Setup Guide

Configuring a basic BGP network
Configuring a basic BGP network includes a few mandatory tasks and many optional tasks. The initial step is to configure a BGP
routing and BGP peers, using the address family configuration. You can also configure BGP peers using the IPv4 VRF address
family.
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. Enable 4-Byte support for the BGP process.
CONFIG-ROUTER-BGP mode
bgp four-octet-as-support
NOTE:
This command is OPTIONAL. Use it only if you support 4-Byte AS numbers or if you support AS4 number
representation. Disable 4-Byte support and return to the default 2-Byte format by using the no bgp four-octet-
as-support command. You cannot disable 4-Byte support if you currently have a 4-Byte ASN configured.
3. Add a neighbor as a remote AS.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group name} remote-as as-number
Border Gateway Protocol (BGP)
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