Messages in this thread | | | Date | Tue, 2 Feb 1999 10:49:38 -0500 (EST) | From | "Richard B. Johnson" <> | Subject | Re: howto disable auto route setup? |
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[SNIPPED (most all)] > > Vaguely on this topic, I've been wondering if it's legal/advisable/safe > to have a netmask like 255.255.254.0 ? >
Yes. My netmask is 255.255.248.0 My network runs from 204.178.40.1 -> 204.178.47.255 204.178.40.0 is the "network" address, 204.178.47.255 is the "broadcast" address. Because of some defective software in some machines, we don't use 204.178.40.255, 41.255, 42.255, 43.255, 44.255, 45.255, or 46.255 because some machines think that these are broadcast addresses. The machines that abuse these addresses are M$garbage machines.
The idea of class A->C networks has come and gone because of the lack of suitable continuous addresses defined by the original standard. It is now common to make large networks using contiguous small networks. The netmask is the thing that defines the "network". Stuff that doesn't fit through the mask is sent/received through the "default" route. Once this is understood, configuring a network is simple.
> Anyone? The HOWTO is rather ambiguous about it. I think it's legal, > but am not entirely sure. This also seems to imply a broadcast addr. of > something like 194.111.1.255 for a network address of 194.111.0.0, > presumably that's OK too?
The broadcast address is the IP number that will be put into packets that have a hardware destination of ff:ff:ff:ff:ff:ff (did I put in enough). These packets are received by everyone on the LAN. They will be received regardless of the IP number contained therein. For compatibility, its a good idea that the address be within the LAN range, and contain .255 as its last number. However, some OS don't care because they never check. Stuff that goes out in the Internet is changed and cleaned up by the router. Ethernet hardware addresses are not used on a WAN (like the Internet).
Cheers, Dick Johnson ***** FILE SYSTEM WAS MODIFIED ***** Penguin : Linux version 2.2.1 on an i686 machine (400.59 BogoMips). Warning : It's hard to remain at the trailing edge of technology. Wisdom : It's not a Y2K problem. It's a Y2Day problem.
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