With Vignesh R.P.
Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn and ask questions about configuring and troubleshooting the Intermediate System-to-Intermediate System (IS-IS) routing protocol for IP on Cisco routers.
The IS-IS routing protocol is an Interior Gateway Protocol (IGP) standardized by the Internet Engineering Task Force (IETF) and commonly used in large service provider networks. IS-IS may also be deployed in extremely large enterprise networks. IS-IS is a link-state routing protocol, providing fast convergence and excellent scalability. Like all link-state protocols, IS-IS is very efficient in its use of network bandwidth.
Vignesh R. P. is a customer support engineer in the Cisco High-Touch Technical Support center in Bangalore, India, supporting Cisco's major service provider customers in routing and Multiprotocol Label Switching (MPLS) technologies. His areas of expertise include routing, switching, and MPLS. Previously at Cisco he worked as a network consulting engineer for enterprise customers. He has been in the networking industry for eight years and holds CCIE certification in the routing and switching and service provider tracks.
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Vignesh might not be able to answer each question due to the volume expected during this event. Remember that you can continue the conversation in Network Infrastructure, sub-community WAN, Routing and Switching discussion forum shortly after the event. This event lasts through December 20, 2013. Visit this forum often to view responses to your questions and the questions of other community members.
OSPF requires that an area be defined as a backbone area and that each other area border that backbone area. Special configuration (a virtual link) is required for any area that does not border the backbone area. IS-IS backbone routers can reside in any area. There merely must be an unbroken chain of Level 2 or Level 1/2 routers in order for the backbone to function.
Hope this helps.
Thanks & Regards,
Vignesh R P