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this is my lab: I have the switch netgear gs724tv4, I have a modem router for Internet access with dhcp that can lease only 5 ip addresses.

The ip subnet for the modem router is 192.168.1.0/24

I would like to create a vlan on the switch with a separate dhcp (I'll put a nas in this vlan as dhcp server) with the subnet 192.168.0.0/24 where all pc's are members and a vlan where the modem router is the only member. The dhcp of the modem router should only lease ip addresses for wireless devices (the modem router is also wireless) and not to the vlan where pc's are members but the pc's should use the modem router as default gateway to access internet.

The modem router cannot be configured so I need to leave the configuration as it is and I cannot connect a router between the switch and the modem router.

I know my switch has vlan routing capability...I tried several configurations but I was unable to allow Internet access on the vlan where pc's are members...any idea?

Thanks in advance

Maxrock70
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  • Hi, my lab is a real office environment, I need to provide this solution for a small office and the products used for this lab professional devices not for home users...even the subject, vlan's, is not for an home environment. Thanks – Maxrock70 Oct 11 '14 at 18:50

1 Answers1

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Using two switches would trivially solve your problem trivially. However, you can isolate the switch into two virtual switches using VLAN. Using Netgear's untagged VLAN function, you can let all clients does not aware there exist VLANs; for them, it just looks like there is two separated switches. It means you configure clients as if there is no VLAN; so the modem router does not need any special settings for your switch.

  1. Create a VLAN (since you already have one, a default VLAN 1).
  2. For each port, assign one of the two VLANs as Untagged.
  3. Assign a same number for PVID to each port.

PVID is for tagging VLAN ID to each packet for the switch and the switch remove the VLAN tag as packet departs untagged VLAN port.

Jihun
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  • Jihun, but if the two vlan are isolated from each other, how can clients on default vlan can use the modem router as default gateway on new vlan? Can I have more details on this? – Maxrock70 Oct 12 '14 at 07:33
  • The PCs cannot use the modem router since you configured so, unless you use the nas as a router. You do not touch the modem router which is 192.168.1.0/24 while you use 192.168.0.0/24 for PCs. Thus, the modem router is isolated by your configuration. Something should route between them. Isn't it your intention? If not, what is a goal of your configuration? Perhaps, you need to reconsider your configuration. – Jihun Oct 13 '14 at 06:12
  • Yes, this is exactly my intention...I was thinking that the route between the two vlan's could be possible with a vlan routing (my switch has this option) can the vlan routing solve this problem? The objective of the configuration is to have the modem router on vlan 10 and the pc's on vlan 1 to be able to use the modem router on vlan 10 as gateway for Internet...is it possible? – Maxrock70 Oct 14 '14 at 06:15
  • I think, no it's not. Either you change the modem router's configuration or you need another router to connect two VLANs. Only clients 192.168.1.0/24 can communicate to the modem router and you will not give PC clients such IPs. Thus, in this setting, PC clients cannot use the modem router whatever you configure the swich which is L2 switch. I found that [this link](http://kb.netgear.com/app/answers/detail/a_id/8898/~/2-vlans-accessing-internet-using-layer-2-switch-%26-router) is most close to your configuration. But it also use a router that supports VLANs. – Jihun Oct 14 '14 at 07:01
  • Ok so it means that I need a router vlan aware where I can specify a different default gateway for each subnet in each vlan right? – Maxrock70 Oct 14 '14 at 10:00
  • Yes, you need a router. But I doubt specifying a different default gateway is necessary; the modem router will ignore them anyway unless you configure the modem router to accept them. Instead, the router need to be attached to a lan port of the modem router. – Jihun Oct 14 '14 at 11:17