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]

BGP RT Constrained Route Distribution

For Handling unnecessary processing of prefixes of RT which are not imported on the PE routers we use the feature called Route-Target Constraint. With Route Target Constraint (RTC), the RR sends only those VPN4/6 prefixes to the PE that the PE has VRF importing those specific route-targets. [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 Affinity

Hello Friends, Today, i am going to have an interesting discussion on Coloring concept in MPLS TE which is actually implemented through Affinity value and mask. You must have already read in my previous posts as how MPLS TE works. Today, we will be seeing how Affinity works and what is it used for. Before we start off with Affinity, lets first discuss the MPLS TE property called Attribute-Flag. Its a 32-bit bitmap on a link that can indicate the existence of up to 32 separate properties on that link. The default value of this property is 0x0. The attributes can vary from 0x0 to 0xFFFFFFFF. Th... [More]

Multicast VPN (mVPN)

Hello Friends, Today, I will be discussing about Multicast VPN (MVPN) in which I will be explaining how it works with an example and help you troubleshoot mVPN issues on 7600 platform. As a pre-requisite, I assume everyone understands basic multicast concepts and different PIM modes specially PIM SP (Sparce Mode) and also Multicast VPN concept. First of all we, its impotant to understand that Multicast forwarding is opposite of Unicast forwarding. Unicast is concerned about where the packet is going where as Multicast is concerned about where the packet came from. Multicast uses Reverse Path ... [More]

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 multiple different services from different physical ports, i.e. when using multipoint bridging (aka b... [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]