Genie's Tech Blog

Where knowledge has no dimensions

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]

Inter-AS MPLS TE

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]

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]

NSF, NSR and GR

Hello Folks... Welcome back again. I was reading through some High Availability features and came across a good discussion on NSR (Non-Stop Routing), NSF (Non-Stop Forwarding) and GR (Graceful Restart). Just thought of sharing the same in simple words. But, first we'll understand the need for the same. Most of the high end routers separate the Control plan with the Forwarding plane with separate components viz. memory and processors. The control plane runs the routing protocols, maintains the databases necessary for route processing and derives the FIB (Forwarding Information Base) which is ... [More]

BFD : Concept

Introduction In both Enterprise and Service Provider networks, the convergence of business-critical applications onto a common IP infrastructure is becoming more common. Given the criticality of the data, these networks are typically constructed with a high degree of redundancy. While such redundancy is desirable, its effectiveness is dependent upon the ability of individual network devices to quickly detect failures and reroute traffic to an alternate path. This detection is now typically accomplished via hardware detection mechanisms. However, the signals from these mechanisms are not alwa... [More]