schools network

Maints

Hi All,

I am installing a network printer/copier on a schools network. however the vendor of the printer is looking for a static ip address for the printer.
Now, the router that the department of education supplies is a DHCP server which works fine for the pc's on the network but not for the printer.
The DHCP server has a GW of 87.xx.xxx.1 and the first IP it alocates is 87.xx.xxx.10. SUbnet mask is 255.255.255.128 so can allocate IP's up to 87.xxx.xx.127.

A couple of questions then :

1. 87.xxx.xx.2 to 87.xxx.xx.9 appear to be not used....could I use on of these for a static IP for the printer?

2. The 87.xxx.xx.x IP range for this router. Is this static or is it fed from a DHCP server further back ? i.e. I don't want it to change if I assign a ststic IP to the printer.

Any info welcome

Thanks

Paul.

seamus

The IP of the DHCP server/router is probably static. Routers with DHCP IPs just increase the difficulty of managing your routing tables. It's unlikely that they'd spontaneously change the IP subnet - it's possible (maybe even probable) that the router isn't a DHCP server, just a DHCP relay.

Most people setting up a small network will reserve a certain amount of an IP range for static IPs. You can use the 2 to 9 addresses for static IPs, just make sure that you use the correct subnet on any devices.

TimTim

Aren't those IP's internet accessable? Are you sure you want a printer publically available on the internet?

seamus

TimTim wrote:

Aren't those IP's internet accessable? Are you sure you want a printer publically available on the internet?

Assuming the network is run along the same lines as HEANet, although each node is given a public IP address, that doesn't necessarily mean that they're publically accessibly.

The router he has been given probably filters certain types of incoming traffic, and the network that it's connected to is probably firewalled.

Public IP != Publically accessible.

TimTim

Fair enough, its just in my school we have everything on private IP's and then our router doing NAT to provide net access.

seamus

TimTim wrote:

Fair enough, its just in my school we have everything on private IP's and then our router doing NAT to provide net access.

Well, that's the ideal. For whatever reasons though, some places use their public IP range to assign addresses to private, internal networks.

Maints

Having a private address set is how I would normally do it but the departments router was installed and I have no details on how it is setup other than it is DHCP'ing.

If anyone has any details on configuring the router, please let me know.

Paul.

Static M.e.

Sorry perhaps I am missing something here

87.xxx.xx.2 to 87.xxx.xx.9 appear to be not used....could I use on of these for a static IP for the printer?

Yes

seamus

Maints wrote:

If anyone has any details on configuring the router, please let me know.

You shouldn't have to, it appears to be configured. Just give the printer guy one of the IPs between 2 and 9.

Maints

Hi All, Got the following info from the NCTE helpdesk.

Thanks for all the replies.

Paul.



The router in the school is a cisco 871 router and I am afraid it is locked down in every school for security reasons. Please see the description below on why we use public addresses and a description of how safe it is due to our extensive firewalling:


Many schools that currently have broadband are using NAT (Network Address Translation). This is because commercial ISPs typically only give one public IP address to each customer. This means that to use multiple devices, the customer must use private IP space. NAT literally "translates" private IP addesses, and allows devices assigned private IP addresses to access the Internet using the public IP address of the NAT device. This all typically happens transparantly in consumer broadband installations, with the router supplied preconfigured with NAT, and with private IP addresses assigned out by DHCP. Typical private IP ranges are 192.168.1.0/24 and 10.0.0.0/24.

However, schools have been assigned fully publically routed IP ranges - each school is assigned between 32-512 addresses (depending on the number of pupils in the school, though can be assigned upon request). Each address is unique and DHCP is configured to hand out these addresses automatically on the Cisco 871 or UDGateway.

Some of the advantages of using public IP addresses:

* PCs infected with viruses and malware can be identified to the
school (rather than "you have a virus, we don't know where").
* PCs misconfigured for DNS can be identified to the school.
* Schools who run services such email as will be assigned
dedicated IP addresses that will never clash with PCs that may be infected with viruses and end up on blacklists or being blacklisted by the Schools NOC.
* Internet applications such as video streaming and conferencing
can have severe difficulties running in a NATted environment. It is HEAnet's experience that networks that use public IP addresses are easier to support and get applications and services working with.
* Schools attempting to run Internet facing services such as
webhosting and email behind a NAT gateway will be adding additional complexity to the task of getting a simple service running well on the Internet - this violates the principal of "Keep It Simple, Stupid!". Public IP addresses make running services simple, as no awkward port forwarding etc. need be setup. * The use of NAT is not supported in any fashion by the Schools NOC - Schools are unable to obtain support in configuring and troubleshooting their NAT devices from the Schools NOC.

The school is entirely responsible for the design of their LAN (Local Area Network). There is nothing preventing schools from using NAT on their network, however the school should be aware of the advantages of using their assigned addresses. Sometimes schools and/or IT contractors are unaware of the level of content filtering and firewalling that happens on the Schools Broadband network, informing them of this may alleviate some concerns of the use of public IP addresses.



By default the static ip addresses assigned to the school are the first 3 after the default gateway unless you have requested more. It appears that the first ip address in your dhcp pool is .10 and if so then you could use any one between .1 and .10.