[c-nsp] BGP next hops in BGP not in IGP

[Dino Sosic]

This is normal,

BGP does not install the route into the table unless the next-hop is reachable ( meaning installed in the RIB). How it is installed in the RIB: IGP, BGP, Connected, Static is irrelevant, as long as it exists in the RIB when the BGP scanner goes through its table. 

Cheers
Dino

-----Original Message-----

Message: 2
Date: Mon, 1 Aug 2016 10:36:00 +1000
From: Kamal Dissanayaka <kamalasiri at gmail.com>
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] BGP next hops in BGP not in IGP
Message-ID:
	<CAL1UUpVbfVtgePghe8f=ZACi_GQAtL1PbNa5taeNFQo18EDD8g at mail.gmail.com>
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HI All,

As my knowledge, BGP next hop needs to be in IGP in order to get BGP routes in routing table.
It looks like, it may have changed ?  BGP routes populate in routing table when the next-hp route is learned through BGP.

I tried some googling but I cannot get definite answer.

here is the scenrio

Router A (18162) 172.18.112.41---- 172.18.112.40 Router B (65001)
172.18.112.37 --- 172.18.112.38 Router C (65001)

On router C,

Subnet 172.18.112.40/30  is learned through IBGP, As far as I remeber on my old school this subnet should be learned through IGP to work properly.

Router C# sh ip route  172.18.112.41
Routing entry for 172.18.112.40/30
  Known via "bgp 65001", distance 200, metric 0, type internal
  Last update from 172.18.112.37 3w3d ago
  Routing Descriptor Blocks:
  * 172.18.112.37, from 172.18.112.37, 3w3d ago
      Route metric is 0, traffic share count is 1
      AS Hops 0

However other routes advertised from Router A is on routing table of Router C. Is it something expected ??
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