Specifications

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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, Release 5.0(3)U2(2)
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Chapter 6 Configuring Advanced BGP
Information About Advanced BGP
• Next hop becomes a nonlocal address.
Note Reachability and recursed metric events trigger a best-path recalculation.
Event notifications from the RIB are classified as critical and noncritical. Notifications for critical and
noncritical events are sent in separate batches. However, a noncritical event is sent with the critical
events if the noncritical event is pending and there is a request to read the critical events.
• Critical events are related to the reachability (reachable and unreachable), connectivity (connected
and unconnected), and locality (local and nonlocal) of the next hops. Notifications for these events
are not delayed.
• Noncritical events include only the IGP metric changes.
See the “Configuring BGP Next-Hop Address Tracking” section on page 6-21 for more information.
Route Redistribution
You can configure BGP to redistribute static routes or routes from other protocols. You configure a route
policy with the redistribution to control which routes are passed into BGP. A route policy allows you to
filter routes based on attributes such as the destination, origination protocol, route type, route tag, and
so on. See Chapter 13, “Configuring Route Policy Manager,” for more information.
BFD
This feature supports bidirectional forwarding detection (BFD). BFD is a detection protocol designed to
provide fast forwarding-path failure detection times. BFD provides subsecond failure detection between
two adjacent devices and can be less CPU-intensive than protocol hello messages because some of the
BFD load can be distributed onto the data plane on supported modules.
BFD for BGP is supported on eBGP single-hop peers and iBGP single-hop peers. For iBGP single-hop
peers using BFD, you must configure the update-source option in neighbor configuration mode. BFD is
not supported on other iBGP peers or for multihop eBGP peers.
BFD is supported for the following types of interfaces:
• L3 physical and subinterface
• L3 port-channel and subinterface
• SVI
BFD for BGP does not support authentication or per-link BFD sessions on a port-channel.
See Chapter 7, “Configuring Bidirectional Forwarding Detection for BGP” for more information.
Tuning BGP
You can modify the default behavior of BGP through BGP timers and by adjusting the best-path
algorithm.
This section includes the following topics:
• BGP Timers, page 6-9
• Tuning the Best-Path Algorithm, page 6-9