BGP routing table entry for /16, version Paths: (4 available, best #1) Advertised to peer-groups: AS4544-AGG-CUSTOMER-FULL from ( ) Origin IGP, metric 90, localpref 70, valid, external, best Community: 4544: , (received-only) from ( )...

[AS 3549] 0 msec [AS 3549] 24 msec 3 sjp-brdr-01.inet.qwest.net ( ) [AS 209] 24 msec 4 svx-core-01.inet.qwest.net ( ) [AS 209] 28 msec 5 svl-core-02.inet.qwest.net ( ) [AS 209] 28 msec [AS 209] 64 msec [AS 209] 72 msecc [AS 2553] 72 msec [AS 2553] 76 msec

ORL AS 100 TLH AS 200 MIA AS 400 TPA AS

R1-ORL router bgp 100 neighbor remote-as 200 neighbor remote-as 400 network mask network mask network mask network mask

R2-TLH router bgp 200 neighbor remote-as 100 neighbor remote-as 300 network mask network mask network mask

R3-TPA router bgp 300 neighbor remote-as 200 neighbor remote-as 400 network mask network mask network mask

R4-MIA router bgp 400 neighbor remote-as 100 neighbor remote-as 300 network mask network mask

clear ip bgp * reset all my bgp peer connections probably don’t want to reset all in production network :) clear ip bgp N (where N is AS #) clear ip bgp A.B.C.D (neighbor’s IP)

R2-TLH# sh ip bgp summary BGP router identifier , local AS number 200 BGP table version is 17, main routing table version network entries and 21 paths using 1920 bytes of memory 7 BGP path attribute entries using 420 bytes of memory 6 BGP AS-PATH entries using 144 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP activity 15/9 prefixes, 24/3 paths, scan interval 60 secs Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd :26: :26:22 9

R2-TLH# sh ip bgp summary.... Neighbor V AS MsgRcvd MsgSent TblVer

R2-TLH# sh ip bgp BGP routing table entry for /24, version 10 Paths: (2 available, best #2, table Default-IP-Routing-Table) Advertised to non peer-group peers: from ( ) Origin IGP, localpref 100, valid, external from ( ) Origin IGP, metric 0, localpref 100, valid, external, best R2-TLH#

R2-TLH#sh ip bgp BGP table version is 41, local router ID is Status codes: s suppressed,... Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop... Path *> i * i *> i * i *> i * i *> i *> i * i

R2-TLH# sh ip bgp regexp BGP table version is 17, local router ID is Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * i * i * i * i * i

R2-TLH# sh ip bgp regexp ^ $ BGP table version is 17, local router ID is Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * i * i

config commands to restrict announcement access-list 1 deny access-list 1 permit router bgp 200 neighbor distribute-list 1 out

(ROUTE NOT ADVERTISED to ) R2-TLH# sh ip bgp BGP routing table entry for /24, version 3 Paths: (1 available, best #1, table Default-IP-Routing-Table) Advertised to non peer-group peers: Local from ( ) Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced, local, best

(ROUTE STILL KNOWN VIA ALTERNATE PATH) R1-ORL# sh ip bgp BGP routing table entry for /24, version 18 Paths: (1 available, best #1) Advertised to non peer-group peers: from ( ) Origin IGP, localpref 100, valid, external, best, ref 2

Filtering based on AS_PATH quick way to make sure you are not a transit AS ip as-path access-list 2 permit ^$ advertise only routes this AS originates neighbor A.B.C.D filter-list 2 out (for all neighbors) you still have full routes from all peers

R2-TLH#sh ip bgp nei routes BGP table version is 25, local router ID is Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> i * i * i *> i *> i *> i * i * i * i Total number of prefixes 9

R2-TLH#sh ip bgp nei routes BGP table version is 33, local router ID is Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> i *> i *> i *> i Total number of prefixes 4