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Routing & Design Query

In our client Datacenter we have an infra setup as defined in the below concept.


LAN-Router(Redundant Mode)-6509


LAN Internet Seg Router (L3) Switch - 3550- Gonna replaced by 3750(Redundant Mode)--> Internet Screening Router(Internet Facing- (Reduntant)-3800 Series


Internet Access ( Under this segment Internet Oriented Setups are there)-HA-3500 Switch


(X) (Y) (Z) --> Multiple infra which is based on the ineternet.

We are in a position to replace the LAN Internet Segment router (3550 L3 Switch Gig model) Customer is challenging us to perform the replacement with 3750 without any major outage. Customer agrees for intermittent interupption of services.

IBGP is running between LAN Internet segment routers A & B and Ebgp running between LAN end routers & Internet routers.

I personally feel its technically possible. But am worrying about taking the challenge considering the flaws in performing this.

My plan is like this Putting the existing LAN Internet Seg router B down & bring the new 3750 new switch and establish the EBGP alone to take the traffic.

If that recieves and transmits the traffic I will go ahead and power down the router A and replace with the 3750 by againestablishing the EBGP alone. if both does well then i will establish the IBGP between the routers.

Traffic towards LAN will be taken care by LAN router & Internet will taken care by the screening router. IBGP will have the same routes exhanging between the two LAN inetrenet segment routers.

Do we have any challenge in replacing the different hardware. Does it makes any flaws in the routing. while doing as per my plan.


Routing & Design Query

Guys, Please help me out if anyone has an idea about this.

Community Member

Routing & Design Query

Hi Mate...

Lets see if i can help you on this..

First,  I assume we have 2 x 6509, 2x 3550 and 2 routers facing the internet, correct ?

Between the lan we have IBGP and EBGP with the internet, correct ?  WHich IGP we have between the 3550`s and the 6509 devices ?

Your chalenge here is to replace the 3550`s with 3750 while costumer continue to work without any makor outages, correct ?

DO you have a good topology for this environment ?

talk to you soon !

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