Allied Telesis IPV6 manual Summary, Graceful restart for dynamic routing protocols

Graceful restart for dynamic routing protocols

Along with VCStack, the other key component of this IPv6 high availability solution is the implementation of graceful restart (also known as non-stop forwarding) within IPv6 dynamic routing protocols. Graceful restart is a feature that has been added to routing protocols (RIP, OSPF, BGP) in recent years. It enables Layer 3 routing to continue uninterrupted even while one of the routers in the network is, for a brief period, not participating in the routing protocol that is used to populate the routers’ route tables.

In normal circumstances, when routers detect that a neighbor is no longer participating in the routing protocol, they discard routes learnt from that neighbor. With graceful restart, the router that is going to briefly drop out of the protocol can inform its neighbors of its intention, and request that they continue to operate as though it was still participating.

Combining VCStack and graceful restart allows achievement of true Layer 3 router resiliency. VCStack enables multiple Layer 3 switches to operate together as one, and graceful restart keeps data flowing if the master switch of the VCStack is lost and the stack briefly drops out of a routing protocol while a new master takes over.

Combining that with graceful restart within the routing protocols provides a solution that can enable a Layer 3 switched IPv6 network to hitlessly recover from link loss, and recover from the loss of a stack member in very few seconds.

Summary

The standard Internet protocol of the future is IPv6. In the coming years, a great deal of time and effort will be expended in the process of transferring data communication systems from IPv4 to IPv6. The simpler this process is made for people, the more smoothly it will progress, and the less it will cost.

By providing a resilient Layer 3 switching solution, at an affordable price, that enables IPv4 and IPv6 to work in parallel with equal reliability and performance, Allied Telesis is able to help smooth the transition, as shown in diagram 3.

Full support for IPv6 transition technologies and resilient network products and protocols ensure that Allied Telesis switching technology provides a solution that is easy to manage, scalable and future-proof.

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Diagram 3 - IPv4 and IPv6 dynamic routing in parallel via a VCStack Layer 3 switch

High Availability IPv6 7