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BGP.is it mandatory to do clear ip bgp after adding new network

webstd.design
Level 1
Level 1

Hi,

<RouterID 10.10.10.1>----eBGP----<RouterID 10.10.1.1>---adding new subnet 10.10.1.2

In case if we add new subnet like 10.10.1.2 into bgp using network command should we do clear ip bgp x.x.x.x?

Thanks


1 Accepted Solution

Accepted Solutions

Hi,

if you modify a policy then you must do either a soft reset or a route-refresh( with clear ip bgp x.x.x.x in or clear ip bgp x.x.x.x out).

Regards.

Alain

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View solution in original post

8 Replies 8

Hi,

   No need. Just make sure that the new "network" you added is already in RIB.

HTH,

Toshi

cadet alain
VIP Alumni
VIP Alumni

Hi,

no it isn't and as a side note as most routers support route refresh you should be better doing a clear ip bgp x.x.x.x in or

clear ip bgp x.x.x.x out which are soft resets which don't tear the peering.

Regards.

Alain.

Don't forget to rate helpful posts.

--10.10.10.2----eBGP----10.10.1.2-----adding new subnet 10.10.1.20/30

I'm not able to find subnetwork 10.10.1.20/30 with command below:

10.10.10.1> sh ip bgp neigh 10.10.1.2 routes

Also this command doesn't show route 10.10.1.20/30

10.10.1.1> sh ip bgp neigh 10.10.1.2 advertised-routes

Can see 10.10.1.20/30 in below

10.10.1.1>sh ip bgp

Can't see 10.10.1.20/30 in below

10.10.10.1>sh ip bgp

What should I within clear ip bgp? or any other usefull command? Any glue?

Thanks

clear ip bgp is not mandatory the only the important thing is the mask in the network statment and in the routing table should be same.

syed.

Hi,

aren't you filtering the prefixes advertised to  10.10.1.2?

Outgoing route-map, filter-list, etc.?

You could try

clear ip bgp 10.10.1.2 soft

but it should not be necessary if the  10.10.1.20/30 was in the RIB at the moment you added

network 10.10.1.20 mask 255.255.255.252

to you BGP config.

Another low probability  chance:

Aren't you receiving the same prefix from 10.10.1.2 already with better BGP attributes?

In that way you would not advertise  the prefix back.

Or isn't the prefix next-hop pointing to 10.10.1.2?

HTH,

Milan

10.10.1.20 is directly connected network on RouterID 10.10.1.1

I don't think that I should add this route into IGP, as we use eBGP between RouterID 10.10.1.1 and RouterID 10.10.10.1

If we modify policy - should we do clear ip bgp soft?

Hi,

if you modify a policy then you must do either a soft reset or a route-refresh( with clear ip bgp x.x.x.x in or clear ip bgp x.x.x.x out).

Regards.

Alain

Don't forget to rate helpful posts.
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