bgp table (i what is it mean )

[networkinblood]

HI team ,

In bgp table one i (origin code , prefix are generated by network command) and what is mean of other i(internal). ????

According to cisco it is internal but I tried to find out in varies documents but still I m very confused .

 My query might me silly , but your reply will help other guys too.

thnks in advance

[Martin L]

see attached pic From Routing TCP/IP book by Jeff Dolye, vol 2 and 2nd edition, CiscoPress 2017

[networkinblood]

hi

its really confusing as per attached file ...bgp local rib table must have only single path for each prefix (if bgp multipath is not configured ).......... but as I tested in lab bgp lacal rib table having all available path after applying policies to adj in rib table (like eigrp ).

.either output of lab is wrong or the statement in attached file is wrong 

pls find the out of lab

CSS2#sh ip bgp vpnv4 all
BGP table version is 4, local router ID is 2.2.2.2
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
Route Distinguisher: 1:1 (default for vrf BEARER)
* 11.11.11.11/32 172.12.1.2 0 10 10 10 10 ?
*>i                        1.1.1.1 0 100 0 10 ?
* i                         1.1.1.1 0 100 0 10 ?
*> 33.33.33.33/32 172.12.1.2 0 0 10 10 10 10 ?

[Martin L]

This is correct; what else would you want to see?  Show ip bgp shows all valid paths and selected best. Note that between 2 and more same prefixes, the oldest one is at the bottom while newer one on the top.  You can see valid and all available paths and make selection why was this particular one selected as Best.  If you would not see others (2nd best and so forth), you could not have make a policy to make one preferred over the other one.  you would have to check your neighbor and ask him to tell you what prefixes with what attributes he sends you.  If you only see one of 33.33.33.33/32 and one of 11.11.11.11/32 , you would not be able to make changes if you wish to make traffic manipulation, aka traffic engineering. 

Only best routes are passed over to Routing table (RIB). So, you have 2 useful tables with BGP, BGP local table and RIB with other protocols as well.   Similarly in EGIRP, you must use "show ip eigrp topology all-links" to see all available paths in contrast to only best one with "show ip eigrp topology ".

Regards, ML
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[networkinblood]

Thnks for revert and valuable discussion, now I m comfortable about bgp
local rib table.......


If I will face any problem , I will come again for discussion ...


And sorry if my any query was silly

[networkinblood]

Hi Sir ,

Once again thanks for your revert .

As you mentioned local rib table contains all available path for each
prefix ( same like eigrp topology table ) and than bgp best path selection
algorithm applied on local rib table .


Recieving best prefix from peer ----->>> forming Adj in table ------ >>
applying all inbound policies --------- >>forming local bgp rib table
---------- >>applying bgp best path selection algorithm ----->>>best path
get elected in bgp routing table ..--------->>>>>out bound policies
applied------>>>>forming bgp adj out table ..



Sir pls correct me if I am wrong any where.