VLAN Clarification Required

[spc-rocket]

@ICTNUT,

 

I would seriously consider a Layer 3 switch to do the routing rather than the cisco router because layer 3 switch does HW routing (ASIC based) rather than software which is slower.

 

I would advise you use something like the Catalyst 3550 or even better Catalyst 3750 series switches.

 

You mentioned the IP helper command, the way it works it that when the switch recieves a request for an IP it then converts it to a unicast packet and sends it to the DHCP server's VLAN and the DHCP server will think its come from its own vlan but the gateway address is different and hence it will pick the correct scope to get an ip from and deliver it to the layer 3 switch which will forward it to the correct client on the correct vlan.

 

you will not need to run any routing protocols as well this way becvause the layer 3 switch will have the routes available to all vlans unless you put an ACL to deny traffic from one vlan to another say.

 

 

HTH,

 

Ash.

[ICTNUT]

@Ashok: I agree with you that a layer 3 swicth would solve the problem however as usual this is needing to be done on a budget and the Catalyst 3750 is the best part of £4k.

 

The Cisco 2651 I have picked up brand new and sealed under warranty for only £275 from a supplier of mine.

 

I agree there maybe a performance hit but I don't think it will be really noticeable.