPLS VPN's i.e. Inter-AS MPLS VPNs with Back to Back VRF. We are already aware of how Intra-AS MPLS VPN's work. This has been discussed deeply in one of our previous posts (Link Below). In Inter-AS VPN, Customers connect their sites across AS boundaries. The very first and basic type of Inter-AS deployment is Back to Back VRF. In this approach, the ASBR of both AS's connect each other through multiple sub-interfaces where in each sub-interface se... [More]

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]

BGP-based VPLS Autodiscovery

Hello Everyone, I am back with yet another post on one of the topics which caught my interest on - VPLS Autodiscovery using BGP. Before we start digging in to it, lets first start by understanding what VPLS is? What is VPLS? Virtual - Multiple VPLSs can be offered over common packet switched network. Private - CE devices that belong to different VPLSs cannot interact LAN Service - CE devices that belong to given VPLS instance V, can interact through the SP network as if they were connected by a LAN. VPLS is an architecture which allows MPLS networks to provide Mu... [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]

Inter-Area MPLS TE on IOS-XR

Hello Everyone, As mentioned earlier, today I will be discussing about Inter-Area MPLS TE. In my previous blog, we already discussed regarding Inter-Domain MPLS traffic engineering and we further discussed on the Inter-AS MPLS traffic engineering. We are now going to the second form of Inter-Domain MPLS traffic engineering i.e. Inter-Area MPLS traffic engineering. Inter-Area MPLS TE is fairly simple as compared to Inter-AS MPLS TE. Also, I will be discussing this topic on IOS-XR platform. The MPLS TE Interarea Tunnels feature allows you to establish MPLS TE tunnels that span multiple Interio... [More]


Hello Everyone, Today I am going to discuss about Inter-AS MPLS Traffic-engineering (TE). Till now we have seen how MPLS behaves within a single AS but will not see the functionality and implementation of Traffic-engineering Tunels. Actually Inter-AS MPLS TE is a part of Inter-Domain Traffic-engineering in which a domain is identified as an IGP area or an Autonomous-System. In Inter-Domain TE, Head-End router lacks complete network topology to perform path computation in both cases.  Inter-Domain TE Fast-Reroute: The Inter-Domain TE FRR has the same configuration as the single doma... [More]


As we read about Layer 2 VPN's, Pseudowires, etc, there comes a need for MPLS OAM (Operations, Administration and Maintenance) mechanisms that can we can use for fault detection, administration and multiple other functions over a PW and a LSP. These functions can be used between any two LERs or LSRs and specifically in a MPLS TP environment. There are existing tools which can serve similar functions: 1. VCCV - Virtual Circuit Connectivity Verification 2. BFD MPLS 3. LSP Ping 4. BFD VCCV Note: VCCV is basically a control channel between a PWs ingress and egress points over which the connec... [More]

MPLS TE with Fast-Reroute (FRR) - Link Protection

Hey Guys, Today I have a very interesting topic to discuss. We are going to discuss about MPLS Traffic-engineering (TE) with Fast-Reroute (FRR). Actually, I came across some customer issue and I had to dig deeper into the platform level of 7600 to find out the root cause. But, then lately I realized that I should share the concept with everyone. So here it is..  MPLS Traffic-Engineering MPLS TE combines the ATM's Traffic engineering capabilities with IP's flexibility and Class-of-Service differentiation. MPLS TE tunnels are unidirectional tunnels which are build on the LSP's across you... [More]