On Wednesday, 01/14/2009 at 10:36 EST, "Lionel B. Dyck"
<lionel.b.d...@kp.org> wrote:
> I need to find a subnet that isn't used internally that I can define for
use
> strictly on each individual CEC between z/vm+linux and z/os across a
> hipersocket link. It seems our network folks are using all of the
defined
> public subnets somewhere within our internal network which precludes
using any
> of those for use within the CEC.
>
> Someone suggested using the IBM subnet (9.x.x.x) but I can not find any
doc
> that 'blesses' such a use.
>
> Any advice/direction?
Ask them again; perhaps they didn't really understand the question. That
answer implies that (a) they don't know how to use private IP addresses
and subnets, (b) existing subnets are improbably large, and (c) KP cannot
add new subnets *anywhere* in its internal infrastructure. This boggles
the mind.
RFC 1918 defines the following as 'private' meaning that we have a
Gentlemen's Agreement not to route them beyond the networks that we
administer unless we mutually agree to allow them. (Routers will not, by
default, forward them.)
10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)
Your network people can, of course, use smaller subnets. You could
unilaterally choose an address in those ranges, but you would have to
ensure that they do not get used elsewhere in your internal networks.
(This is why we have Networking People.)
In reality you can use any IP addresses you want - no one can stop you.
But if you use someone else's addresses you create risk. It is up to IBM
to place or not place 9. addresses on the Internet at its discretion. (I
think our 9s currently appear as 129.42s.) So no one will countenance
your use of 9., and I would expect severe frowns from professional
networkers.
Alan Altmark
z/VM Development
IBM Endicott
