SunOS 4.1.4 - network classes and netmask / broadcast a ddresses

SYNOPSIS:

Did not know my ABC of network classes like I thought I did. Was trying to

assign a class C submask to a class A network IP. Needed to add the fully

qualified network number for my class A network into file /etc/netmasks to

get correct netmask. Made the following entry into the file

/etc/netmasks...

10.0.0.0 255.255.255.0

then reboot and all is now fine.

OS:

SunOS 4.1.4

HARDWARE:

Sun SPARCstation 2 -thru- SS20

ORIGINAL QUESTION:

Netmask will not set to ffffff00 and broadcast will not set to 10.124.65.0

for the server IP of 10.124.65.75, How do I force the setting for netmask

and broadcast? -or- What am I doing wrong?

ORIGINAL DETAILS:

I am moving servers to a new LAN network and they are not coming up with the

netmask (ffffff00) and broadcast (10.124.65.0) values I want.

I am not using NIS or DNS.

My old IP was 159.45.41.127

The new IP is 10.124.65.11 and is set in file: /etc/hosts.

The file /etc/hostname.le0 matches my host's name.

The file /etc/defaultrouter matches up with entry in /etc/hosts and is my

new defaultrouter with IP of 10.124.65.1 and is pingable

The /etc/networks file looks like...

loopback 127

sun-ether 10.124.65 sunether ethernet localnet

sun-oldether 125 sunoldether

arpanet 10 arpa

ucb-ether 46 ucbether

The /etc/netmasks file looks like...

10.124 255.255.255.0

159.45 255.255.255.0

129.144 255.255.255.0

SUMMARY:

Did not know my ABC of network classes like I thought I did. All IP

addresses are 32 bit and have four octets. For SunOS 4.x, it thinks of life

in the pre-CIDR way.

Class A network IPs start wit a 0 bit = [1-126].x.x.x

loop back = 127.x.x.x

Class B network IPs start with bits 10 = [128-191].x.x.x

Class C network IPs start with bits 110 = [192-227].x.x.x

With CIDR, there are no such hard and fast rules. Instead subnet masks can

be applied to any IP address to create the size of network that is needed.

My misunderstanding was that my /etc/netmasks entry of "10.124" in the

pre-CIDR world (everything before

Solaris 2.6) was NOT a "network".

"10" is a network, "10.124" is not.

The file /etc/netmasks is used for subnetting classful networks.

I was moving from a class B network IP to a class A network IP and needed to

correctly name the new class A network in /etc/netmasks as first entry in

list to get sun to auto-set submask and broadcast to class C settings at

boot time (Correctly name = fully qualified network number "10.0.0.0"). This

is what I wanted and what I choose to do.

Also remember that /etc/netmasks is not consulted if YP is running. You'll

need to put this info on the YP server if that is the case. In my case YP

is not running.

Other suggestion was to manual set the netmask and broadcast address inside

of /etc/rc.local with something like...

ifconfig le0 inet 10.124.65.1 netmask 255.255.255.0 broadcast 10.124.65.0

-trailers

But I did not do this and I did not test this.

ABOUT BROADCAST...

Broadcast packets go to all nodes on the network. Typically, broadcast

packets are used for address resolution and network management applications.

Multicast packets are designed to be sent to a subset of nodes. SunOS and

Solaris will automatically set the sun's broadcast IP based off its IP and

its netmasks setting. However, the default setting for SunOS and for

Solaris is different.

SunOS = x.x.x.0

Solaris = x.x.x.255

THANK YOU:

I would like to thank the following for their responses,

Michael Connolly [MConnoll@ckcorp.com],

Mark Niell [Mark_Neill@csx.com],

Peter Wallis [Peter.Wallis@icl.co.za],

Darren Dunham [ddunham@taos.com],

Michael Glasgow [glasgow@bridgept.com],

Rick Kelly [rmk@toad.rmkhome.com],

David E. Schwarze [dxschwarze@link-us.net],

Chris 'Chipper' Chiapusio [chipper@llamas.net],

Dolores Capers [dcapers@netjets.com],

Parks Fields [parks@lanl.gov],

Thomas Knox [knoxth@cch.com],

Gavin Brennan [btigb@uis.doleta.gov],

Jerry Springer [jerry.springer@vcloud.com],

Shannon Wimberly [shannonw@isogen.com],

FROM:

Chris O'Neal <onealwc@agedwards.com>

When I am not computing in am WW1ing! Visit www.aerodrome.org to learn

more.

DATE:

10/24/2000

          

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[9962 byte] By [CodeProf.com] at [2007-12-25 11:31:00]