Bgp And The Unicast Rib; Bgp Virtualization; Licensing Requirements For Basic Bgp; Prerequisites For Bgp - Cisco Nexus 7000 Series Configuration Manual

Chapter 10 Configuring Basic BGP
S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m .
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BGP and the Unicast RIB

BGP communicates with the unicast routing information base (unicast RIB) to store IPv4 routes in the
unicast routing table. After selecting the best path, if BGP determines that the best path change needs to
be reflected in the routing table, it sends a route update to the unicast RIB.
BGP receives route notifications regarding changes to its routes in the unicast RIB. It also receives route
notifications about other protocol routes to support redistribution.
BGP also receives notifications from the unicast RIB regarding next-hop changes. BGP uses these
notifications to keep track of the reachability and IGP metric to the next-hop addresses.
Whenever the next-hop reachability or IGP metrics in the unicast RIB change, BGP triggers a best-path
recalculation for affected routes.
BGP communicates with the IPv6 unicast RIB to perform these operations for IPv6 routes.

BGP Virtualization

BGP supports Virtual Routing and Forwarding instances (VRFs). VRFs exist within virtual device
contexts (VDCs). By default, Cisco NX-OS places you in the default VDC and default VRF unless you
specifically configure another VDC and VRF. For more information, see the Cisco Nexus 7000 Series
NX-OS Virtual Device Context Configuration Guide, Release 4.x and
Virtualization."

Licensing Requirements for Basic BGP

The following table shows the licensing requirements for this feature:
Product License Requirement
NX-OS BGP requires an Enterprise Services license. For a complete explanation of the NX-OS licensing scheme
and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide.

Prerequisites for BGP

BGP has the following prerequisites:
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Either the existing or new best paths were received from internal (or confederation) peers or were
locally generated (for example, by redistribution).
The paths were received from the same peer (the paths have the same router ID).
The paths have different weights, local preferences, origins, or IGP metrics to their next-hop
addresses.
The paths have different MEDs.
You must enable the BGP feature (see the
You should have a valid router ID configured on the system.
Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
Licensing Requirements for Basic BGP
Chapter 14, "Configuring Layer 3
"Enabling the BGP Feature" section on page 10-10).
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