Cisco and Nonstop Forwarding

Nonstop Forwarding is a feature of many features in the Cisco High Availability portfolio, we shall be covering most of it later. To check Cisco High Availability portfolio: http://www.cisco.com/en/US/products/ps6550/products_ios_technology_home.html Use Cisco Feature Navigator to find information about platform support and software image support: http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp Cisco Nonstop Forwarding (NSF – AKA Graceful Restart) with Stateful Switchover (SSO – SSO is a prerequisite for NSF) is a Cisco innovation for platforms with dual route processors (Cisco 7304, 7500, ASR1000, 4500, 6500, 7600, 10000, 12000 and CRS), allowing a NSF Capable router which has experienced a hardware or software failure of an active …

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Option AB – Inter-AS MPLS VPN – The whole story (5) – Updated Dec 2008

In late 2007, Cisco introduced a new Inter-AS option; Option AB – This feature was introduced in the 12.2(33)SRC code. This feature combines the the best aspects of Option 1 (10A) and Option 2 (10B) (named type a and type b as per RFC4364 section 10 “Multi-AS Backbone”). Remember that type a (Option 1 AKA 10A) was not scalable, since a separate interface/subinterface and an eBGP session are required per each VRF on the ASBR, while it is simple, secure and per VRF QoS capable (per VRF interface/subinterface). On the other hand type b (Option 2 AKA 10B) despite being …

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Option 3 (10C): Multi-Hop MP-eBGP Between RR and eBGP Between ASBRs – Inter-AS MPLS VPN – The whole story (4) – Updated Dec 2008

This approach is considered to be the most scalable, since when compared with Option 2(10B), the ASBRs need not learn all the VPNv4 prefixes, since now the MP-eBGP session will be established between the RRs (which already have all the VPNv4 prefixes by default) rather than the ASBRs, and the ASBRs will only be responsible of exchanging the next-hop addresses of the VPNv4 prefixes via eBGP. Although I believe each AS having reachability to all the internal next-hops in the other AS has an implicit security concern, however practically speaking this option is normally deployed only when both autonomous systems …

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Option 2 (10B): ASBR-to-ASBR / MP-eBGP for VPNv4 – Inter-AS MPLS VPN – The whole story (3) – Updated Dec 2008

With the ASBR-to-ASBR approach, the ASBRs use MP-eBGP to peer with each other to transport VPNv4 routes between the autonomous systems, and the VPN packets are transported as labeled packets between the ASBRs, unlike Option 10A. As we are going to see later in details, the main difference between both sub-options 2a and 2b and sub-option 2c is that simply the MP-eBGP session between the ASBRs uses the directly connected interfaces, while in option 2c the MP-eBGP peering is done using loopback interfaces. This model of multihop MP-eBGP peering is mainly used in the case of load balancing between multiple …

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Option 1(10A): Back-to-Back VRF – Inter-AS MPLS VPN – The whole story (2) – Updated Dec 2008

Well, lets start examining the different options that we have highlighted in the previous post one by one, in this post we shall be covering Option 10A (Type A as described in RFC 4364). The VRF-to-VRF (as stated in RFC 4364) or the back-to-back VRF (as named by Cisco) approach is the simplest method for allowing Inter-AS MPLS VPN between different providers. In this approach, PE routers residing in different autonomous systems function as ASBRs, interconnected via either a single link consisting of logical subinterfaces or via multiple physical links.

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L2VPN Pseudowire Redundancy (MPLS AToM Redundancy)

The MPLS L2VPN is growing exponentially,  back to the old days, customers were preferring FR and ATM VPN model due to the weakness of  Peer-to-Peer VPN model at this time, but after MPLS become fact on  the ground most of these customer migrated to MPLS L3VPN which solved all the Old Peer-To-Peer model issues, meanwhile the MPLS-L2VPN allows the service providers to provide different VPN models using the same network. Like other network applications L2VPN redundancy is desired for  services  delivery continuity, The L2VPN Pseudowire Redundancy feature allows edge routers to detect a failure in the network and reroute the …

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