From: James P. Egan
Subject: Subnetting: Networking One Piece at a Time.
I read with interest the subject article and found it
very well written
and thorough. I did, however, find what I believe is
an error. On
page 16, the table showing Network, Broadcast, and Netmask
different netmasks for each subnet. I think the netmask
the same for each subnet and have a value of 255.255.255.192.
James P. Egan
Integrated Architectures, Inc.
Milford, MA 01757
Chris Hare responds to this and other messages:
A part of my article, "Subnetting: Networking One
at a Time," in the January/February 1995 issue
of Sys Admin, unfortunately
created a bit of confusion in one area. On page 12,
in the section
entitled "Changing the Network," I should
have stated that
splitting a class C network into 8 divisions will will
give you 6
subnets when the restrictions for RFC 950 are applied.
In addition, I have received two questions from readers
concerning the article. The first one was concerned
with the broadcast
The broadcast address for each subnet will be different
in order to broadcast only on the hosts in that subnet.
delicious.apple.bite 18.104.22.168 Subnet 1
macintosh.apple.bite 22.214.171.124 Subnet 1
spartan.apple.bite 126.96.36.199 Subnet 3
If you use a common broadcast address for all of these
machines, then the possibility exists that they could
unneeded packets. Normally, the broadcast address would
be used only
to broadcast to the hosts on the same portion of the
is why the broadcast addresses are different.
It is not incorrect to use the typical Class C broadcast
address of 188.8.131.52, but it is perhaps less efficient.
the table on page 16 is incorrect.
The second issue had to do with the netmask and, again,
entailed a correction to the table on page 16. Once
the Class C network
has been split up, the same netmask is typically used
on all portions.
(You can however, in some situations, use different
the same address space!) For the sample network that
the netmask is actually 255.255.255.224. This is derived
7. The sample network I created had eight divisions,
and six usable
subnets. This means that the network portion of the
address is 1110
0000 binary, or 224 decimal. This makes the netmask
for all of the
Given these two points, the table on page 16 should
Network Broadcast Netmask
N.O.P.32 N.O.P.63 255.255.255.224
N.O.P.64 N.O.P.95 255.255.255.224
N.O.P.96 N.O.P.127 255.255.255.224
N.O.P.128 N.O.P.159 255.255.255.224
N.O.P.160 N.O.P.191 255.255.255.224
N.O.P.192 N.O.P.223 255.255.255.224
I hope that this will help clarify any confusion that
inadvertently created. I thank all of the people who
comments on this article. I appreciate the feedback.
Chris Hare, R.G.R., A.C.E.
Subject: Solaris Performance Question
Does anyone have a detailed explanation as to why Solaris
2.3 is no
faster or even slower than SunOs 4.1.3?
A lot of us are asking this question but have no clear
other than "CPU overhead for Security processes"
code that has not been optimized" -- pretty vague
We have a Sparc LX w/16mb RAM w/SunOS 4.1.3 running
next to a Sparc
1000 w/128mb RAM w/Sol 2.3 and the Login process, and
performance is slower on the Sparc 1000 than on the
LX. We understand
Sol2.3 is more complex and not as mature as 4.1.3, but
a little more
detail on what these performance problems are due to
and when they
might be fixed would be helpful (Sun, are you listening?).
Are others experiencing the same performance gap? Does
Sol 2.4 solve