Cisco Nexus 7000 Series - Guidelines and Limitations for BGP; CLI Configuration Modes; Global Configuration Mode

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10-8
Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
OL-20002-02
Chapter 10 Configuring Basic BGP
Guidelines and Limitations for BGP
• You must have an AS number, either assigned by a Regional Internet Registry (RIR) or locally
administered.
• You must configure at least one IGP that is capable of recursive next-hop resolution.
• You must configure an address family under a neighbor for the BGP session establishment.
Guidelines and Limitations for BGP
Use the following guidelines and limitations to configure BGP:
• The dynamic AS number prefix peer configuration the overrides individual AS number
configuration inherited from a BGP template.
• If you configure a dynamic AS number for prefix peers in an AS confederation, BGP establishes
sessions with only the AS numbers in the local confederation.
• BGP sessions created through a dynamic AS number prefix peer ignore any configured eBGP
multihop time-to-live (TTL) value or a disabled check for directly connected peers.
• Configure a router ID for BGP to avoid automatic router ID changes and session flaps.
• Use the maximum-prefix configuration option per peer to restrict the number of routes received and
system resources used.
• Configure the update-source to establish a session with BGP/eBGP multihop sessions.
• Specify a BGP policy if you configure redistribution.
• Define the BGP router ID within a VRF.
• If you decrease the keepalive and hold timer values, you might experience BGP session flaps.
• If you configure VDCs, install the Advanced Services license and enter the desired VDC (see to the
Cisco NX-OS Virtual Device Context Configuration Guide).
• If you configure VRFs, install the Advanced Services license and enter the desired VRF (see
Chapter 14, “Configuring Layer 3 Virtualization”).
CLI Configuration Modes
The following sections describe how to enter each of the CLI configuration modes for BGP. From a
mode, you can enter the ? command to display the commands available in that mode.
Global Configuration Mode
Use global configuration mode to create a BGP process and configure advanced features such as AS
confederation and route dampening. For more information, see Chapter 11, “Configuring Advanced
BGP.”
The following example shows how to enter router configuration mode:
switch# configuration
switch(config)# router bgp 64496
switch(config-router)#