More than 254 users on an ethernet

More than 254 users on an ethernet

Post by Lee Goodm » Wed, 13 Nov 1996 04:00:00



Hello

I have a client that is converting from the routed LAN network (all
their users are behind a number of Novell server/routers)
to a flat network (all users are now on the same network). They
want to get rid of the Novell server/routers.

The client has a class B network, subnetted as a Class C
(255.255.255.0). So each site can have a max
of 254 hosts. The flat network will have
more than 254 hosts. I have been handling this
using secondary addresses. (zzz.yyyy.32.host, zzz.yyy.33.host,
zzz.yyy.34.host)
The problem is that the Cisco is now the single point of failure.
With the routed LAN, the cisco dying would cut off WAN access, now
with the flat network, the cisco dying would cut off one LAN subnet
from another.
Is there another way to do this? Either via hardware and/or software

Thanks

Lee Goodman

Lee Goodman
Information Access Center

 
 
 

More than 254 users on an ethernet

Post by Lawrence L. Baldwi » Wed, 13 Nov 1996 04:00:00


Why don't you choose a different subnetting scheme that would allow more
hosts/subnet (e.g. 255.255.240).

Also, you mention Novell servers--If you are using IPX protocol to talk
to the servers, then your IP subnetting will not affect Novell access.
Novell supports a nearly infinite number of clients per Novell
"subnet"--thus, you would not be depending on the Cisco to route Novell
LAN traffic.


> Hello

> I have a client that is converting from the routed LAN network (all
> their users are behind a number of Novell server/routers)
> to a flat network (all users are now on the same network). They
> want to get rid of the Novell server/routers.

> The client has a class B network, subnetted as a Class C
> (255.255.255.0). So each site can have a max
> of 254 hosts. The flat network will have
> more than 254 hosts. I have been handling this
> using secondary addresses. (zzz.yyyy.32.host, zzz.yyy.33.host,
> zzz.yyy.34.host)
> The problem is that the Cisco is now the single point of failure.
> With the routed LAN, the cisco dying would cut off WAN access, now
> with the flat network, the cisco dying would cut off one LAN subnet
> from another.
> Is there another way to do this? Either via hardware and/or software

> Thanks

> Lee Goodman

> Lee Goodman
> Information Access Center


--
-----------------------------------------------------------------------
Lawrence Baldwin                        System Management Tech., Inc.

Network Analysis Services               (718) 995-5542

 
 
 

More than 254 users on an ethernet

Post by Russell Mosema » Fri, 15 Nov 1996 04:00:00


:The client has a class B network, subnetted as a Class C
:(255.255.255.0). So each site can have a max
:of 254 hosts. The flat network will have
:more than 254 hosts. I have been handling this
:using secondary addresses. (zzz.yyyy.32.host, zzz.yyy.33.host,
:zzz.yyy.34.host)
:The problem is that the Cisco is now the single point of failure.
:With the routed LAN, the cisco dying would cut off WAN access, now
:with the flat network, the cisco dying would cut off one LAN subnet
:from another.
:Is there another way to do this? Either via hardware and/or software

   Sure.  Don't subnet.
--
Russell Mosemann     Concordia College      Voice: (402) 643-7445
Computing Center     Seward, NE 68434       Fax:   (402) 643-4073
"If you smell an odorless gas, it's probably carbon monoxide."
 - student answer on a chemistry test

 
 
 

More than 254 users on an ethernet

Post by Lee Goodm » Sat, 16 Nov 1996 04:00:00


I know that I could use a different subnet mask to make this work, but
that would be an admin nightmare for the IS staff that supports the
600+ users (currently they are masked as 255.255.255.0), we are
currently using a list of secondary addresses to support this.

The answer I was looking for would be a way to support
these users, but not have to make a lot of changes
to the users profiles
Looking for a hardware answer if possible
Maybe using a ethernet switch with internal routing and/or virtual
lans

Any help , suggestions or examples

Lee



>:The client has a class B network, subnetted as a Class C
>:(255.255.255.0). So each site can have a max
>:of 254 hosts. The flat network will have
>:more than 254 hosts. I have been handling this
>:using secondary addresses. (zzz.yyyy.32.host, zzz.yyy.33.host,
>:zzz.yyy.34.host)
>:The problem is that the Cisco is now the single point of failure.
>:With the routed LAN, the cisco dying would cut off WAN access, now
>:with the flat network, the cisco dying would cut off one LAN subnet
>:from another.
>:Is there another way to do this? Either via hardware and/or software
>   Sure.  Don't subnet.
>--
>Russell Mosemann     Concordia College      Voice: (402) 643-7445
>Computing Center     Seward, NE 68434       Fax:   (402) 643-4073
>"If you smell an odorless gas, it's probably carbon monoxide."
> - student answer on a chemistry test

Lee Goodman
Information Access Center

 
 
 

More than 254 users on an ethernet

Post by Russell Mosema » Sat, 16 Nov 1996 04:00:00



>I know that I could use a different subnet mask to make this work, but
>that would be an admin nightmare for the IS staff that supports the
>600+ users (currently they are masked as 255.255.255.0), we are
>currently using a list of secondary addresses to support this.

   I don't understand why this "would be an admin nightmare".  The
only thing that will change is the network mask and the broadcast
address.  Perhaps you think the changes will take a lot of work?  You
are using bootp and/or dhcp on all of those computers, aren't you?
That should take about all of 2 minutes to change 600+ hosts.  Sweet
dreams.
--
Russell Mosemann     Concordia College      Voice: (402) 643-7445
Computing Center     Seward, NE 68434       Fax:   (402) 643-4073
"St. Patrick was not Irish, Adolf Hitler was not German and Haagen-Dazs
 is nonsense syllables made up by an American ice cream maker."
 
 
 

More than 254 users on an ethernet

Post by Dustin Sallin » Tue, 19 Nov 1996 04:00:00



> I know that I could use a different subnet mask to make this work, but
> that would be an admin nightmare for the IS staff that supports the
> 600+ users (currently they are masked as 255.255.255.0), we are
> currently using a list of secondary addresses to support this.

        Your only solution is to subnet properly.  There isn't a limit
of only 254 nodes on ethernet, there's a limit of 254 nodes in a network
subnetted /24 (255.255.255.0) which is what you are doing.  If you had
two subnets of /24, they wouldn't be on the same network, but would be
reachable via the router.  I'm not sure what kind of solution you're
looking for wherein you subnet down to 254 addresses then try to use
600.  Seems a little odd to me.

Quote:> The answer I was looking for would be a way to support
> these users, but not have to make a lot of changes
> to the users profiles
> Looking for a hardware answer if possible
> Maybe using a ethernet switch with internal routing and/or virtual
> lans

        Unless I don't understand the problem correctly, it's not a
hardware issue.  You just can't tell it that you want to limit the
network to 254 nodes than try to use and have them talk locally.

dustin

 
 
 

More than 254 users on an ethernet

Post by Lee Goodm » Thu, 21 Nov 1996 04:00:00


The users is not using bootp/dhcp
They would have to change masks on all user machines



>>I know that I could use a different subnet mask to make this work, but
>>that would be an admin nightmare for the IS staff that supports the
>>600+ users (currently they are masked as 255.255.255.0), we are
>>currently using a list of secondary addresses to support this.
>   I don't understand why this "would be an admin nightmare".  The
>only thing that will change is the network mask and the broadcast
>address.  Perhaps you think the changes will take a lot of work?  You
>are using bootp and/or dhcp on all of those computers, aren't you?
>That should take about all of 2 minutes to change 600+ hosts.  Sweet
>dreams.
>--
>Russell Mosemann     Concordia College      Voice: (402) 643-7445
>Computing Center     Seward, NE 68434       Fax:   (402) 643-4073
>"St. Patrick was not Irish, Adolf Hitler was not German and Haagen-Dazs
> is nonsense syllables made up by an American ice cream maker."

Lee Goodman
Information Access Center

 
 
 

1. Class C network with 255.255.254.0 subnet mask

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My internet provider gave me a block of 32 class C networks.I'd like to
have a 512 nodes network, may I join 2 of my class C networks with a
9-bit subnet mask ?

I mean something like:

interface ethernet 0
ip address 193.145.60.1 255.255.254.0

so the IP network would be from 193.145.60.1 to 193.145.61.255

Routing protocol: EIGRP.

Thanks in advance

Marc Vives
Network Manager
Universitat Pompeu Fabra

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