• No Prepend: specifies that local AS values are not prepended to announcements from the neighbor.Format: IP Address: A.B.C.D.You must Configure Peer Groups before assigning it to an AS. This feature is not supported on passive peer groups.Example of the Verifying that Local AS Numbering is DisabledThe first line in bold shows the actual AS number. The second two lines in bold show the local AS number (6500) maintained duringmigration.To disable this feature, use the no neighbor local-as command in CONFIGURATION ROUTER BGP mode.R2(conf-router_bgp)#show conf!router bgp 65123bgp router-id 192.168.10.2network 10.10.21.0/24network 10.10.32.0/24network 100.10.92.0/24network 192.168.10.0/24bgp four-octet-as-supportneighbor 10.10.21.1 remote-as 65123neighbor 10.10.21.1 filter-list Laura inneighbor 10.10.21.1 no shutdownneighbor 10.10.32.3 remote-as 65123neighbor 10.10.32.3 no shutdownneighbor 100.10.92.9 remote-as 65192neighbor 100.10.92.9 local-as 6500neighbor 100.10.92.9 no shutdownneighbor 192.168.10.1 remote-as 65123neighbor 192.168.10.1 update-source Loopback 0neighbor 192.168.10.1 no shutdownneighbor 192.168.12.2 remote-as 65123neighbor 192.168.12.2 update-source Loopback 0neighbor 192.168.12.2 no shutdownR2(conf-router_bgp)#Allowing an AS Number to Appear in its Own AS PathThis 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 fromthe 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 oftimes in the command.• Allow this neighbor ID to use the AS path the specified number of times.CONFIG-ROUTER-BGP modeneighbor {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 PathsThe 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!Border Gateway Protocol IPv4 (BGPv4) 189
