2

I have currently the following situation:

ISP-Router --> Own NetGear Router (in DMZ of ISP-router) --> 28p Cisco Switch --> devices and AP

The ISP-Router only hands out 4 IP-addresses. I have more than 4 devices, so I added an aditional router to hand out more IP-Addresses. So my ISP thinks that I use 2 IP-addresses: 1 for the Netgear Router, 1 for my Harddisk recorder that needs to have an IP from the ISP. (Telenet in case you are wondering).

What I want to know, is that if it is possible that I can connect my Cisco Switch to my ISP-router directly without leasing more than 4 IP-addresses.

ISP-Router --> 28p Cisco Switch --> Devices and AP

Is it possible to accomplish this with VLANs? For example VLAN1 gets IP-addresses from the ISP-Router, VLAN2 is my home network where the Cisco switch hands out IP-addresses to my devices. Offcourse, all my devices should be able to connect to the internet (which is managed by the ISP-router). I would like to have my home network to have it's own address range (different than the ISP range).

Hopefully an easy question for you guys. I'm just learning here :-). If you need more info, please ask.

Improve this question
4
  • Why the downvote?
    – rtf
    Oct 12, 2016 at 13:45
  • I too often find incomprehensible downvotes, always without an explanation. I too take it upon myself to redress the situation.
    – MariusMatutiae
    Oct 12, 2016 at 13:49
  • Your hardware would need multiple physical LAN ports. Once you have hardware with multiple LAN ports, you can setup VLANS at that point, just like if you had multiple routers going to your switch.
    – Ramhound
    Oct 12, 2016 at 14:23
  • What do you mean with hardware? All my devices?
    – Mr. T.
    Oct 13, 2016 at 10:59

1 Answer 1

Reset to default
1

A switch does not need an IP address, unless it is managed. I am not sure I have identified correctly your switch but, if it is this one, then it is managed, and it will need one IP address from your ISP router.

The machines attached to the switch do not need an IP address in order to talk to the switch, but they will ask one to talk to the internet to the ISP router. Your faithful switch will pass along their requests to the router, which will quickly exhaust its really tiny pool of IP addresses, and you will be in trouble.

Your first configuration made much more sense, and allowed a very large number (up to 253) of clients to the DHCP server on the Netgear Router.

As for VLANs, even if they were allowed by the ISP router, each with four maximum clients, it would still amount to a total of 16 clients (much less than the 253 mentioned above), which would also have trouble talking to each other.

Improve this answer
7
  • I have the SG500-28p. My actual goal is to create a vlan of 4 ports (DHCP with ip-addresses from the ISP) and a VLAN of 20 ports using the DHCP server of the switch itself and in another range than the range of the ISP.
    – Mr. T.
    Oct 12, 2016 at 14:34
  • So for example: VLAN1: Network 192.168.0.0 with 4 IP Addresses max VLAN2: Network 172.10.30.0 with x IP Addresses But the devices connected to VLAN2 should be able to connect to the internet.
    – Mr. T.
    Oct 12, 2016 at 14:37
  • @TonyVerbert Yes, that's fine. But remember that 1 of the four addresses in 192.168.0.0/24 is the switch itself: like I said, a managed switch requires an IP address.
    – MariusMatutiae
    Oct 12, 2016 at 15:26
  • Thanks, I understand that. It will be a DHCP client from the ISP. Now one security question about the new situation: Is the Cisco Switch 'safe' enough to be in the DMZ of the ISP-Router?
    – Mr. T.
    Oct 13, 2016 at 9:25
  • @TonyVerbert What is safe enough? All I can tell you is that there is no known exploit affecting it as of now, I just checked.
    – MariusMatutiae
    Oct 13, 2016 at 9:32

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .