Does the portmaster's performance degrade with a lot of
entries in its routing table?
If it does (apparently it does at least to some extent)
then how much and with how many routes?
Look, the solutions presented on the list don't address all the
possibilities. You yourself said "unless you use fixed IPs".
We do use fixed addresses and we can't get rid of them (some
of them use old software not supporting dynamic address assignment,
some want to get mail via SMTP etc). They are just a little
fraction of our user base but the fraction grows as the total
number of users grows.
If a PM can cope with 100 routes with 1% degradation - it's not
a problem, but if it is 10%, well, it is a problem.
Can Livingston give an answer to this question?
Regarding the solutions:
1) Subnetting with 255.255.255.224.
It works fine when the assigned addresses are on the same network
as the portmasters themselves. What happens if you have more than
256 line to serve? You need to assign another C class network to
users. Will the portmasters correctly route this second (subnetted)
network? It depends upon the implementation. Quoting RFC 1058:
"When a host evaluates information that it receives via RIP, its
interpretation of an address depends upon whether it knows the subnet
mask that applies to the net. If so, then it is possible to
determine the meaning of the address. For example, consider net
128.6. It has a subnet mask of 255.255.255.0. Thus 128.6.0.0 is a
network number, 128.6.4.0 is a subnet number, and 128.6.4.1 is a host
address. However, if the host does not know the subnet mask,
evaluation of an address may be ambiguous. If there is a non-zero
host part, there is no clear way to determine whether the address
represents a subnet number or a host address. As a subnet number
would be useless without the subnet mask, addresses are assumed to
represent hosts in this situation. In order to avoid this sort of
ambiguity, hosts must not send subnet routes to hosts that cannot be
expected to know the appropriate subnet mask. Normally hosts only
know the subnet masks for directly-connected networks. Therefore,
unless special provisions have been made, routes to a subnet must not
be sent outside the network of which the subnet is a part."
Portmasters do have special provisions (netmask table). But will
they use them to correctly announce and receive subnet routes?
I don't know. Livingston?
And you still need to cope with fixed addresses.
2) Using static subnet routes on an adjanced router with RIP turned off
This is a bad idea. Apart from the fact that static routing is
prune to errors, this solution doesn't work with fixed IP addresses
at all (even if you happen to have *one* fixed address).
Also all traffic from one PM destined to another one will go
thru the router, which will probably generate ICMP redirect messages
generating a useless traffic (I don't think PMs believe in
ICMP redirects). Having different subnets on a single media
is not a good idea anyway.
So go to the top of the message and please answer the question.
Thank you!
>
> Once upon a time Igor V. Semenyuk shaped the electrons to say...
> >imagine a stack of say 10 PM2e-30 servicing 300 phone lines. You need
> >to turn on RIP on the PMs and set netmasks to 255.255.255.255 in
> >order to make this to work as one unit from the customers' point of view.
>
> Not unless you use fixed IPs.
>
> Use 32 IP subnets, MUCH less routing.
>
> -MZ
> --
> Although I work for Livingston Enterprises Technical Support, I alone am
> responsible for everything contained herein. So don't waste my managers'
> time bitching to them if you don't like something I've said. Flame me.
> Phone: 800-458-9966 support@livingston.com <http://www.livingston.com/>
> FAX: 510-426-8951 6920 Koll Center Parkway #220, Pleasanton, CA 94566
>
>
-- Igor V. Semenyuk Internet: iga@sovam.com SOVAM Teleport Phone: +7 095 258 4170 Moscow, Russia Fax: +7 095 258 4133