BGP routes select issue

[gbcbooksmj]

please help me to explain why bgp choose 172.28.144.5 as the next jump for prefix 10.0.0.0/8

check my attachment

[Julio E. Moisa]

Hi 

Apologies for the late response

If you want to see more routes learned by BGP you could configure under the BGP the command:

bgp additional-paths install

:-)

[gbcbooksmj]

can you post a complete command .

honestly , i couldn't find match command line under router bgp view .

[Julio E. Moisa]

Sure my friend, the config should be, before to apply it on production devices try to test it on a lab. 

router bgp <AS>

address-family ipv4
bgp additional-paths install

[gbcbooksmj]

i did not see this command on my device or a lab 

BTW , did you know how to count number from BGR routes from specific AS

example , i want to know how many routes i have receive from as 65530

[gbcbooksmj]

any reply ? 

[Julio E. Moisa]

Hi

Try using this command line, to verify the routes learned and originated in AS 65530

sh ip bgp regexp ^65530$

:-)

[gbcbooksmj]

yes, it only print out all bgp route from 65530 

but no count number ...

[gbcbooksmj]

and , do you know how to count number bgp routes from explicit AS

for example 

i need to know how many bgp routes receive from peer 192.168.1.1

[gbcbooksmj]

and i actually confuse with this result

show bgp summary

show ip bgp summary

get different result

[Masoud Pourshabanian]

Show IP BGP shows the content of BGP table.

Show BGP also shows the content of BGP table for IP. BGP is multi protocols. It supports different protocols. IP is default.

clear IP BGP * or x.x.x.x is hard reset. it takes down the neighbor session.

clear IP BGP in uses route-refresh capability. By route refresh, BGP does not tear the BGP session down. It sends a message to the neighbor and requests for the updates.

clear IP BGP soft in is used with BGP soft configuration. When BGP soft configuration is configured, bgp keeps a copy of all received routes in a separate table. When you run clear ip bgp x.x.x.x soft in, BGP goes to that table applies the policy and the result will sit in in BGP table. (no neighbor request) but more memory)

[Masoud Pourshabanian]

Try this one

sh ip bgp regexp .+      (external)

sh ip bgp regexp  ^$   (locally generated)

[Julio E. Moisa]

Hi

The MED with lowest value is preferred, in this case 10 is preferred unless something else is applied to manipulate the traffic.

One of the duplicate entry shows (received-only) it means that the prefixes was received but not installed on the routing table. So something like a route-map is being applied to do a specific task. 

[Masoud Pourshabanian]

The reason for received-only is BGP soft configuration. When you activate soft configuration, BGP keeps two copies. One copy before applying the policies (received only) and other after applying the policies.

In your case, I would say it is just matter of time if you have not configured bgp best path compare-routerid. 

172.28.144.5 is the next jump for prefix 10.0.0.0/8 because it is oldest. You can see its life time by looking at routing table but not sure how to check the lifetime of the other route.

You can flap the neighbor for the best route at downtime to see the second route becomes the best or not.