Understanding How Graceful Restart Enables Uninterrupted Packet Forwarding When A Router Is Restarted; Graceful Restart Concepts - Juniper EX9200 Features Manual

CHAPTER 10
Understanding How Graceful Restart
Enables Uninterrupted Packet Forwarding
When a Router Is Restarted

Graceful Restart Concepts

Copyright © 2017, Juniper Networks, Inc.
Graceful Restart Concepts on page 65
Graceful Restart for Aggregate and Static Routes on page 66
Graceful Restart and Routing Protocols on page 66
Graceful Restart and MPLS-Related Protocols on page 69
Graceful Restart and Layer 2 and Layer 3 VPNs on page 70
Graceful Restart on Logical Systems on page 71
With routing protocols, any service interruption requires that an affected router recalculate
adjacencies with neighboring routers, restore routing table entries, and update other
protocol-specific information. An unprotected restart of a router can result in forwarding
delays, route flapping, wait times stemming from protocol reconvergence, and even
dropped packets. The main benefits of graceful restart are uninterrupted packet
forwarding and temporary suppression of all routing protocol updates. Graceful restart
enables a router to pass through intermediate convergence states that are hidden from
the rest of the network.
Three main types of graceful restart are available on Juniper Networks routing platforms:
Graceful restart for aggregate and static routes and for routing protocols—Provides
protection for aggregate and static routes and for Border Gateway Protocol (BGP),
End System-to-Intermediate System (ES-IS), Intermediate System-to-Intermediate
System (IS-IS), Open Shortest Path First (OSPF), Routing Information Protocol (RIP),
next-generation RIP (RIPng), and Protocol Independent Multicast (PIM) sparse mode
routing protocols.
Graceful restart for MPLS-related protocols—Provides protection for Label Distribution
Protocol (LDP), Resource Reservation Protocol (RSVP), circuit cross-connect (CCC),
and translational cross-connect (TCC). (Not supported on OCX Series switches.)
Graceful restart for virtual private networks (VPNs)—Provides protection for Layer 2
and Layer 3 VPNs.
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