per Port DHCP on a switch...please help!

[tshen83]

Hi,

I am searching for a solution at a networking problem:

Like a router, where there is a DHCP server on the router,
I need a 12, 16 or 24 port switch that is able to assign specific, preconfigured IP address to each individual port.(ie 192.168.0.1 to port 1 via DHCP protocol, 192.168.0.2 to port2, so if I plug a DHCP client device into port 1, it will get 192.168.0.1 as its address, plug the same device to port2 gets 192.168.0.2)

The switch also needs to be SNMP capable for monitoring, so it's probably going to be a managed switch.

Anyone know of a solution? please let me know.

 

[Kelemvor]

You could probably doign it by setting up VLANs or something if you have a programmable switch but that'd be a bit of work. I don' thave an answer but it's an interesting question and I'll look forward to someone else answering it...

 

[spidey07]

can't really be done with a layer2 switch.

You'll need a layer3 switch with each port in it's own vlan. That layer3 switch could also provide DHCP services. So each port would be it's own network.

 

[nweaver]

Yes, you cannot do layer 3 stuff with a layer 2 device. Your absolute worst case had to do it thing would be to router on a stick, and a DHCP server with iphelper enabled, but it would be ugly , and as mentioned above, every port is a private network.

 

[tshen83]

i did a freaking ton of research lately, and only few Level 3 Switches support DHCP relay agent Option 82 RFC 3046.

The ones that does work are: Netgear FSM73xx series, Cisco IOS based Layer 3 Swtiches.

We will be using ISC DHCPD server, however google turns up very few instructions on how to configure the ISC DHCPD server to use the agent.circuitID provided by the option 82 feature on the Layer 3 Switches mentioned above

please help!

 

[Tazanator]

well next option is a multiport router .. I did see an Imagestream Gateway configed like this once ... it was a nightmare to config and a salty price but it did the job when finished. had an OC-3 in and 2 gig ethernet and 16 10/100 NIC's out. They did exactly what you are asking for here but it makes a very hot box and a high cost.

 

[nweaver]

Originally posted by: tshen83
i did a freaking ton of research lately, and only few Level 3 Switches support DHCP relay agent Option 82 RFC 3046.

The ones that does work are: Netgear FSM73xx series, Cisco IOS based Layer 3 Swtiches.

We will be using ISC DHCPD server, however google turns up very few instructions on how to configure the ISC DHCPD server to use the agent.circuitID provided by the option 82 feature on the Layer 3 Switches mentioned above

please help!

Get a normal DHCP server, MS ones work easily with this. We run a Cat6500 with this type of setup, single addy DHCP that serves IP's to 6 different VLANS from 6 diff scopes

 

[tshen83]

what's the performance penalty of having each port as its VLAN(latency, bandwidth throughput)

 

[spidey07]

none, providing it is a real layer3 switch.

But more importantly, why are you needing to do this? There could be a much more simple solution depending on what you want to do.

 

[tshen83]

http://www.hardforum.com/showthread.php?p=1029160852

why i want to do this is discussed in the concurrent thread in the hardforum. looks like single IP scope on each VLAN is the only way of accomplishing this now.

 

[spidey07]

well it seems like you have your solution then.

should do exactly what you want it to do.

I'd make the mask a /28. that gives you 6 IPs for each subnet. Or if you want use a /30 for only two IPs per subnet (one would be the switchport and the other would be the host)

pretty easy to configure. If fact I would acutally turn the ports into routed ports with the no switchport command. That way it looks like you are plugged directly into a router and you won't have to mess with vlans, flooding, etc. As far as routing if you use a /30 you can summarize the whole thing into a /24 routing advertisement. I don't know about the rest of the network or routing protocol in use.