SGE2000P - InterVLAN Routing & internet Gateway

[WoodsieLordShab]

Hello everyone,

I've been reading articles and forum discussions for a while now, as I'm gathering information before designing any network modifications or making purchases.

Currently, we have a plain network and we are planning to 'upgrade' it a little. We want to implement VLANs to separate wireless clients, workstations + servers and infrastructure devices form each other.

As of now, we have no VLANs, and no managed Switches. We only have an RV016 that handles two ISPs and a 3rd party connection service to the office branches ( I belive they're using Frame Relay, but as far as we know, we are not concerned since we cannot touch their devices)

The reason behind the title, pointing towards the famous SGE2000P, is that my workplace is located in Argentina... and we don't have as many choices as some of you guys have ! In fact, I was unsuccessful trying to get a Cisco partner to contact me. We would like to replace the RV016 with a cisco 1941 (and a HWIC switch card).

So, back to business..! Assuming we will be using the SGE2000P switches, I was thinking about setting VLANs using 802.1Q through seven of these switches, along with a 1941 Cisco router. I'm expecting the 1941 to handle load balancing between both ISPs and the 3rd party link. Now, as for Inter VLAN routing, I would like to have gigabit traffic between VLANs. It's not imperative but it would be a nice and welcomed feature, (by the way, our current network runs at 10/100 speeds. I know, it's hard to belive, but it's the truth!).

so, my question is...

Is it possible to use one SGE as Layer 3 mode to hande inter VLAN traffic (gigabit speeds) while using the 1941 as a end point device to reach internet (using PAT) ?

Would you suggest me to use the 1941 for Inter VLAN routing, despite the 10/100 limitation(*) and use all SGE's in L2 mode?

(*): We need two ISPs, a third link for the FR connection, and finally the LAN interface. As far as I know, I'm limited to the gigabit builtin interfaces for WAN purposes, am I right?

Thanks in advance!

Agustin.

[Tom Watts · Accepted solution]

Hi Agustin, the switch is capable to handle inter-vlan traffic in layer 3. The trick to make it work is to ensure the default gateway of connecting hosts to be that of the SVI they are a member of.

I would highly recommend you do not use the stack feature of these switches especially if you plan to have 7 of them. The stack implementation is kind of poor and may provide reliability issues especially in layer 3 mode.

I think it is probably better to have the switch manage most routing before it goes to the router, it should help network performance as it would aggregate the traffic.

You would need only 1 of the SGE in layer 3 mode, the rest should remain layer 2 mode unless you have a specific reason otherwise. For network performance, the other 6 switches should be layer 2.

-Tom
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[WoodsieLordShab]

Thanks Tom,

That's what I had in mind, more or less!. If I got this right, the connection between the L3 switch and the router should be standard non-tagged / not trunk. Am I wrong? Will the 1941 be able to handle PAT for clients from any VLAN?

thanks again!

[Tom Watts · Accepted solution]

I don't know what that router can do. If I remember right the 1941 supports sub interfaces so you just make the sub interfaces with dot1q encaps and that should take care of it. The universal trick is to make sure the router knows about the subnets... so it will be accomplished through dot1q, static routes, whatever.

-Tom
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[WoodsieLordShab]

Thanks for the quick response, Tom
this is a buggy 'sketch' of what I had in mind:

>>> So, the L3 configured switch would handle all inter VLAN routing while the '3rd party connection' and the default route (internet) would point towards the 1941.

As far as I know, the cisco 1941 allows you to create subinterfaces, I also checked that PAT will work. I just need to mark each subinterface as Nat inside.

Thanks again!

Edit:

I was wondering... the L3 switch should be able to route each VLAN to the 1941 as last resort... problem is, each VLAN should be routed by the L3 switch to each of the Router's subinterfaces respectively, right? ...Is this possible?

[Tom Watts]

So long as the default gateway of the hosts are that of the SVI of the switch, the switch will locally route traffic until a request is needed to go to the 1941. From there the 1941 should be able to handle the request based off the subinterface as it would be a routed interface.

-Tom
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