Two first things that are considered the "BGP configuration best practice" are to disable the SYNCHRONIZATION and disable the Auto Summarization. Why?
Auto-summary - to enable the CLASSLESS BGP behavior
(config-router)#no auto-summary
Synchronization - it's an old loop prevention mechanism that is no longer used, so there is no need to have it enabled. In the newer versions of IOS it's disabled by default.
It was originally created to preven the BLACK HOLE Advertising. Basically the SYNC Logic is: Do not consider an iBGP route in the BGP table BEST unless the EXACT PREFIX was learned via IGP and is currently in the routing table.
R2(config-router)#no synchronization
*TIP: When using OSPF and BGP in the same Network - use the same Router ID due to the Sync Logic!
Once you've got the neighbors configured using the "neighbor" command, you should be able to identify the outputs:
(config-router)#do show ip bgp summary
BGP router identifier 192.168.2.2, local AS number 100
BGP table version is 5, main routing table version 5
4 network entries using 480 bytes of memory
4 path entries using 208 bytes of memory
2/2 BGP path/bestpath attribute entries using 248 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 using 936 total bytes of memory
BGP activity 4/0 prefixes, 4/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
100.11.1.1 4 100 9 9 5 0 0 00:05:23 1
100.11.1.3 4 100 9 9 5 0 0 00:05:12 1
100.11.1.4 4 100 8 8 5 0 0 00:04:57 1
(config-router)#do show ip bgp <--- ONLY iBGP in this case
BGP table version is 5, local router ID is 192.168.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i1.0.0.0 10.1.1.1 0 100 0 i
*> 2.0.0.0 0.0.0.0 0 32768 i
*>i3.0.0.0 10.1.1.3 0 100 0 i
*>i4.0.0.0 10.1.1.4 0 100 0 i
* - The entry in the table is valid
> - It's the BEST entry for that prefix
i - learned via iBGP
(config-router)#do show ip bgp <--- ONLY eBGP in this case
BGP table version is 5, local router ID is 192.168.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
* 1.0.0.0 10.1.1.1 0 300 100 i
* 10.1.1.1 0 200 100 i
*> 10.1.1.1 0 0 100 i
* 2.0.0.0 10.1.1.2 0 100 200 i
* 10.1.1.2 0 300 200 i
*> 10.1.1.2 0 0 200 i
*> 3.0.0.0 10.1.1.3 0 0 300 i
*> 4.0.0.0 0.0.0.0 0 32768 i
Notice that the PATH is no longer marked as "i" for iBGP, but it shows an entire AS-PATH now (list of all the BGP Autonomous Systems the route needs to pass in order to reach the route)
Also Local Preference is no longer marked as 100 (default for iBGP)
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