network implementation

Paul Civati paul at
Tue Sep 10 16:13:24 BST 2002

"Julian Morgan" <jmorganstarnet at> wrote:

> The location - which is about 50kms away wont effect the IP addressing and 
> domain hosting/resolve if we stay under the same isp and carrier that the 
> web system is at the moment.....  the webservers are located at someone 
> elses premises - but they have been there for a long time - and we have been 
> operating for a year or so..  we have our own line in - so I would assume 
> that the IP range provided by uunet has only our machines on it - so we can 
> keep the those IPS if we relocate to another network..  therefore requiring 
> hardly any reconfig right???

If you are staying with UUNet then yes I should think that they will
re-route the IP block for you, providing you're not sharing the subnet
with someone else.  But you really need to speak to their support people
to confirm that, and not just take my word for it. ;)

[ background as to why IP blocks can't be moved between ISPs, for anyone
interested ... ]

Generally speaking, IP blocks are assigned to ISPs in big chunks that
are not allowed to be split up (PA - Provider Aggregatable), this is to
ensure that the growth in routing tables is kept to a minimum on ISP
routers across the internet.

For example, if UUNet are assigned a /16 sized IP block, then they
announce one /16 route, if people moved smaller sized blocks to other
ISPs the other ISPs would have to announce those separate blocks.  So
you might well end up with lots and lots of /24 routes if people were
allowed to split up the larger sized blocks.

Sometimes there are special circumstances that mean people get their own
small blocks (PI - Provider Independent) that are independent of ISP, but
this is a special case for people doing things like multi-homing, and has
certain requirements attached to obtaining such a block.


More information about the Ukfreebsd mailing list