lkml.org 
[lkml]   [1999]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRE: howto disable auto route setup?
On Tue, 2 Feb 1999, Fred Reimer wrote:
> I don't remember the RFC that says this either. Try to configure a Bay
> router with a subnet mask less than the class of network for the IP. Can't
> do it. I'd try on a cisco router, but I don't have one available at the
> moment. I doubt it would let you setup an >interface< with an illegal
> netmask either. If it does, then it's a bug.

cisco:
interface Loopback1
ip address 192.168.128.1 255.255.240.0
no ip directed-broadcast

the dev loopback1 used as example.

> Just because we can make it work with Linux does not mean it is the right
> thing to do. If we ever want Linux to be accepted for mission critical
> tasks in the big glass house then it must interoperate with all other
> devices that follow standards. We can't make up our own as we see fit.
> Does Windows support this? What about HP-UX? Solaris? AIX? Digital
> (Tru64) Unix? DG-UX? Irix? VMS? Novell Netware? Cisco routers? Bay
> (Nortel) routers? 3Com routers? OS/2? BeOs? *BSD?
> Name-your-vendor-upon-which-mission-critical-apps-run?

Linux.

and yes, i have seen supernetted interfaces on a few of those.

> If it is not specifically specified in an RFC or other standards document
> that it is now acceptable to "reverse subnet" IP addresses then the answer
> to all of the questions above must be yes for this to be right. If there is
> lack of an official standard, then there must be an "Industry" standard for
> it to be standard. I don't think even a majority of the vendors listed
> above support this, let alone a super majority that would constitute an
> Industry standard.

the term is supernet, not reverse subnet. :)

`RFC' is a request for comments. 'tis generally accepted that these are
standards by which we go. they're made as we need them. they're discussed
and commented on and reworked until we're happy with them.

as networking evolves we need to change our standards to properly accomodate.

i'm sure there are instances where it is beneficial to have a non segmented
supernet. there are generally instances of many exceptions.

using a supernet doesn't make it 'wrong' but simply a different approach.

consider the near future when everything in your house will have an IP.
it's a foolish though that the number of objects will be less than 254, and
probably foolish to consider that they should be segmented. the traffic is
likely to be low, just high object count.

before saying it is illegal or wrong to supernet an interface, simply
consider what is technically detrimental. lack of supernetted
interface/route support? make it happen.

'256' is a figure based on an octet. an octet based on demand. look at
transport protocols. a 53 byte cell for transmission? why such an
oddity..because the math warranted it. how about the 1500 MTU. it's a
figure of the time.

all these figures usually have excellent reasoning behind them however, they
were designed yesterday. if our needs are changing, the numbers need to
accomodate them.

in my previous article, i mentioned adding 128 routes for a /17 supernet.
that was an aside. giving a little thought i'm sure you the reader can come
up with the multi gateway setup required for a /17 supernet and not allowing
supernetted interfaces.

-d
--
Look, Windows 98 Buy, lemmings, buy! MCSE, Must Consult Someone Experienced
__ (c) 1998 David Ford. Redistribution via the Microsoft Network is prohibited
\/ for linux-kernel: please read linux/Documentation/* before posting problems


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:50    [W:0.950 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site