Administrator Guide

• Enable 4-byte support for the BGP process.
CONFIG-ROUTER-BGP mode
bgp four-octect-as-support
NOTE: If you enter a 4-byte AS number, 4-byte AS support is enabled automatically. 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 congured.
Example conguration for enabling four-byte autonomous system numbers
DellEMC# configure terminal
DellEMC(conf)# router bgp 80000
DellEMC(conf-router_bgp)# bgp four-octet-as-support
DellEMC(conf-router_bgp)# neighbor 20.20.20.1 remote-as 200
DellEMC(conf-router_bgp)# neighbor 20.20.20.1 no shutdown
DellEMC(conf-router_bgp)#exit
To view BGP conguration, use the show running-config bgp command in EXEC Privilege mode.
The following example shows the show ip bgp summary command output (4–byte AS number displays).
R2#show ip bgp summary
BGP router identifier 1.1.1.1, local 80000
BGP local RIB : Routes to be Added 0, Replaced 0, Withdrawn 0
1 neighbor(s) using 40960 bytes of memory
Neighbor AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/Pfx
20.20.20.1 200 0 0 0 0 0 00:00:00 0
Changing a BGP router ID
BGP uses the congured router ID to identify the devices in the network.
By default, the router ID is the highest IP address of the Loopback interface. If no Loopback interfaces are congured, the highest IP
address of a physical interface on the router is used as the BGP router ID. To change the default BGP router ID, use the following
command.
• Change the BGP router ID of a BGP router
ROUTER BGP mode
bgp router-id ip-address
ip-address- IP address in dotted decimal format.
NOTE
: Do not specify an IP address which is used by another device as a router ID.
Peering sessions are reset when you change the router ID of a BGP router. Upon changing the router ID, the system automatically
restarts the BGP instance for the conguration to take eect.
Example of changing BGP router ID
DellEMC# configure terminal
DellEMC(conf)# router bgp 400
DellEMC(conf-router_bgp)# bgp router-id 1.1.1.1
Following is the sample output of show ip bgp ipv4 multicast summary command.
DellEMC# show ip bgp summary
BGP router identifier 1.1.1.1, local AS number 400
BGP local RIB : Routes to be Added 0, Replaced 0, Withdrawn 0
1 neighbor(s) using 8192 bytes of memory
Border Gateway Protocol (BGP)
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