Connecting switches together with IP routing

[Shibu1978]

Dear All,

I have a question .. pl guide me           

CiscoSwitch1(4506) has 3 VLANs(12,13,14) and Switch2(4948) has 3 different VLANs(22,23,24) and IP routing has been enabled in both switches with SVI interfaces for each vlan. intervlan routing is works fine.

Now there is a requirement to connect these switches together. Vlan 12 on the Cisco switch 4506 has to be made available from vlan 22 from Switch2(4948).  basically Vlan 12 is having a multicast source (225.0.0.0 & 226.0.0.0) which should be accessabile from vlan 22 of  cisco switch 4948.

I got 2 ideas

1)  Create a trunk between these switches and configure L2 vlan(12) in cisco 4948...i know theoritically it should work but what my concern is Ip routing enabled in both switches will it create any issues? is it a gud solution to this requirement?

2) Create a separate IP network on the ports connecting to both switches and set up routes to the networks.

ex- console(config)#ip route 192.168.10.10 255.255.255.0 192.168.20.1

Since multicast is going out from the connected interface will this be a gud soultion? is there any issues ?

kindly get back to me .

Thanks
Shibu

[Reza Sharifi]

Hi,

Since the 4500 has its own SVIs for its local vlans and also the same for the 4948, you need to connect the 2 switches together using a layer-3 link with a /30 subnet.  You than need to use static routes on the 4500 to reach the subnets/vlans on the4948.  You also need static routes on the 4948 to reach the vlan/subnets on the 4500. Also need to enable multicast with PIM on the SVIs and layer-3 link and create vlan 12 on the 4500.

HTH

[Shibu1978]

Hi,

Thanks for the reply.

Since Cisco 4506 is a very critical switch with IPTV traffic is running i dont want to enable multicasting routing with 4948 switch. if some issue happens especially in multicast domain due to this integration it will be a complete disaster.

What would be my first idea? will it work with my requirement?

1) Create a trunk between these switches, allow vlan 12 on it and configure vlan 12 as an L2 vlan in cisco 4948. since IP routing is enabled in both switches will this method works for me.

Meanwhile could you suggest is there any other method through which i can accomplish the above requirement.

Thanks for u r time

[Shibu1978]

Could some one shed some more light on this....thanks

[Reza Sharifi]

Hi,

I am not sure, why you are so concern about turning on multicast on the 4500 switch.  Running multicast should not cause any issue.

You basically have 3  local vlans on the 4500 (12, 13 and 14) with SVIs.  You also have 3 different vlans on the 4948 (22,23 and 24) all local. 

now vlan 12 (multicast source) on the 4500 needs to communicate with vlan 22 on the 4948.

Ok, you can connect the 2 switches together and configure vlan 12 on both sides, but make sure the SVI is on the 4949.

So, now vlan 12 and 22 can communicate since both SVIs are located on the 4948.  Just remember the other vlans on the 4948 (23 and 24) will not communicate with vlan 12. Is this what you are looking to do?

HTH

[Shibu1978]

Since multicast is not possible to enable in 4948 due to some internal issues  i have to use some other method to get this working.

The below workaround is what i am trying.

1) Trunk these switches together and allow only vlan 12 on it.

2) Create l2 vlan-12 in 4948     ( 4948 is having other two vlans (23,24) and IP routing enabled ). i dont need this vlan 12 to communicate with vlan 23,24 in 4948.

3) SVI interface for this Vlan is being configured 4506.

4) Assign vlan 12 in one of the gig interface in 4948 and assign the IP range of vlan 12.

Will this method works ? Can the PCs on the vlan 12 in 4948 reach the SVI in 4500 through thr trunk and works for my requirement.

Thanks for your time.

[Shibu1978]

Dear Reza,

Could you comment on the above point which i have planned...thanks

[Reza Sharifi · Accepted solution]

Yes, you solution should work.  Basically vlan 12 is layer-2 only on the 4948 and layer-3 (SVI) on the 4500.  Vlan 12 SVI should communicate with all other vlans on the 4500.  Since vlan 12 is the only vlan on the Gig link between the 4500 and the 4948, and you don't want this vlan to communicate with other vlan on the 4948, you can simply use this link as an access port.  Trunk port works too.

HTH

[Shibu1978]

Thanks for the clarifications...