"Reserved" IP vs. manually-assigned?

Netgear RP614 router.

Under the LAN configuration menu there are, among others, options for DHCP,
and Manually-assigned IP addresses. Under DHCP there is also a table for
reserving IP addresses. This feature allows you to use DHCP to dynamically
assign addresses except that for each MAC address you specify, the router
will assign a particular IP (specified by you).

Is there any difference between reserving an IP address under DHCP, and
manually assigning one?

Thanks,
Sparky

SparkyGuy wrote:
> Netgear RP614 router.
>
> Under the LAN configuration menu there are, among others, options for DHCP,
> and Manually-assigned IP addresses. Under DHCP there is also a table for
> reserving IP addresses. This feature allows you to use DHCP to dynamically
> assign addresses except that for each MAC address you specify, the router
> will assign a particular IP (specified by you).

I'm not acquainted with the Netgear setup, but typically routers will give
you an option of where you want to start the dynamic DHCP IP pool addresses.

> Is there any difference between reserving an IP address under DHCP, and
> manually assigning one?

The most significant difference is how you want to uniquely manage you
network computers, otherwise there is no significant difference between the
two methods. Either method will give you a perfectly functioal network.

Therefore, the way I do it may be best for my applications, but not for
someone else's.

Typically I set up networks to start the DHCP pool at 100, as in
192.168.0.100. That allows me 155 computers that are "plug and play" so to
speak when they plug in their computers to the network. The 0.100 is an
easy number to remember, I could have just as easily used 0.10

Pros and cons....

*DHCP is easy to manage.* You don't have to keep a text file on hand to
keep track of your IP addresses in the network to avoid assigning a
duplicate IP to another computer and end up with IP conflict error
messages. A static IP network requires rigid tracking of the IP addresses
you've assigned. Static IP's are easy to manage on a SMALL network. In my
office I have less than a dozen computers and its easy to remember their
address.

*DHCP is easy to connect to a foreign network.* When I'm at a client's
site, I set my laptop to DHCP and let it connect to the network. Then I
look at my connection status and can find my IP, the subnet, and the
gateway address. Setting your laptop with a static IP can often be a hit
and miss operation getting connected.

*DHCP requires you to physically go and find a computer's IP address.* If
you want to ping or remote into a computer, you have to go and finds it's
address. With a static IP, you can ping into the name of the computer (if
you have a text file of all the computer names).

*Some applications can only use a static IP* Lets say you have a server,
video camera, or need to remote into a computer on your LAN from the
outside. You need to set Network Address Translation (NAT) in your DSL
modem and/or router. If you computers are set to DHCP, your computers'
addresses may be unpredictable.

Again, this is only my unique suggestions off the top of my head. Others
may have different suggestions and input for the pros and cons.

"DTC" <no_spam@move_along_folks.foob> wrote in message
news:mR4qi.28962$(E-Mail Removed). net...
> SparkyGuy wrote:
>> Netgear RP614 router. Under the LAN configuration menu there are, among
>> others, options for DHCP, and Manually-assigned IP addresses. Under DHCP
>> there is also a table for reserving IP addresses. This feature allows you
>> to use DHCP to dynamically assign addresses except that for each MAC
>> address you specify, the router will assign a particular IP (specified by
>> you).
>
> I'm not acquainted with the Netgear setup, but typically routers will give
> you an option of where you want to start the dynamic DHCP IP pool
> addresses.
>
>> Is there any difference between reserving an IP address under DHCP, and
>> manually assigning one?
>
> The most significant difference is how you want to uniquely manage you
> network computers, otherwise there is no significant difference between
> the two methods. Either method will give you a perfectly functioal
> network.
>
> Therefore, the way I do it may be best for my applications, but not for
> someone else's.
>
> Typically I set up networks to start the DHCP pool at 100, as in
> 192.168.0.100. That allows me 155 computers that are "plug and play" so to
> speak when they plug in their computers to the network. The 0.100 is an
> easy number to remember, I could have just as easily used 0.10
>
> Pros and cons....
>
> *DHCP is easy to manage.* You don't have to keep a text file on hand to
> keep track of your IP addresses in the network to avoid assigning a
> duplicate IP to another computer and end up with IP conflict error
> messages. A static IP network requires rigid tracking of the IP addresses
> you've assigned. Static IP's are easy to manage on a SMALL network. In my
> office I have less than a dozen computers and its easy to remember their
> address.
>
> *DHCP is easy to connect to a foreign network.* When I'm at a client's
> site, I set my laptop to DHCP and let it connect to the network. Then I
> look at my connection status and can find my IP, the subnet, and the
> gateway address. Setting your laptop with a static IP can often be a hit
> and miss operation getting connected.
>
> *DHCP requires you to physically go and find a computer's IP address.* If
> you want to ping or remote into a computer, you have to go and finds it's
> address. With a static IP, you can ping into the name of the computer (if
> you have a text file of all the computer names).
>
> *Some applications can only use a static IP* Lets say you have a server,
> video camera, or need to remote into a computer on your LAN from the
> outside. You need to set Network Address Translation (NAT) in your DSL
> modem and/or router. If you computers are set to DHCP, your computers'
> addresses may be unpredictable.
>
> Again, this is only my unique suggestions off the top of my head. Others
> may have different suggestions and input for the pros and cons.
>
>
I use the same concept here.

Desktop machines are static assigned, under 100, portable devices such as
the 3 laptops that come and go here are done by DHCP, over 100.

Some other considerations

- some network games require you to specify the ip address of the other
players to connect with.

- some network monitoring utilities are inconsistent, they find only dhcp
addresses, or find only static accdrsses, some find both.

- on some routers you can specify that the router will assign dynamically a
specific IP address to a specific MAC address.

- if you want to use the DMZ approach, then the address of the computer in
question must be static.

- print servers or shared printers seem to prefer a static IP address for
the computer they are attached to.

Stuart

On Thu, 26 Jul 2007 08:58:35 -0700, SparkyGuy
<(E-Mail Removed)> wrote:

>Netgear RP614 router.
>
>Under the LAN configuration menu there are, among others, options for DHCP,
>and Manually-assigned IP addresses. Under DHCP there is also a table for
>reserving IP addresses. This feature allows you to use DHCP to dynamically
>assign addresses except that for each MAC address you specify, the router
>will assign a particular IP (specified by you).
>
>Is there any difference between reserving an IP address under DHCP, and
>manually assigning one?

Yes. If you instruct your DHCP server to issue 'static'
addresses, you still get all the benefits of using DHCP.

If you decide to assign static addresses, you'll need to visit
all hosts if you want to change a simple thing like the DNS
server :-)

--
Kind regards,
Gerard Bok

"SparkyGuy" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) obal.net...
> Netgear RP614 router.
>
> Under the LAN configuration menu there are, among others, options for
> DHCP,
> and Manually-assigned IP addresses. Under DHCP there is also a table for
> reserving IP addresses. This feature allows you to use DHCP to dynamically
> assign addresses except that for each MAC address you specify, the router
> will assign a particular IP (specified by you).

I use it. DLink calls it "Static DHCP", but is the same thing.

> Is there any difference between reserving an IP address under DHCP, and
> manually assigning one?

Both methods achieve the same thing, but I think it is simpler just to have
the router give out IP addresses than to statically configure every
client -- especially with mobile devices.

SparkyGuy <(E-Mail Removed)> hath wroth:

>Netgear RP614 router.
>
>Under the LAN configuration menu there are, among others, options for DHCP,
>and Manually-assigned IP addresses. Under DHCP there is also a table for
>reserving IP addresses. This feature allows you to use DHCP to dynamically
>assign addresses except that for each MAC address you specify, the router
>will assign a particular IP (specified by you).
>
>Is there any difference between reserving an IP address under DHCP, and
>manually assigning one?

Yes.

Manually assigning the IP is done at the client computer. It should
be assigned outside the DHCP address range of the router. The problem
with this arrangement is that if the computer is moved around (as in a
laptop) it may need to be setup of other configurations at other
locations. There are tricks and utilities to do this, but it's
generally best to leave portables set to DHCP.

Pre-assigned IP (also known as static DHCP) is done in the router,
where the client is setup for DHCP. Everything is managed at the
router. This is good enough for port forwarding, which requires a
target computer that doesn't change IP addresses.

I usually prefer pre-assigned DHCP in the router as everything is
centrally managed.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

> Yes. If you instruct your DHCP server to issue 'static'
> addresses, you still get all the benefits of using DHCP.

Sounds like all good news.

> If you decide to assign static addresses, you'll need to visit
> all hosts if you want to change a simple thing like the DNS
> server :-)

I've already entered the DNS server numbers in each computer that is getting
assigned a "fixed" address by DHCP.

So there's no down-side to the "DHCP-assigned-fixed-IP" approach?

Thanks,
Sparky

> - if you want to use the DMZ approach, then the address of the computer in
> question must be static.

What's "DMZ"?

> - print servers or shared printers seem to prefer a static IP address for
> the computer they are attached to.

Does "static IP address" include those "fixed" addresses assigned by DHCP
(assigned per MAC address -- see my original post)

Thanks,
Sparky

> I usually prefer pre-assigned DHCP in the router as everything is
> centrally managed.

Your word is good enough for me, Jeff.

Thanks!

Sparky

SparkyGuy <(E-Mail Removed)> hath wroth:

>So there's no down-side to the "DHCP-assigned-fixed-IP" approach?

There's always a down side to any good idea. The big one is most
cheap routers only have room for a few devices in the "static DHCP"
table. My guess is the RP-614 can only handle about 10 devices. That
may seem like enough but I've run out of table space with systems full
of IP cameras, print servers, and IP managed devices. By the time I'm
done assigning "static DHCP" or "static Lease" entries for these,
there's no room for the PC's.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558