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MPLS routers

Unanswered Question
Jul 27th, 2013
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what are series will be used for MPLS P-End and PE-End router,?


used of ip cef commands?


special type area in Eigrp?


BGP send community attribute?


short note for BGP..


           Tom is my interview please provide the details to explain it well. Short and simple.. dont provide cisco link to read it....

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Peter Paluch Sat, 07/27/2013 - 12:40
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Hi Dinesh,


I am wishing you all the very best for your interview but please note that the information you will gain through these questions is very shallow and it is not going to present you in a good light in the interview. You should indeed try to learn about these technologies in deep.


what are series will be used for MPLS P-End and PE-End router,?


This depends on the features and services you want to provide to your customers, plus on the required performance of the routers. Even software-based 1841 routers can be used in a lab to create a complete MPLS network and provide a fairly wide range of MPLS services including Layer2 VPNs (pseudowires), Layer3 VPNs, Carrier-Supporting-Carrier scenarios, MPLS Traffic Engineering, 6PE and 6VPE. However, the real performance of such network would be very low.


In real networks, PE routers used are usually Cisco 7200, 7600, ASR1000 and ASR9000. All these routers can also be used as P routers, plus you will find 10000, 12000 and CRS series routers in service provider backbones.


used of ip cef commands?


CEF is a key component of Cisco's implementation of MPLS. In order for MPLS to be used, you must activate and run CEF. Apart from that, there is no specific CEF tweaking necessary, at least to my best knowledge.


special type area in Eigrp?


I do not understand this question. EIGRP does not have areas.


BGP send community attribute?


BGP communities are not generally required for MPLS. However, if running MPLS L3VPN service, the route target is encoded as an extended community attribute, therefore, in MPLS L3VPNs, Cisco automatically enables the send-community extended with each neighbor in an VPNv4 address family.


short note for BGP..


Please clarify this question.


Best regards,

Peter

Dinesh Kumar Ma... Sun, 07/28/2013 - 02:21
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thanks for reply..



I meant to ask eigrp area means?


we have eigrp stub features...(in ospf stubby area, totally stubby area, NSSA and totally NSSA). similar to eigrp any features are there like eigrp stub ?



short note of BGP means.. i am asking BGP? packets of BGP, (open,session update,active) similary explain about.. why we using this protocol over other protocol.. why  we cant use eigrp in back bone(ISP side).. what is necassary of this protocol...

Peter Paluch Sun, 07/28/2013 - 03:49
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Hello Dinesh,


we have eigrp stub features...(in ospf stubby area, totally stubby area,  NSSA and totally NSSA). similar to eigrp any features are there like  eigrp stub ?


From this formulation, I do not understand whether you want me to explain the EIGRP Stub feature, or whether you want me to explain OSPF area types. Can you indicate this more precisely?


packets of BGP, (open,session update,active) similary explain about.. why we  using this protocol over other protocol.. why  we cant use eigrp in  back bone(ISP side).. what is necassary of this protocol...


BGP uses 5 types of packets:


  • Open - used when two BGP neighbors are establishing a new adjacency
  • Keepalive - used to verify whether the BGP neighbors are still up and listening
  • Update - used to carry and withdraw routing information
  • Notification - used to close the adjacency, also indicating the reason why it is being closed
  • Route Refresh - used to request the neighbor to resend all routes of a particular protocol family


The reason we use BGP is that it was from the very beginning designed to carry virtually unlimited amount of routing information, and even more, it can carry information about multiple types of routes (IPv4 unicast, IPv6 unicast, IPv4 multicast, IPv6 multicast, VPNv4, VPNv6, CLNP, ...) in a single session while keeping them perfectly separated. It assigns multiple attributes to individual routes, allowing you as an administrator to powerfully influence the distribution of the routing information and the selection of the best path. Similar tools are not available in IGP protocols. Also, the paradigm in BGP operation is not based on automatic discovery of neighbors and maintaining adjacencies to each possible neighbor, rather, the peerings always have be defined on a pairwise basis in configuration and can be established between routers that are not directly connected.


Note, however, that within an autonomous system, we still need to run an IGP, such as OSPF, IS-IS, EIGRP or even RIPv2 along with BGP. The reason is twofold: first of all, the IGP provides a router running BGP with the list of networks reachable inside the autonomous system that the BGP can import and advertise further. Second, because BGP sessions within an autonomous system are established between remote routers, there must first be a route from a BGP router to its remote peer, and that route is comfortably provided by the IGP.


Best regards,

Peter

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