RE: [suse-linux-uk-schools] address ranges
Thanks Andrew, One of the issues is that subnetting on this system bears no relationship to topology. e.g. all servers are 192.168.0.1-50; clients with static IP are 51-254. Others get IP via DHCP in the range 1.1 to 2.254 - he's treating the network as being unstructured - which it isn't. I think this is generating loads of unnecessary traffic through switches. Hence he's using subnets as a way of extending the address range rather than as a way of clustering services either physically or logically. D -----Original Message----- From: Andrew RAY [mailto:aray@computerpark.co.uk] Sent: 15 September 2003 15:10 To: suse-linux-uk-schools@suse.com Cc: Grainge, Derek; chris@centralmanclc.com Subject: RE: [suse-linux-uk-schools] address ranges I agree with Chris, but I'm surprised that, as yet, no one has looked at the reason for sub-netting. Just 'because it exists' is a bad reason. A good reason is where discernible groups need access to peculiar resources. These could be: a) A particular server/servers (could be special mail/file-print/proxy servers for the group of machines on the sub-net). b) Specific network printers. c) Other special shared network resources (web-cam; PLC control technologies(!!); robots; turtles etc etc). By sub-netting and locating the identified resources on the appropriate sub-net, then access is made very easy for those who share that sub-net, but not necessarily denied to less frequent users who may live on another one. In this way, each sub-net can concern itself with the resources which are *predominantly* for its users, and in a way which is commensurate with this, the network traffic is *generally* limited to those switches / routers (depending upon the methodology used on your physical network) that deal with the identified sub-net. By planning network resources around places of need, essential sub-net divisions should really present themselves. It is these that then become 'categorically' good things. Hope this helps further. Andrew
The use of subnets is categorically a good thing; this prevents broadcast traffic from slowing the network down and is a useful way of providing QoS - the downside is lag between subnets if you use a router rather than layer 3 switching. You also need to provide services to resolve netbios names e.g. WINS, and have a method of providing DHCP support.
We use layer 3 to support 20+ class C and below subnets without any issues (W95/8,NT, 2000, XP, Linux, Unix). What concerns do you have on his behalf?
Chris
-----Original Message----- From: Grainge, Derek To: suse-linux-uk-schools@suse.com Sent: 9/15/03 9:47 AM Subject: [suse-linux-uk-schools] address ranges
A colleague (a real colleague not me pretending!) has a network which has grown like topsy. It consists of 8 class C addresses covering 192.168.0.0 - 192.168.7.255 He's operating a mixture of platforms including the odd linux server but a number of W2000 ones.
I think he should take the time and trouble to use a single class B range instead. Can any network guru tell me - is it a) necessary or b) desirable?
Thanks in advance, Derek
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Derek Further comment interspersed ...
One of the issues is that subnetting on this system bears no relationship to topology. e.g. all servers are 192.168.0.1-50;
... which *guarantees* a huge amount of traffic through your switches
clients with static IP are 51-254. Others get IP via DHCP in the range 1.1 to 2.254
... which guarantees a whole load more.
Hence he's using subnets as a way of extending the address range rather than as a way of clustering services either physically or logically.
... in a situation like this it would cause less network overhead to remove the subnetting! But of course, it would be better to group resources as discussed earlier, and, yes, have servers and service providers at one end of each sub-net range (including the DHCP servers), but *group* them with appropriate clients. Then you get the best of both worlds, as I'm pretty sure from your reply that you already suspected. Good luck with the imminent battle. Andrew
-----Original Message----- From: Andrew RAY [mailto:aray@computerpark.co.uk] Sent: 15 September 2003 15:10 To: suse-linux-uk-schools@suse.com Cc: Grainge, Derek; chris@centralmanclc.com Subject: RE: [suse-linux-uk-schools] address ranges
I agree with Chris, but I'm surprised that, as yet, no one has looked at the reason for sub-netting. Just 'because it exists' is a bad reason.
A good reason is where discernible groups need access to peculiar resources. These could be:
a) A particular server/servers (could be special mail/file-print/proxy servers for the group of machines on the sub-net).
b) Specific network printers.
c) Other special shared network resources (web-cam; PLC control technologies(!!); robots; turtles etc etc).
By sub-netting and locating the identified resources on the appropriate sub-net, then access is made very easy for those who share that sub-net, but not necessarily denied to less frequent users who may live on another one. In this way, each sub-net can concern itself with the resources which are *predominantly* for its users, and in a way which is commensurate with this, the network traffic is *generally* limited to those switches / routers (depending upon the methodology used on your physical network) that deal with the identified sub-net.
By planning network resources around places of need, essential sub-net divisions should really present themselves. It is these that then become 'categorically' good things.
Hope this helps further.
Andrew
The use of subnets is categorically a good thing; this prevents broadcast traffic from slowing the network down and is a useful way of providing QoS - the downside is lag between subnets if you use a router rather than layer 3 switching. You also need to provide services to resolve netbios names e.g. WINS, and have a method of providing DHCP support.
We use layer 3 to support 20+ class C and below subnets without any issues (W95/8,NT, 2000, XP, Linux, Unix). What concerns do you have on his behalf?
Chris
-----Original Message----- From: Grainge, Derek To: suse-linux-uk-schools@suse.com Sent: 9/15/03 9:47 AM Subject: [suse-linux-uk-schools] address ranges
A colleague (a real colleague not me pretending!) has a network which has grown like topsy. It consists of 8 class C addresses covering 192.168.0.0 - 192.168.7.255 He's operating a mixture of platforms including the odd linux server but a number of W2000 ones.
I think he should take the time and trouble to use a single class B range instead. Can any network guru tell me - is it a) necessary or b) desirable?
Thanks in advance, Derek
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-- Email: aray@computerpark.co.uk --------------------------------------------------------- This private and confidential e-mail has been sent to you by Computer Park Ltd. If you are not the intended recipient of this e-mail and have received it in error, please notify us via the email address or telephone number below, and then delete it from your mailbox. Email: mailbox@computerpark.co.uk Tel: +44 (0) 1536 417155 Fax: +44 (0) 1536 417566 Head Office: Computer Park Ltd, Broughton Grange, Headlands, Kettering Northamptonshire NN15 6XA Registered in England: 3022961. Registered Office: 6 North Street, Oundle, Peterborough PE8 4AL =========================================================
participants (2)
-
Andrew RAY
-
Grainge, Derek