Solved: EBGP over IBGP

rajivrajan1 · ‎03-09-2007

We have two client locations which are connected to service provider network and interconnected too by vpn link.

We are running ibgp from loc -1 to service provider.

Static route from loc 2 to service provider.

WE want to run ebgp and (load balancing between two locations).Why ebgp is preffered over Ibgp pls help.

Danilo Dy · ‎03-10-2007

It depends.

Take note that all router running iBGP in the same AS domain should be fully meshed, else use Route Reflector.

It takes more what information you have given me so far to decide whether eBGP or iBGP is appropriate to you.

But since your Service Provider is involve in the iBGP, I rather you have eBGP than iBGP because whatever your Service Provider do in their BGP domain will affect you directly. Using eBGP, you provide more protection to your AS domain.

Attached is clear picture of what I have recommend above.

View solution in original post

devang_etcom · ‎03-09-2007

will you please explain it in more detail?

or if you can post the topology then it will be more easy to explaine...

regards

Devang

rajivrajan1 · ‎03-09-2007

pls go through the diagram.

I can not do anything with central location and service provider.

But i want to configure EBGP between Central and location 1 as well as Location 2 and Service provider.

I am feeling some inconsistence with IBGP between central and location 1.

Now Location 2 has to be connected to service provider with EBGP.So we are about to do this in a single shot i.e Ibgp between Location 1 and 2 for load balancing. If location 2 - central fails load to be rerouted through location 2.the same for location 2 also.

Is my plan Ok or can i go ahead with IBGP itself.

please suggest.

if EBGP implementation takes place any standars to be followed? pl guide.

Danilo Dy · ‎03-09-2007

Looking at your diagram, this is my recommendation;

1. eBGP between Central and Service Provider

2. iBGP between Central and Location-1. Central is Route Reflector while Location-1 is Route Reflector Client

3. eBGP between Location-2 and Service Provider.

4. iBGP between Location-2 and Location-1. Location-2 is Route Reflector while Location-1 is Route Reflector Client

5. GRE Tunnel between Central and Location-2

6. iBGP between Central and Location-2

devang_etcom · ‎03-09-2007

hi,

now your explaination creat some confusion... how your central location and location 2 is connected... there is EBGP between the ISP and location2 right!!!

and you are treating like central location is having two like... one link is centaral and location 2 via ISP and other is location 1 to location 2... and you want to use location 1 and location 2 as back up link... am i right...

regards

Devang

Danilo Dy · ‎03-09-2007

What I don't understand is how you able to run iBGP with your service provider, it should be eBGP.

eBGP is always preferred over iBGP because they have lower AD. iBGP has an AD of 200 while eBGP has an AD of 20.

http://www.cisco.com/warp/public/105/admin_distance.html

rajivrajan1 · ‎03-09-2007

let me explain once again clearly.

Current config set up.

1.Central location is connected to ISP by IBGP.

2.Location-1 is connected to Central location with IBGP.

my primary motive is not to connect to central location rather connect to ISP only.

Requirement.

1.Now Im about to connect Location-2 to ISP with EBGP.(Mandatory).

2.Meanwhile Im about to connect Location 1 with Central location with EBGP, which is connected to central location with ibgp already.(Optional)

3.And to implement IBGP between Location 1 and 2(Reason : Load Balancing between Location-1 and Location-2 as i told you in the previos mail.)

Restriction : I can not do anything with the IBGP which is configured between Central location and service provider.

now pls suggest ... that can i go ahead by changing the ibgp between Central and location 1 for this scenario.. will this work properly?

and Can load balancing acheived with out any issues?

Danilo Dy · ‎03-10-2007

It can be done if Central is using Service Provider AS and IP Address while Location-1 and Location-2 use their own AS and IP Address. It can be done also if Location-1 and Location-2 is using Private AS and IP Address from the same Service Provider.

Here's a second recommendation

1. You can retain iBGP between Central and Service Provider. That means Central is using Service Provider AS and IP Address.

2. Location-1 will eBGP with Central and Location-2 will eBGP with Service Provider. That means Location-1 and Location-2 have their own AS and IP Address or using Private AS and IP Address from the same Service Provider

3. Location-1 and Location-2 will run iBGP

Question now is what thus Cisco 3660 doing between Central and Location-1?

rajivrajan1 · ‎03-10-2007

Medan,

The real topoly is hard to bring in picture.More over These central and other locations are data centers.

One of the customer in location-1 data center

is connected through 3660 (EBGP)

hope u got it.

Danilo Dy · ‎03-10-2007

Ok, I stick to your question then. Thus my second recommendation meet your requirement?

rajivrajan1 · ‎03-10-2007

yeah, design is ok.

one more clarification required.

Which would be the more appropriate?

connecting Loc1- Central and Loc2-ISP using ibgp or EBGP.IF im going for IBGP the whole cloud would be in ibgp but what if a customer is in need of EBGP who connects loc 1 or 2?

My pals openion differs.

Im still in a dilemma.

pls suggest.

devang_etcom · ‎03-10-2007

so finally you want to reach at central location right...

normally user who are connected with the location 1 and location 2 should reach the central location... and if location2 and ISP link goes down then you want your traffice to follow the location1 link... and same for location1-central link fail over...

am i right???

regards

Devang

Danilo Dy · ‎03-10-2007

It depends.

Take note that all router running iBGP in the same AS domain should be fully meshed, else use Route Reflector.

It takes more what information you have given me so far to decide whether eBGP or iBGP is appropriate to you.

But since your Service Provider is involve in the iBGP, I rather you have eBGP than iBGP because whatever your Service Provider do in their BGP domain will affect you directly. Using eBGP, you provide more protection to your AS domain.

Attached is clear picture of what I have recommend above.

rajivrajan1 · ‎03-10-2007

great I was looking for this answer.

Why i am going for EBGP? ;)

Thanx a ton

Danilo Dy · ‎03-10-2007

No problem, thanks for the rate :)

Dandy