One thing I want to mentioned is that Mobile IP can solve your problem. You
can move to another place without changing your IP address, but still keep
connection. However, you must configure both floor 1 and floor 2 router to
support Foreign agent and home agent function. Your computer client also
support mobile IP registration.
- Original Message -
From: Priscilla Oppenheimer
To:
Sent: Thursday, January 09, 2003 4:58 PM
Subject: RE: Subnet question [7:60711]
Larry Letterman wrote:
thats pris's job hereif she writes enough detailed
answers we dont have to buy her books...:)
Oh no!
By the way, the only nicknames that are supported are Cilla, PO, (and Cil,
if you are Chuck.) Nicknames that map to sissified have been deprecated.
The preferred name is my canonical name, Priscilla. :-)
Larry Letterman
Network Engineer
San Jose Transport
Cisco Systems Inc.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf Of
Tamhankar, Nitin
Sent: Thursday, January 09, 2003 11:18 AM
To: [EMAIL PROTECTED]
Subject: RE: Subnet question [7:60711]
Thank you very much for taking pains to right such a detailed
explanation.
Thank you all for your answers they were very helpful.
Thanks
Nitin
-Original Message-
From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]]
Sent: Thursday, January 09, 2003 12:36 PM
To: [EMAIL PROTECTED]
Subject: RE: Subnet question [7:60711]
You may not need virtual LANs. Real LANs solve the problem.
:-) This is a
classic case of subnetting.
With DHCP, the client should get the right address when it
broadcasts after
it moves, so there's no issue.
Leaving DHCP out of the picture, the need to ensure that a
moved
node can't
communicate is met simply by the way IP works.
Assume there's a client with this config:
address = 100.10.1.100
subnet mask = 255.255.255.0
default gateway = 100.10.1.1
Assume the client is physically sitting on the 100.10.2.0/24
network. When
it wants to send to nodes on the 100.10.1.0 network, it will
compare its
address with the destination address, assume it's on the same
subnet, and
send an ARP broadcast. The ARP broadcast won't reach the
destination though,
which is on a different LAN, so it won't work.
(Make sure the router isn't configured for Proxy ARP. But
even with Proxy
ARP, communication won't work. With Proxy ARP, the router
could respond on
behalf of the destination on the 100.10.1.0 network. However
that host
wouldn't be able to respond because it would assume that
100.10.1.1 is
local.)
Assume the client wishes to reach devices on the 100.10.2.0
or 100.10.3.0
network. It will compare its address with the destination
address
and decide
that it's not on the same subnet, so it needs to send to the
default
gateway. It will send a broadcast for the default gateway,
which
won't work
because 10.10.1.1 is on a different LAN. Once again make sure
Proxy ARP is
disabled. I'll leave it to the reader to figure out what
would happen in
this case if Proxy ARP were enabled. :-)
The question of VLANs versus real LANs requires more info.
How many router
ports to you have? Is each router port a subnet? Or do you
plan to have
multiple subnets out one router port, in which case you need
VLANs and
inter-VLAN routing on the router.
___
Priscilla Oppenheimer
www.troubleshootingnetworks.com
www.priscilla.com
Nathan Nakao wrote:
I'd probably use VLAN's.
Conf t
Int vlan 101
Int vlan 102
Int vlan 103
Then setup the DHCP to assign IP addresses accordingly.
Once that is done. Set the vlans to 101 for first floor, 102
for second
floor, and 103 for third floor.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
On
Behalf Of
Tamhankar, Nitin
Sent: Thursday, January 09, 2003 8:40 AM
To: [EMAIL PROTECTED]
Subject: Subnet question [7:60711]
This might be a very elementary question for some of you
guys
but I
would appreciate the answer.
If an office which has 3 different floors and has Cisco
routers
and
catalyst switches and windows environment. We need to
configure
it in
such a way that each floor is on its own subnet for example
floor1 100.10.1.0
floor2 100.10.2.0
floor3 100.10.3.0
Also if a computer which has IP address in subnet
100.10.1.0 is
moved
from floor 1 to floor 2, it should not communicate with the
network
unless its IP address is changed to one in 100.10.2.0
subnet.
How it can be accomplished?
Thank you
Nitin
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