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No-NAT help



 
 
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  #1  
Old July 9th 03, 05:44 PM posted to uk.telecom.broadband
marty
external usenet poster
 
Posts: 3
Default No-NAT help

I'm having some problems understaning how a No-NAT 5 package works...

With Dynamic, I assume your IP address potentially changes every time your
turn the power off in your ADSL router.

With Static, I assume your IP address remains as is for the lifetime of your
ISP account.

I'm confused with No-NAT however. Say, for example, I got a No-NAT 5
service - I get 5 IP addresses. The IP address for the router is dynamic -
is that correct? If so, why do the subnet addresses not need to change each
time the router IP address changes. Does the subnet mask determine this? I'm
completely confused about No-NAT so any help would be greatly appreciated!

TIA


  #2  
Old July 9th 03, 05:54 PM posted to uk.telecom.broadband
marty
external usenet poster
 
Posts: 3
Default No-NAT help


"Chris" wrote in message
. ..

"marty" [email protected]^n^t^l^w^o^r^l^d^.^c^o^m^ wrote in message
...
I'm having some problems understaning how a No-NAT 5 package works...

With Dynamic, I assume your IP address potentially changes every time

your
turn the power off in your ADSL router.

With Static, I assume your IP address remains as is for the lifetime of

your
ISP account.

I'm confused with No-NAT however. Say, for example, I got a No-NAT 5
service - I get 5 IP addresses. The IP address for the router is

dynamic -
is that correct? If so, why do the subnet addresses not need to change

each
time the router IP address changes. Does the subnet mask determine this?

I'm
completely confused about No-NAT so any help would be greatly

appreciated!

TIA


With a no NAT service you get a /29 IP range that is statically assigned

to
the ethernet side of your router. This can then be connected to a firewall
which should either provide NAT for your internal LAN or proxy services.

How the ATM side of the router is set up depends on who is delivering the
service. Ours has a fixed IP address on the outside to talk to the BRAS

and
then the /29 applied to the ethernet to talk to the firewall and route the
customers IP range.

Chris.


Thanks Chris.

Do you actually get a range of IP addresses e.g. xxx.xxx.xxx.000 to
xxx.xxx.xxx.028 of do you get a base address (xxx.xxx.xxx.000) which, along
with your subnet size, is used to determine the complete range?


  #3  
Old July 9th 03, 06:03 PM posted to uk.telecom.broadband
[email protected] writeme.com
external usenet poster
 
Posts: 85
Default No-NAT help

On Wed, 9 Jul 2003 16:44:05 +0100, "marty"
[email protected]^n^t^l^w^o^r^l^d^.^c^o^m^ wrote:

I'm having some problems understaning how a No-NAT 5 package works...

With Dynamic, I assume your IP address potentially changes every time your
turn the power off in your ADSL router.

You seem confused between static IP and dynamic IP and NAT. NAT has
nothing to with whether you get a static or dynamic IP from your ISP.

Andrew.
  #4  
Old July 9th 03, 11:02 PM posted to uk.telecom.broadband
Chris
external usenet poster
 
Posts: 5
Default No-NAT help


"marty" [email protected]^n^t^l^w^o^r^l^d^.^c^o^m^ wrote in message
...

"Chris" wrote in message
. ..

"marty" [email protected]^n^t^l^w^o^r^l^d^.^c^o^m^ wrote in message
...
I'm having some problems understaning how a No-NAT 5 package works...

With Dynamic, I assume your IP address potentially changes every time

your
turn the power off in your ADSL router.

With Static, I assume your IP address remains as is for the lifetime

of
your
ISP account.

I'm confused with No-NAT however. Say, for example, I got a No-NAT 5
service - I get 5 IP addresses. The IP address for the router is

dynamic -
is that correct? If so, why do the subnet addresses not need to change

each
time the router IP address changes. Does the subnet mask determine

this?
I'm
completely confused about No-NAT so any help would be greatly

appreciated!

TIA


With a no NAT service you get a /29 IP range that is statically assigned

to
the ethernet side of your router. This can then be connected to a

firewall
which should either provide NAT for your internal LAN or proxy services.

How the ATM side of the router is set up depends on who is delivering

the
service. Ours has a fixed IP address on the outside to talk to the BRAS

and
then the /29 applied to the ethernet to talk to the firewall and route

the
customers IP range.

Chris.


Thanks Chris.

Do you actually get a range of IP addresses e.g. xxx.xxx.xxx.000 to
xxx.xxx.xxx.028 of do you get a base address (xxx.xxx.xxx.000) which,

along
with your subnet size, is used to determine the complete range?



You are assigned a network address along with a subnet mask which you can
then use to work out which is your last usable address and which is the
broadcast address.

Chris.



  #5  
Old July 10th 03, 01:43 PM posted to uk.telecom.broadband
Stroller
external usenet poster
 
Posts: 80
Default No-NAT help

"marty" [email protected]^n^t^l^w^o^r^l^d^.^c^o^m^ wrote in message ...
"Chris" wrote in message
. ..

With a no NAT service you get a /29 IP range that is statically assigned

to
the ethernet side of your router. This can then be connected to a firewall
which should either provide NAT for your internal LAN or proxy services.

How the ATM side of the router is set up depends on who is delivering the
service. Ours has a fixed IP address on the outside to talk to the BRAS

and
then the /29 applied to the ethernet to talk to the firewall and route the
customers IP range.



Do you actually get a range of IP addresses e.g. xxx.xxx.xxx.000 to
xxx.xxx.xxx.028 of do you get a base address (xxx.xxx.xxx.000) which, along
with your subnet size, is used to determine the complete range?


Well, in fact these two things are synonymous - it doesn't matter if
you describe the integers in the range of one to five inclusive as {1,
...., 5} or as {1, 2, 3, 4, 5}.

I think you may be misunderstanding the term "/29" subnet, however.

Subnet masks are a way of separating our computers into groups - they
can tell from the subnet mask we give them whether we've placed a
router between them and any other given IP address.

IP addresses are 32-bit numbers, so the IP address 10.0.0.5 can be
expressed as:
00001010.00000000.00000000.00000101 (except we wouldn't
use the dots)

Subnet masks are consequently also 32-bit numbers, but they always
fill up from the left to the right, so for the above IP address the
following subnet masks would all be equally valid (depending upon the
arrangements of computers on the LAN):
255.0.0.0 = 11111111.00000000.00000000.00000000
255.255.0.0 = 11111111.11111111.00000000.00000000
255.255.128.0 = 11111111.11111111.11110000.00000000

The following subnet mask, however, is NOT EVER valid:
255.0.0.255 = 11111111.00000000.00000000.11111111
Because it has a 1 to the right of a 0.

Again, please note the dots are used here for illustrative purposes
only, and are never used in the PC's internal representation of the
IP/mask. In fact, when you enter your IP address of 10.0.0.5 the PC
will converted it to 00001010000000000000000000000101 as soon as you
press the OK button.

Anyway, because we know that a subnet mask will always have some
number of 1s on the left, and the remaining bits will be 0 to the end
of the mask, we can "compress" subnet masks a bit like a gif when
writing shorthand:
255.0.0.0 = 11111111000000000000000000000000 is called "\8"
(because it has 8 ones).
255.255.0.0 = 11111111111111110000000000000000 is called "\16"
255.255.128.0 = 11111111111111111111000000000000 is called "\20"
And so on...

Consequently, you can see that "\29" means a subnet mask of 29 1s and
3 0s, thus:
11111111111111111111111111111000 or 255.255.255.248

Now, since each IP address has to be unique within the subnet, this
means that you can only have as many computers in your subnet as there
are "remaindered" bits within the subnet mask. Consequently in a
255.255.255.0 subnet you can have 255 PCs (less one or two for special
IPs) and in a 255.0.0.0 subnet you can have (255 x 255 x 255 = )
approximately 16,500,000 machines.

In a 255.255.255.128 subnet you only have room for 128 unique IP
addresses, and in your "/29" subnet you only have room for about
(binary 111 = ) 7 IPs. As I recall, one of these is used for the
broadcast address (used, for instance, by M$ networking to call out to
all the PCs in the LAN to get them to report what to show in network
neighbourhood), and one for the network identifier. This leaves you
with your 5 usable IPs in a /27 subnet.

I hope this is of interest to someone,

Stroller.
  #6  
Old July 10th 03, 06:47 PM posted to uk.telecom.broadband
Chris
external usenet poster
 
Posts: 5
Default No-NAT help

This leaves you
with your 5 usable IPs in a /27 subnet.

I hope this is of interest to someone,

Stroller.


Ahm ... I guess that you meant /29. Don't confuse people!!

To clarify ..

/30 4 address, one network, one broadcast, two usable
/29 8 addresses, one network, one broadcast, six usable
/28 16 addresses, one network, one broadcast, fourteen usable.

..... and so on!

;-)


  #7  
Old July 10th 03, 07:07 PM posted to uk.telecom.broadband
marty
external usenet poster
 
Posts: 3
Default No-NAT help


"Chris" wrote in message
. ..
This leaves you
with your 5 usable IPs in a /27 subnet.

I hope this is of interest to someone,

Stroller.


Ahm ... I guess that you meant /29. Don't confuse people!!

To clarify ..

/30 4 address, one network, one broadcast, two usable
/29 8 addresses, one network, one broadcast, six usable
/28 16 addresses, one network, one broadcast, fourteen usable.

.... and so on!

;-)


Cheers for that guys - it was a great help.


  #8  
Old July 11th 03, 02:01 PM posted to uk.telecom.broadband
Stroller
external usenet poster
 
Posts: 80
Default No-NAT help

"Chris" wrote in message ...
This leaves you
with your 5 usable IPs in a /27 subnet.

I hope this is of interest to someone,

Stroller.


Ahm ... I guess that you meant /29. Don't confuse people!!

To clarify ..

/30 4 address, one network, one broadcast, two usable
/29 8 addresses, one network, one broadcast, six usable
/28 16 addresses, one network, one broadcast, fourteen usable.

.... and so on!


Whups! My bad. I'll blame the keyboard for that typo.
Now why couldn't I have been that succinct in the first place..?

Stroller.
 




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