The conversation with Hussein is very good conversation but its a bit muddled.
I think basically an example was used that was kind of special case to demonstrate perhaps some commands and partial thought process.
I also wondered about the disabled connected and the reason I wondered about the disabled connected check was that I did not think the loop back was seen as directly connected because I didn’t think the loopback was seen.
The reason I didn’t think the loopback was seen was because it counted the loopback as a hop (is that wrong word?) meaning it incremented the TTL by 1 which added up to a total of 2. so I thought once you fixed that then it could show up if you had the following commands required by BGP which I thought was the following:
R1(config)#router bgp 1
R1(config-router)#neighbor 2.2.2.2 remote-as 2
R1(config-router)#neighbor 2.2.2.2 update-source loopback 0
R1(config-router)#neighbor 2.2.2.2 ebgp-multihop 2
So to me using the disabled connected command was meaningless in regards to that. I think you was trying to point out something by using it but I don’t know what it was you was trying to get at. You finally said it was not needed and that makes sense to me in how I understand how things work. In addition, it was just where you was going with it in the first place that was not clear to me.
hope that’s clear but its hard to communicate some of these advanced granular thing as you know because even harder to try and write the lessons to convey these things I am sure.
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Next question:
Right now I am thinking BGP unlike IGP routing protocols and also unlike static routes does not supply connectivity. Let me give some examples hopefully they help communicate my thought process.
the reason BGP works on directly connected routers is only because directly connected routes show up in the routing table minus loop back which as mentioned above has a TTL issue that has to be modified and then you can add as neighbor.
So in some ways using directly connected routers does not pound in the issue of the truth as I believe it. you have to have routes in place to run BGP over or it has to be directly connected otherwise they don’t know where to send crap because they don’t know the road to where they need to go.
This is confusing because every other thing you setup when you set it up that is the road but not with BGP as I understand it. So if not directly connected you need either a routing protocol or static routes to provide a road for BGP to run over.
Is that connect thinking? Its not really stated explicitly anywhere in the reading and perhaps because its not easy to state that in a few words as I just drummed on for half a page trying to ask the question.
If I had to sum up everything I just said in a few words it would be the following and I will quote myself(can people quote themselves?? lol)
BGP will only run over directly connected links or run over additional routing protocol or static route. In a very broad and loose sense it works a bit like a VPN running over something else, or as OSPF running over frame replay. It has to has to know where its going! BGP by itself does not provide itself a road map over Ethernet as do other IGP and static routes.
even that is not great wording because BGP runs but does not provide end to end connectivity for things to get from point A to point B.
If I used an analogy I would say:
BGP is like driving your car on a highway without any road signs or directions you simply don’t know how to get where you need to. You must use GPS(a routing protocol ) or they have to put in road signs (static routes). Once that’s done you can get to where you need to go and also know how to get back home where you started.
could add the reason you don’t need routing protocols or static routes for directly connected is basically same principle:
if you can see the store from your house you don’t need maps because you can see all the information right there both to reach it and to return from it.
I didn’t mention it my main assertions as I figured most at this level probably understood that.
Is my thinking correct on this?
), What I mean is, neighbour relationships are configured manually, and neighbours don’t have to be physically adjacent. This means that routing must be established in some form or another (static route, IGP) between the BGP neighbouring routers in order for them to exchange BGP routing information. One might say “well if we have to run an IGP to get BGP to function, what’s the point?” I stress that routing between the two routers must be established for the exchange of BGP routing information, and NOT for the transfer of user data. Once BGP neighbourhoodship has been established, BGP routes can be exchanged and the network can converge for the purpose of transferring user data.