Inter-Vlan on Switch and Router Connectivity

[qasimkhans8]

Hi All,

           currently inter-Vlan (Vlan, 9(Users),10(Servers),11(SAN)) is setup on my 3845 Routers. I also have multiple IP NATs on router, which allow internet users to access application running on servers (LAN). I have backup jobs which take backup of servers (vlan 10) and save backup on SAN (vlan 11) due to some reason my router CPU is getting high when backup starts. Please see Current_setup.jpg for my current environment.

I am planning to install 2 Cisco Switches stack-wise and setup Inter-Vlan on Switches. use routers to just Routing the traffic LAN to WAN and WAN to LAN etc...

I need to know how routers and LAN Switches(Sw1,Sw2,Sw3,....) will connect to both Switches and and what config will be required. i just want to move Inter-Vlan on switches and remaining on routers. please see new_setup.jpg for my new environment.

Thanks.

[Reza Sharifi]

Hi,

The new setup diagram is correct.  You basically connect sw3-6 to both switch 1 and 2. Keep switch 3-6 as layer-2 only and move all your inter-vlan routing to switch 1 and 2 in a stack.  Than you need 2 layer-3 routed ports each connecting switch1 and 2 to each router using 2 /30 subnets. In your diagram you have 4 links connecting sw1 and 2 to both routers, but you only need 2 since you are going to stack the 2 switches together and they logically look as one switch.

HTH

[qasimkhans8]

Than you need 2 layer-3 routed ports each connecting switch1 and 2 to each router using 2 /30 subnets.

if i make layer 3 ports on both switches then do i need to make default route from SW 1 to R1 and Sw 2 to R2? how router can send WAN user request to LAN servers?

In your diagram you have 4 links connecting sw1 and 2 to both routers, but you only need 2 since you are going to stack the 2 switches together and they logically look as one switch.

If Sw1 goes down in Stack then R1 will not be able to route traffic. therefore i wanted to have connection with Sw2 as well.

[Reza Sharifi · Accepted solution]

if i make layer 3 ports on both switches then do i need to make default route from SW 1 to R1 and Sw 2 to R2? how router can send WAN user request to LAN servers?

Once you stack them they look as one switch.  The config will apply to the master and master will push the config to member.  So think of one switch.  

You have 2 /30 one pointing to r1 with a default route and the other one to r2 with a default route and higher AD. This is assuming r1 will be your primary and r2 backup.

If Sw1 goes down in Stack then R1 will not be able to route traffic. therefore i wanted to have connection with Sw2 as well.

You still have the other switch that connect to r2 and should route all traffic.

If you are going to have 2 links from each switch you probably want to put both links in a Portchannel.

HTH