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 5 Configuring Basic BGP
Licensing Requirements for Basic BGP
You can turn off the suppression feature by configuring the best-path algorithm to compare the router
IDs. See the “Tuning the Best-Path Algorithm” section on page 6-9 for more information. If you
configure this feature, the new best path is always preferred to the existing one.
You cannot suppress the best-path change if any of the following conditions occur:
• The existing best path is no longer valid.
• 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.
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 Virtualization
BGP supports Virtual Routing and Forwarding instances (VRFs). By default, Cisco NX-OS places you
in the default VRF unless you specifically configure another VRF. For more information, see
Chapter 11, “Configuring Layer 3 Virtualization.”
Licensing Requirements for Basic BGP
The following table shows the licensing requirements for this feature:
Prerequisites for BGP
BGP has the following prerequisites:
Product License Requirement
Cisco NX-OS BGP requires a LAN Enterprise Services license. For a complete explanation of the Cisco NX-OS licensing
scheme and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide.
Note Make sure the LAN Base Services license is installed on the switch to enable Layer 3 interfaces.