Solved: want to replace the existing router 1800 to layer 3 4503 switch in existing set-up

vinodjad1234 · ‎08-28-2010

Hi,

I have 6 to 7 2960 switches and one router 1800 . As of now , I have configured intervlan communication in router by creating subinterfaces but now since i have one layer 3 cisco switch ( 4503 ) .

I would like replace the router with layer 3 now .

Please guide me ..... and suggest me if i am wrong ... below in my plan

I will keep router as it is with all routes which i have configured in it. To accomplish the requirement of intervlan, i will do it in 4503 switch by creating svi for each respective vlan and i will add one default route pointing towards router

and all existing cascading of all layer 2 switches , I will remove it and i all uplinks will be given from 4503 switch.

If you have any valuable suggestion for me to go ahead with proper set-up .... it would be appreciable.

Please guide me for the same.

Richard Burts · ‎08-28-2010

Vinod

Basically your plan sounds ok. If you move all the physical connections from the switches from the router and make them to the 4503 and create SVIs for each VLAN (may also need to configure each VLAN for the 4503) this should allow the 4503 to accomplish the intervlan routing. Connecting the 4503 to the router with a default route on the 4503 with the router as the next hop will allow routing for any external destination to be done on the router as it has been.

I have a couple of questions and suggestions
- will the link from 4503 to router be configured as a layer 2 access port or as layer 3 routed port? I would suggest it would be better if it were a routed port.

- will the link from 4503 to router be part of an existing subnet of will it be a new and unique subnet? I would suggest it would be better if it were a new and unique subnet.

- the router has previously seen the VLAN subnets as connected routes. This will no longer be true. So you will need to add routes on the router for the VLAN subnets with the 4503 as the next hop.

HTH

Rick

HTH

Rick

View solution in original post

Richard Burts · ‎08-28-2010

Vinod

Basically your plan sounds ok. If you move all the physical connections from the switches from the router and make them to the 4503 and create SVIs for each VLAN (may also need to configure each VLAN for the 4503) this should allow the 4503 to accomplish the intervlan routing. Connecting the 4503 to the router with a default route on the 4503 with the router as the next hop will allow routing for any external destination to be done on the router as it has been.

I have a couple of questions and suggestions
- will the link from 4503 to router be configured as a layer 2 access port or as layer 3 routed port? I would suggest it would be better if it were a routed port.

- will the link from 4503 to router be part of an existing subnet of will it be a new and unique subnet? I would suggest it would be better if it were a new and unique subnet.

- the router has previously seen the VLAN subnets as connected routes. This will no longer be true. So you will need to add routes on the router for the VLAN subnets with the 4503 as the next hop.

HTH

Rick

HTH

Rick

vinodjad1234 · ‎08-29-2010

Hi Rick ,

Thanks for your reply.

I have furnished below details as per your query :

1) will the link from 4503 to router be configured as a layer 2 access port or as layer 3 routed port? I would suggest it would be better if it were a routed port.

Ans : It will be routed port .... but still i would request to get the details .... what is the best practice ?

And you mean to say that , i can configure the ip address on both side with same subnet ( should use existing subnet ) ...... is that enough to make routed port ?

2) will the link from 4503 to router be part of an existing subnet of will it be a new and unique subnet? I would suggest it would be better if it were a new and unique subnet.

Ans : I should use existing subnet ....

3) the router has previously seen the VLAN subnets as connected routes. This will no longer be true. So you will need to add routes on the router for the VLAN subnets with the 4503 as the next hop.

Ans : this is very much true and i will be doing the same thing ...

1 ) I have couple of doubt like what about STP ?

how do i make my switch as a root ... ?

spanning tree priority 0 ... and if i make is it a best practice to have root as a my core switch .

2) can i have two vtp servers in my network ?

If yes ... how do i configure ?

3) It would be great help if i get some configure sample which i can do it in my layer 3 switch for intervlan communication, configure routed port which will connected to router and spanning as well as VTP server which will be one more server in my network ..