Dell S4820T, Configuration Manual

Page: 228 / 1178

router bgp 65123
bgp router-id 192.168.10.2
network 10.10.21.0/24
network 10.10.32.0/24
network 100.10.92.0/24
network 192.168.10.0/24
bgp four-octet-as-support
neighbor 10.10.21.1 remote-as 65123
neighbor 10.10.21.1 filter-list Laura in
neighbor 10.10.21.1 no shutdown
neighbor 10.10.32.3 remote-as 65123
neighbor 10.10.32.3 no shutdown
neighbor 100.10.92.9 remote-as 65192
neighbor 100.10.92.9 local-as 6500
neighbor 100.10.92.9 no shutdown
neighbor 192.168.10.1 remote-as 65123
neighbor 192.168.10.1 update-source Loopback 0
neighbor 192.168.10.1 no shutdown
neighbor 192.168.12.2 remote-as 65123
neighbor 192.168.12.2 update-source Loopback 0
neighbor 192.168.12.2 no shutdown
R2(conf-router_bgp)#
Allowing an AS Number to Appear in its Own AS Path
This command allows you to set the number of times a particular AS number can occur in the AS path.
The allow-as feature permits a BGP speaker to allow the ASN to be present for a specified number of
times in the update received from the peer, even if that ASN matches its own. The AS-PATH loop is
detected if the local ASN is present more than the specified number of times in the command.
• Allow this neighbor ID to use the AS path the specified number of times.
CONFIG-ROUTER-BGP mode
neighbor { IP address | peer-group-name } allowas-in number
–
Peer Group Name
: 16 characters.
–
Number
: 1 through 10.
Format: IP Address: A.B.C.D.
You must Configure Peer Groups before assigning it to an AS.
Example of Viewing AS Numbers in AS Paths
The lines shown in bold are the number of times ASN 65123 can appear in the AS path ( allows–in 9 ).
To disable this feature, use the
no neighbor allow-as in number
command in CONFIGURATION
ROUTER BGP mode.
R2(conf-router_bgp)#show conf
!
router bgp 65123
bgp router-id 192.168.10.2
network 10.10.21.0/24
network 10.10.32.0/24
network 100.10.92.0/24
network 192.168.10.0/24
bgp four-octet-as-support
neighbor 10.10.21.1 remote-as 65123
228
Border Gateway Protocol IPv4 (BGPv4)