new scope from LA

[TraineeGeek]

Hi,

our school has run-out of IP address ( 123.123.123.x/24 ) so the LA gave us a new scope (456.456.456.x/24). I added this new scope to our Win2008R2 DHCP server but the new scope didn't issue any IPs, I went back to the LA and got this reply:-

 

The switch ports need to be configured into the correct vlan on the switches. I'll need the switch port numbers and the addresses/name of the switches they are connected to and I could do it for you.

 

I don't remember this being necessary in the past (at other schools), so I asked another engineer at the LA and he said both scopes (new & old) needed to be in a super scope, I configured the super-scope and both scopes issued IPs, however the computers receiving IPs from the new scope were unable to see the server shares and connect to the internet.

 

Does anyone know where I'm going wrong? Is the first LA engineer correct and he needs switch info?

 

Thanks

TraineeGeek

 

 

 

[ITGuyWestMidlands]

456? Are you sure? 255 is the max, mathematically

[jamesreedersmith]

I think they are representative of scope a and scope b rather than actual IPS - most likely actual 10.x.x.x etc!

[snagrat]

Either they haven't configured the routing correctly on the router or something is blocking it.

 

What are the individual scope settings you have setup?

 

Do you use any onsite firewall? Do you use Lightspeed at all?

[FN-GM]

You will need to configure a new VLAN, assign an IP address in the new scope to the vlan and then configure switch ports you want into this new VLAN. The LA person is correct.

 

What switches do you have?

[snagrat]

You will need to configure a new VLAN, assign an IP address in the new scope to the vlan and then configure switch ports you want into this new VLAN. The LA person is correct.

 

What switches do you have?

 

We didn't have to do this at all. It just worked.

 

We don't use VLANs at all

[FN-GM]

We didn't have to do this at all. It just worked.

 

We don't use VLANs at all

 

Was your scope expanded rather than an additional one added? Or maybe the whole range was replaced?

 

You cannot have 2 separate subnets in the same LAN, things will just not work properly. Each LAN can only have 1 subnet for things to work properly.

[snagrat]

Was your scope expanded rather than an additional one added? Or maybe the whole range was replaced?

 

You cannot have 2 separate subnets in the same LAN, things will just not work properly. Each LAN can only have 1 subnet for things to work properly.

 

No we had an additional one. We have 10.130.x.x and 10.144.x.x both with different subsets.

 

SWGfL did stuff on the router to allow both to talk to each other. Nothing done on our switches and all I did was to create a superscope

[TraineeGeek]

sorry yes, just representative. I should have done it differently.

[ITGuyWestMidlands]

Possibly need an ip helper on the router so that it routes dhcp broadcasts between the two networks

[TraineeGeek]

From my original (poor) example:-

456.456.456.x

255.255.255.0

 

The gateway is the gateway on the original scope, which I thought was odd. So from my original example 123.123.123.254

 

- - - Updated - - -

 

Cisco can't remember the which models but I'll find out tomorrow.

 

- - - Updated - - -

 

It was an additional scope. I then created a superscope with the old and new scope.

[snagrat]

From my original (poor) example:-

456.456.456.x

255.255.255.0

 

The gateway is the gateway on the original scope, which I thought was odd. So from my original example 123.123.123.254

 

- - - Updated - - -

 

Cisco can't remember the which models but I'll find out tomorrow.

 

- - - Updated - - -

 

It was an additional scope. I then created a superscope with the old and new scope.

 

Each sub scope should have its own gateway.

 

123.123.123.x

255.255.255.0

123.123.123.254

 

456.456.456.0

255.255.255.0

456.456.456.254

 

I router will be configured to have both IP addresses.

 

If you put something on the new range as a fix IP can you ping the gateway?

[TraineeGeek]

Pretty sure the helper IP address has been added

 

- - - Updated - - -

 

All CISCO

[synaesthesia]

Frankly, that's a horrible and antiquated way of doing things; what exactly does any LA think a school can do with a /24 these days? There's a 60 pupil primary near me that has problems with it! Personally I'd suggest asking them if you could/they could help set up a NAT so you can have whatever range you wish in-house such as a /22 and they handle the routing, if they can manage something that simple? If you're having to change things around anyway you might as well save yourself problems later on and do it properly now.

[TraineeGeek]

Hi,

asked about a /23 and got this response:-

"That’s the whole idea of the vlans, it cuts down on the broadcast traffic and the 2 vlans don’t run consecutively so it can’t be made into a /23 subnet, the only way around this is to vlan the switch ports correctly."

[FN-GM]

The LA is right. You wouldn't want to make it into a /23. Have 2 separate VLANS. Its not recommended to go below a /24 per VLAN.

[synaesthesia]

This isn't 1999 though. Broadcast traffic isn't at all bad for workstations and there is nothing wrong with a /22 let alone a /23 (we have 2 x /22's for workstations). Definitely agree when you start putting crap like printers and monitoring systems into the mix, the former tend to flood networks with so much crap I often wonder why we don't stick with locally connected Centronics printers.

[FN-GM]

This isn't 1999 though. Broadcast traffic isn't at all bad for workstations and there is nothing wrong with a /22 let alone a /23 (we have 2 x /22's for workstations). Definitely agree when you start putting crap like printers and monitoring systems into the mix, the former tend to flood networks with so much crap I often wonder why we don't stick with locally connected Centronics printers.

 

Broadcast is a bad thing for the entire network. Why do you think it was removed in IPv6? There is something wrong with /22 and /23 and they should be avoided at all cost.

[synaesthesia]

*hides his /20 for wireless*

[FN-GM]

*hides his /20 for wireless*

 

wow! /20

 

I have a /22 wireless for BYOD admittedly. However I am looking at way to drop broadcast traffic.

[synaesthesia]

Not having any issues whatsoever with ours. We run a /22 for each physical site and /20 overall for wireless, covering both standard & guest. The only issues we had with traffic were prior to vlanning and stemmed from our Xerox printers which chatted enough to make Alan Carr seem quiet and retiring.

I always used to work on a /24 max until Windows 7 came about due to the changes MS made - I think it was DNS or similar that was "fixed" and cut broadcast traffic from standard clients in half.

I must admit I used the same logic (workstations won't bother a /22) to justify a lazy /20 for wireless and only this discussion has made me think "hang on, this VLAN is full of devices like iPhones, Androids and cheap Chinese in-betweens, why on earth did I apply windows standards to them?"

I might stick a PC on that vlan soon and run wireshark out of interest!

[FN-GM]

You will be surprised when you get out Wireshark. Even Windows does it, most of it is down to the install applications and not the OS itself.