Genie's Tech Blog

Where knowledge has no dimensions

Scalable EoMPLS or EoMPLS

Hello Friends, I am back with yet another interesting topic. Today I am going to discuss on EoMPLS. EoMPLS or Scalable EoMPLS is a L2 point-to-point service between two service instances on different systems. Like Local Connect it doesn't use any MAC learning and it's solely between 2 points. It also doesn't require any global VLAN resource (this applies to scalable EoMPLS only). Before we move further, lets understand what is EVC and Local Connect: By using the EVC framework you can combine m... [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 a... [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 ... [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 ... [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.  Inte... [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 ba... [More]

Anycast-RP - The Application of MSDP

Hey Friends,  I am back with yet another post on Multicast. But, this time its about Anycast RP. But before we try to understand what is Anycast RP and how does it work, its more important to learn about MSDP. Multicast Source Distribution Protocol (MSDP) allows multicast sources of a group to be known to all Rendezvous points (RP) in different multicast domains. MSDP is a mechanism that allows RPs to share information about active sources. RPs know about their sources and receivers in th... [More]

Multicast Equal Cost Multipath (ECMP)

Hello Friends,  Its been a long while that I posted something interesting on my blog. Here comes something that might interest you. Today I am going to discuss on Multicast ECMP feature. But before we discuss this feature, lets first define the problem that we are trying to solve so that we know why we need this feature. Problem Definition: Currently if there are multiple equal-cost paths towards a PIM source or RP, only one of them will be selected as the RPF path. PIM will send joins o... [More]

Loop Free Alternate Fast-Reroute - IP LFA FRR

Hello Friends,  I am back with yet another discussion on a very interesting topic - IP LFA FRR. But before we discuss about this, lets first discuss the what was the need for such development. Problem: A change in network topology upon a failure triggers network wide convergence. For example, when a local link fails, a router currently must signal the event to its neighbors via the IGP, re-compute new primary next-hops for all affected prefixes, and then install those new primary next-ho... [More]

Reversible NAT

Hello Friends, Today I am going to discuss regarding reversible NAT.  Reversible NAT can be used in two situations 1) In dynamic NAT with route-map option and a NAT pool is being used R3(config)#ip nat inside source route-map MAP pool POOL ? mapping-id Associate a mapping id to this mapping overload Overload an address translation reversible Allow out->in traffic vrf Specify vrf When used in dynamic NAT, the reversible option is only usable after some is generated from insid... [More]