Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 390)

NOTE
RIB-out peer grouping is not shared between different VRFs or address families.
Implementation of BGP4
BGP4 is described in RFC 1771 and the latest BGP4 drafts. The Brocade BGP4 implementation fully
complies with RFC 1771. Brocade BGP4 implementation also supports the following RFCs:
• RFC 1745 (OSPF Interactions)
• RFC 1997 (BGP Communities Attributes)
• RFC 2385 (TCP MD5 Signature Option)
• RFC 2439 (Route Flap Dampening)
• RFC 2796 (Route Reflection)
• RFC 2842 (Capability Advertisement)
• RFC 3065 (BGP4 Confederations)
• RFC 2858 (Multiprotocol Extensions)
• RFC 2918 (Route Refresh Capability)
• RFC 3392 (BGP4 Capability Advertisement)
• RFC 4893 BGP Support for Four-octet AS Number Space
• RFC 3682 Generalized TTL Security Mechanism, for eBGP Session Protection
BGP4 restart
BGP4 restart is a high-availability routing feature that minimizes disruption in traffic forwarding,
diminishes route flapping, and provides continuous service during a system restart, switchover,
failover, or hitless OS upgrade. During such events, routes remain available between devices. BGP4
restart operates between a device and its peers, and must be configured on each participating device.
Under normal operation, when a BGP4 device is restarted, the network is automatically reconfigured.
Routes available through the restarting device are deleted when the device goes down, and are then
rediscovered and added back to the routing tables when the device is back up and running. In a
network with devices that regularly restart, performance can degrade significantly and limit the
availability of network resources. BGP4 restart dampens the network response and limits route
flapping by allowing routes to remain available between devices during a restart. BGP4 restart
operates between a device and peers, and must be configured on each participating device.
BGP4 restart is enabled globally by default.
A BGP4 restart-enabled device advertises the capability to establish peering relationships with other
devices. When a restart begins, neighbor devices mark all of the routes from the restarting device as
stale, but continue to use the routes for the length of time specified by the restart timer. After the
device is restarted, it begins to receive routing updates from the peers. When it receives the end-of-
RIB marker that indicates it has received all of the BGP4 route updates, it recomputes the new routes
and replaces the stale routes in the route map with the newly computed routes. If the device does not
come back up within the time configured for the purge timer, the stale routes are removed.
Implementation of BGP4
390 FastIron Ethernet Switch Layer 3 Routing Configuration Guide
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