Administrator Guide

Configuration Information
The software supports BGPv4 as well as the following:
• deterministic multi-exit discriminator (MED) (default)
• a path with a missing MED is treated as worst path and assigned an MED value of (0xffffffff)
• the community format follows RFC 1998
• delayed configuration (the software at system boot reads the entire configuration file prior to sending messages to start BGP peer
sessions)
The following are not yet supported:
• auto-summarization (the default is no auto-summary)
• synchronization (the default is no synchronization)
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.
Border Gateway Protocol (BGP)
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