Solved eBGP CCNA 2018 lab question

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Trying to wrap my head around eBPG config as it is new to me. I've been through the practice lab provided a couple of times now and something still isn't clear.

The commands to configure the lab are as follows...
router bgp 65534
network 11.22.33.0 mask 255.255.255.192
neighbor 172.14.0.3 remote-as 64000
neighbor 172.14.0.3 local-as 32000
neighbor 172.14.0.3 prefix-list OUT out

The prefix-list commands excluded..

Can someone explain to be why there are three AS numbers listed? 65534, 64000, and 32000 ? I get that 64000 is the AS of the remote device you want to peer with, but why the 65534 and 32000 AS numbers for the local device?

Toward the end of the lab they mention what the routing table would look like of the device peer at IP 172.14.0.3....
*> 11.22.33.0/26 172.14.0.2 0 0 32000 65534 i

-Adam

@Adam-Tyler,

router bgp 65534

This is the AS you want that router to represented

neighbor 172.14.0.3 remote-as 64000

This is the eBGP connection to 64000

neighbor 172.14.0.3 local-as 32000

This is how to get the remote router in 65534 see this neighbor as being in AS 32000. and prepend AS 32000 to all updates to AS 65534

@Ronnie-Wong said in eBGP CCNA 2018 lab question:

router bgp 65534

This is the AS you want that router to represented

---This is the AS I want the local router to represent? the router we are configuring?

neighbor 172.14.0.3 remote-as 64000

This is the eBGP connection to 64000

----This seems pretty straight forwards, it's the AS of the intended peer. Remote router that has TCP connectivity.

neighbor 172.14.0.3 local-as 32000

This is how to get the remote router in 65534 see this neighbor as being in AS 32000. and prepend AS 32000 to all updates to AS 65534

----I'm afraid I don't follow here at all, "this is how to get the remote router in 65534 to see this neighbor"? Why is it the remote router? Isn't the remote AS 64000? Is 65534 just a process id or something? Doesn't matter?

-Adam

Wait, I think I may have found what I needed using info from this link..
https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13761-39.html

So really the "local-as" command appears to be optional and is only used to override the As originally specified? Does that about sum it up? Any particular reason they chose to use this command in the CCNA lab? Just to expose us to it?

-Adam

@Adam-Tyler said in eBGP CCNA 2018 lab question:

----I'm afraid I don't follow here at all, "this is how to get the remote router in 65534 to see this neighbor"? Why is it the remote router? Isn't the remote AS 64000? Is 65534 just a process id or something? Doesn't matter?

It all matters provided the topology you're given to deal with. If you have a router in the same AS but you want it to report as a different AS. then the local-as will be used.

@Adam-Tyler,

I'm assuming there was a reason they chose to do it that way...it's more than likely a setup for another lab too.