device list

Here's a question:

How can a single wireless device (a laptop) on a LAN show up twice in
the router's device list with two different IPs?

Furthermore, the device in question was accessing the 3Mb/s Internet
connection at 220K until I cleared (reset) the device list, whereupon
the device was then able to connect at 2.7 Mb/s (all speed tests were
run on dslreports.com).

Can anyone explain to me how a single device managed to have two IPs
assigned to it by the built-in DHCP server? BTW, the device was listed
exactly the same except for the IP numbers. Does this kind of thing ever
happen to WAN DHCP servers?

TIA for any enlightenment.

(E-Mail Removed)lid wrote:
> Here's a question:
>
> How can a single wireless device (a laptop) on a LAN show up twice in
> the router's device list with two different IPs?
>
> Furthermore, the device in question was accessing the 3Mb/s Internet
> connection at 220K until I cleared (reset) the device list, whereupon
> the device was then able to connect at 2.7 Mb/s (all speed tests were
> run on dslreports.com).
>
> Can anyone explain to me how a single device managed to have two IPs
> assigned to it by the built-in DHCP server? BTW, the device was listed
> exactly the same except for the IP numbers. Does this kind of thing ever
> happen to WAN DHCP servers?
>
> TIA for any enlightenment.

Basically YMMV

What IP address you get from a DHCP server depends on the server
software. Some of them have "memory" and will reissue an IP address to
a request from the same MAC address. Some of them don't and just give
out the next IP address.

One other factor: Most inexpensive wireless WAPs have their DHCP memory
in RAM and the box could have been restarted.

Did you ever connect the laptop hardwired through the
Ethernet port? If so, the router sees that as a different
MAC address and will assign separate IPs.
Mine does that.

John Richards

<(E-Mail Removed)> wrote in message news:bearclaw-(E-Mail Removed)...
> Here's a question:
>
> How can a single wireless device (a laptop) on a LAN show up twice in
> the router's device list with two different IPs?
>
> Furthermore, the device in question was accessing the 3Mb/s Internet
> connection at 220K until I cleared (reset) the device list, whereupon
> the device was then able to connect at 2.7 Mb/s (all speed tests were
> run on dslreports.com).
>
> Can anyone explain to me how a single device managed to have two IPs
> assigned to it by the built-in DHCP server? BTW, the device was listed
> exactly the same except for the IP numbers. Does this kind of thing ever
> happen to WAN DHCP servers?
>
> TIA for any enlightenment.

In article <(E-Mail Removed)>,
Roy <(E-Mail Removed)> wrote:
>(E-Mail Removed) wrote:
>> Here's a question:
>>
>> How can a single wireless device (a laptop) on a LAN show up twice in
>> the router's device list with two different IPs?
>>
>> Furthermore, the device in question was accessing the 3Mb/s Internet
>> connection at 220K until I cleared (reset) the device list, whereupon
>> the device was then able to connect at 2.7 Mb/s (all speed tests were
>> run on dslreports.com).
>>
>> Can anyone explain to me how a single device managed to have two IPs
>> assigned to it by the built-in DHCP server? BTW, the device was listed
>> exactly the same except for the IP numbers. Does this kind of thing ever
>> happen to WAN DHCP servers?
>>
>> TIA for any enlightenment.
>
>Basically YMMV
>
>What IP address you get from a DHCP server depends on the server
>software. Some of them have "memory" and will reissue an IP address to
> a request from the same MAC address. Some of them don't and just give
>out the next IP address.
>
>One other factor: Most inexpensive wireless WAPs have their DHCP memory
>in RAM and the box could have been restarted.

I would not expect the WAP to issue an IP address, unless the device
requested one. If the device held a valid lease for that subnet, It should
have used it, unless the device had been disconnected, in which case it
should have requested it's previous address if the lease was still valid.

If the WAP had been restarted, I would expect the ARP table to be flushed
as well.


--
-- Welcome My Son, Welcome To The Machine --
Bob Vaughan | techie @ tantivy.net |
| P.O. Box 19792, Stanford, Ca 94309 |
-- I am Me, I am only Me, And no one else is Me, What could be simpler? --

In article <ReO9i.11342$(E-Mail Removed)> ,
"John Richards" <(E-Mail Removed)> wrote:

> Did you ever connect the laptop hardwired through the Ethernet port?

No, the computer's owner is not technically adept. Wireless access
looks akin to magic to her. I doubt she has any idea what the computer's
ethernet port is for-- or any other hole on her box except maybe for the
CD slot. She'd be like, "5 cats? What are their names?" Seriously.

So far, the possibility of a short power outage sounds most likely.

I still wonder how the device list duplication could so adversely affect
her throughput, though. It seems obvious that was the problem, since it
cleared up when I reset the list.

In article <f48h7t$nc5$(E-Mail Removed)>,
(E-Mail Removed) (Bob Vaughan) wrote:

> I would not expect the WAP to issue an IP address, unless the device
> requested one. If the device held a valid lease for that subnet, It should
> have used it, unless the device had been disconnected, in which case it
> should have requested it's previous address if the lease was still valid.
>
> If the WAP had been restarted, I would expect the ARP table to be flushed
> as well.

As fuzzy as my understanding becomes starting at this level of
discussion, this is essentially what I would expect from router behavior.

I guess without knowing exactly what went on beforehand, it would be
pretty much impossible to diagnose the exact cause of the glitch. Still,
if nothing else, now I have something new to look for when
troubleshooting an apparently slow broadband connection.

Can anyone think of a good reason NOT to reset the device list?