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?
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$2v1.13762@newssvr14.news.prodigy. 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.
On Thu, 26 Jul 2007 08:58:35 -0700, SparkyGuy
<SparkyGuy@mumcrank.ck> 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 :-)
"SparkyGuy" <SparkyGuy@mumcrank.ck> wrote in message
news:0001HW.C2CE12BB013B0063F01826C8@news.sf.sbcgl 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.
>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.
>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.
In article <72tha3lt6jvdiignb77vf09f6l2ofihn7j@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:
> SparkyGuy <SparkyGuy@mumcrank.ck> 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.
Good guess. It's exactly ten, and that's how many I have set on my own
office LAN.
--
Rich Seifert Networks and Communications Consulting
21885 Bear Creek Way
(408) 395-5700 Los Gatos, CA 95033
(408) 228-0803 FAX
"SparkyGuy" <SparkyGuy@mumcrank.ck> wrote in message
news:0001HW.C2CE3B3701447D7DF01826C8@news.sf.sbcgl obal.net...
>> - if you want to use the DMZ approach, then the address of the computer
>> in
>> question must be static.
>
> What's "DMZ"?
It means 'demilitarized zone'.
The concept is that the router will take specific internet requests that it
receives,
such as port 80 (web servers) and forward these requests to one specific
machine.
This way you can run a web server on that one machine, and make it open
to the public without placing your whole network at risk.
There is some disagreement as to how secure an arrangement this provides,
and it
is only of use if you want a computer to be 'open' to the whole internet.
I use it for testing server configurations before I put them on the actual
web server here.
The actual web server has its own ip address, and is therefore totally
isolated from
the LAN here.
>
>> - 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)
>
As far as the client computer is concerned, static means that the computer
has
an address specified in its network setting and DHCP client is turned off.
If DCHP client is turned on, the client does not care (or even know about)
how the router decides what IP address to assign.
In article <gebqi.7036$_d2.4748@pd7urf3no>,
Stuart Miller <stuart_miller@shaw.ca> wrote:
>"SparkyGuy" <SparkyGuy@mumcrank.ck> wrote in message
>news:0001HW.C2CE3B3701447D7DF01826C8@news.sf.sbcg lobal.net...
>> What's "DMZ"?
>
>It means 'demilitarized zone'.
>The concept is that the router will take specific internet requests that it
>receives,
>such as port 80 (web servers) and forward these requests to one specific
>machine.
> This way you can run a web server on that one machine, and make it open
>to the public without placing your whole network at risk.
I would have described a DMZ as a network (not limited to only one
machine) segment outside the firewall protecting your internal LAN.
The main point being if your web/ftp/whatever server is compromised
your internal LAN is still protected.
Jeff Liebermann wrote:
> SparkyGuy <SparkyGuy@mumcrank.ck> 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.
>
The second big downside is if "you're it" and this cheap router dies, what happens to the office. The more things you put in it the more fragile your office is. These cheaper routers are disposable so plan for it. When I put things like this into a small business I made them buy 2 of the EXACT same model and loaded the running config into the 2nd one. Then if the router died I could talk them through swapping it out from the beach. As that would invariably be where I would be at when it did die.
:)
And if the OP is smart they'll test the swap so you know if they need to do things like power down the cable modem for 5 minutes to make it accept the Mac change or maybe you clone the MAC in the 2nd router to make it match the first. And so on.
DLR wrote:
> When I put things like this into a small business I made them buy 2
> of the EXACT same model and loaded the running config into the 2nd one.
> Then if the router died I could talk them through swapping it out from
> the beach.
Not a bad idea.
> As that would invariably be where I would be at when it did die.
>Jeff Liebermann wrote:
>> SparkyGuy <SparkyGuy@mumcrank.ck> 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.
>The second big downside is if "you're it" and this cheap router dies,
>what happens to the office. The more things you put in it the more fragile
>your office is. These cheaper routers are disposable so plan for it.
>When I put things like this into a small business I made them
>buy 2 of the EXACT same model and loaded the running config into the
>2nd one. Then if the router died I could talk them through swapping
>it out from the beach. As that would invariably be where I would be
>at when it did die.
Good point. My small customers are so cheap and failures are so few,
that I don't think I could justify the expense. What I do is set the
lease time expiration time to something like a week. I can run for
that long until I drag in a replacement.
<http://www.samspublishing.com/articles/article.asp?p=30874&seqNum=3&rl=1>
Key hardware, such as print servers, modem servers, and routers all
get static IP's that are not dependent on the static DHCP in the
router.
I also save a backup of the router configuration but rarely use it.
The printed copy is more useful. That's because if the router needs
replacement, it's probably old and ancient. I don't want to be
replacing an 802.11b only wireless router with another one that won't
do 802.11g or better. So, I use the oportunity to do an upgrade,
which makes the backups somewhat useless.
>And if the OP is smart they'll test the swap so you know if they need
>to do things like power down the cable modem for 5 minutes to make
>it accept the Mac change or maybe you clone the MAC in the 2nd router
>to make it match the first. And so on.
>
>David Ross
That depends on the size of the company. My medium size companies
tend to have Cisco routers with failover setup on primary and backup
DHCP servers.
<http://www.cisco.com/en/US/docs/net_mgmt/network_registrar/6.1.1/user/guide/16Failov.html>
Same with Sonicwall (SonicOS) routers that support DHCP failover
(TZ170 mostly).
For small companies, that's overkill. I usually end up walking the
affected people through setting a temporary static IP on their desktop
so they can continue working. I carry spare routers in my office and
in my truck and can usually do a same day replacement. The hard part
is finding the paperwork and passwords, which unfortunately my
customers deem to be my job, not theirs.
Jeff Liebermann wrote:
> DLR <news23@raleighthings.com> hath wroth:
>
>> Jeff Liebermann wrote:
>>> SparkyGuy <SparkyGuy@mumcrank.ck> 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.
>
>> The second big downside is if "you're it" and this cheap router dies,
>> what happens to the office. The more things you put in it the more fragile
>> your office is. These cheaper routers are disposable so plan for it.
>> When I put things like this into a small business I made them
>> buy 2 of the EXACT same model and loaded the running config into the
>> 2nd one. Then if the router died I could talk them through swapping
>> it out from the beach. As that would invariably be where I would be
>> at when it did die.
>
> Good point. My small customers are so cheap and failures are so few,
> that I don't think I could justify the expense. What I do is set the
From the original post:
> Netgear RP614 router.
These things are $60 at Frys web site.
I just tell folks, when lightning strikes nearby this is the most likely thing to go. Pay $60 now and 10 minutes of my time or $200 or more when it dies and you want me there NOW!
"DLR" <news23@raleighthings.com> wrote in message
news:37748$46ab4df2$d1aa8d95$19374@PORTBRIDGE.COM. ..
> These cheaper routers are disposable so plan for it.
I have an wireless router here (DLink DI-764, 802.11a/b) that has been
running 24/7/365 since 2002. The "Static DHCP" table has 23 entries. Yep,
they do add up quickly. I no longer use the radios in the DI-764 (even
removed the antennas), it is simply being used as a wired router. (Have a
DWL-7100AP 802.11a/g/b WAP attached to it now.) I wish the DI-764 WOULD die
so I would have an excuse to replace it with a nice wired router! I'm a
cheap bastard that can't justify replacing it as long as it is remains
working.
> *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).
This is incorrect, or at the very least, incomplete. You can setup DHCP to
reserve addresses based on MAC address. The same hardware will get the same
DHCP lease every time. Yes, if you change the hardware in the computer it
will require configuring a new lease reservation on the DHCP server. But
you'd also have to manually reconfigure it if it was static.
When using a Windows Active Directory domain the DHCP server is integrated
with DNS. So the name of the Windows machine can be automatically
propogated into the internal DNS. It's also easy to use the GUI to check on
what addresses are allocated. Some text-based DHCP servers do not make it
this easy and also wonn't integrate with DNS.
But in either case it's a simple matter of speaking with the user and asking
them to run the command "ipconfig" or "ifconfig" if they're not on windows
box (linux, etc...) to get the unit's current IP address. So it's not like
you have to lay hands on it directly.
> *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, incorrect if the device CAN use DHCP. Setup a lease for that
hardware MAC (Media Access Control, not Macintosh) address and it will
always have the same one. Most devices that do not have a user interface
(no buttons, no screens) will default to using DHCP out of the box.
Manually changing this to something else only complicates your support
efforts if/WHEN you have to replace the unit. Otherwise you just read the
MAC address off the back of the box when installing it and setup a lease for
it.
I do find it useful to setup the DHCP ranges starting above 64 or so. Only
to lease the lower addresses free for devices that actually DO require
static ones.
> The main point being if your web/ftp/whatever server is compromised
> your internal LAN is still protected.
Unfortunately too many folks configure their firewall to let DMZ devices get
into the internal network. Thus compromising a DMZ device often provides an
*easier* attack vector than taking the firewall head-on. If you're going to
use a DMZ setup, make sure that whatever firewall rules exist for it (and
programs running on it) have VERY strict controls on where it can connect
internally (if at all).
> But in either case it's a simple matter of speaking with the user and asking
> them to run the command "ipconfig" or "ifconfig" if they're not on windows
> box (linux, etc...) to get the unit's current IP address. So it's not like
> you have to lay hands on it directly.
"Reserved" IP vs. manually-assigned? 
Linear Mode
