Administrator Guide

Basic BGP configuration tasks
The following sections describe how to configure a basic BGP network and the basic configuration tasks that are required for
the BGP to be up and running.
Following are the basic configuration tasks required for BGP:
● Enabling BGP
● Configuring the router ID
● Configuring local AS number
● Configuring AS4 number representation
● Configuring a BGP peer
● Configuring a BGP peer group
Prerequisite for configuring a BGP network
You should be familiar with the overview of BGP before proceeding with configuring a basic BGP network. For more information
about the BGP overview, see Border Gateway Protocol IPv4 (BGPv4) Overview.
Restrictions
Dell EMC Networking OS supports only one BGP routing configuration and autonomous system (AS), but supports multiple
address family configuration.
Enabling BGP
By default, BGP is disabled on the system. Dell EMC Networking OS supports one autonomous system (AS) and assigns the
AS number (ASN). To enable the BGP process and begin exchanging information, assign an AS number and use commands in
ROUTER BGP mode to configure a BGP neighbor.
To establish BGP sessions and route traffic, configure at least one BGP neighbor or peer.
In BGP, routers with an established TCP connection are called neighbors or peers. After a connection is established, the
neighbors exchange full BGP routing tables with incremental updates afterward. In addition, neighbors exchange KEEPALIVE
messages to maintain the connection.
In BGP, neighbor routers or peers can be classified as internal or external. External BGP peers must be connected physically
to one another (unless you enable the EBGP multihop feature), while internal BGP peers do not need to be directly connected.
The IP address of an EBGP neighbor is usually the IP address of the interface directly connected to the router. First, the BGP
process determines if all internal BGP peers are reachable, then it determines which peers outside the AS are reachable.
Following is the sample configuration steps to enable BGP, configure a BGP router-id and network for a router. The same
configurations have to be repeated with appropriate changes in the IP addresses for a peer or router to achieve BGP session
between two devices. In the below configuration example, no address family is configured. So, the routing information for the
IPv4 unicast address family is advertised by default.
1. Assign an AS number and enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
● as-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte) or 0.1 to 65535.65535 (Dotted format).
Only one AS is supported per system.
NOTE: If you enter a 4-Byte AS number, 4-Byte AS support is enabled automatically.
2. Add a BGP neighbor or peer and AS number.
CONFIG-ROUTER-BGP mode
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Border Gateway Protocol (BGP)