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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

Plusnet router - carry-over of configured settings from previous PN router



 
 
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  #1  
Old March 5th 19, 01:00 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 466
Default Plusnet router - carry-over of configured settings from previous PN router

Plusnet have sent me a new PN-branded Hub One to replace the PN Technicolour
TG582 router, to see if it achieves a higher DSL speed (actually there's no
discernable difference in atten/margin/power/sync speed, but it was worth a
try).

On the old router I'd set up various reserved IP addresses for
computers/printer that I needed to refer to by a static address.

I'm intrigued that the new router has allocated those same addresses, and
they are even described as "static"/Always use this IP address rather than
"DHCP" in the Hub One's Advanced | Devices | (click on device name) menu. I
was about to configure those settings and see that I don't need to.

I've checked and the computers are definitely configured to request an
address (always the same one) by DHCP, and are not set to static addresses.


So it looks as if the old router has communicated to PlusNet the
customisations that I've made and they have then echoed them to the new
router. Is that possible?

I know they pre-configure the DSL logon name and password into their
routers, but I didn't know they could also configure reserved IP addresses.

  #2  
Old March 5th 19, 01:17 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 466
Default Plusnet router - carry-over of configured settings from previous PN router

"NY" wrote in message
...
Plusnet have sent me a new PN-branded Hub One to replace the PN
Technicolour TG582 router, to see if it achieves a higher DSL speed
(actually there's no discernable difference in atten/margin/power/sync
speed, but it was worth a try).

On the old router I'd set up various reserved IP addresses for
computers/printer that I needed to refer to by a static address.

I'm intrigued that the new router has allocated those same addresses, and
they are even described as "static"/Always use this IP address rather than
"DHCP" in the Hub One's Advanced | Devices | (click on device name) menu.
I was about to configure those settings and see that I don't need to.

I've checked and the computers are definitely configured to request an
address (always the same one) by DHCP, and are not set to static
addresses.


So it looks as if the old router has communicated to PlusNet the
customisations that I've made and they have then echoed them to the new
router. Is that possible?

I know they pre-configure the DSL logon name and password into their
routers, but I didn't know they could also configure reserved IP
addresses.



Or does the DHCP protocol have a way of communicating the information:

Computer wanting IP address from new router: "Last time I was given this
address and it was set as a reserved address"

New Router which has never seen this device befo "OK, I'll set myself to
do the same - using this same reserved address"

(using the MAC address as the unique computer ID).

  #3  
Old March 5th 19, 03:20 PM posted to uk.telecom.broadband
Invalid
external usenet poster
 
Posts: 141
Default Plusnet router - carry-over of configured settings from previous PN router

In message , NY
writes
"NY" wrote in message
...
Plusnet have sent me a new PN-branded Hub One to replace the PN
Technicolour TG582 router, to see if it achieves a higher DSL speed
(actually there's no discernable difference in atten/margin/power/sync
speed, but it was worth a try).

On the old router I'd set up various reserved IP addresses for
computers/printer that I needed to refer to by a static address.

I'm intrigued that the new router has allocated those same addresses,
and they are even described as "static"/Always use this IP address
rather than "DHCP" in the Hub One's Advanced | Devices | (click on
device name) menu. I was about to configure those settings and see
that I don't need to.

I've checked and the computers are definitely configured to request
an address (always the same one) by DHCP, and are not set to static
addresses.


So it looks as if the old router has communicated to PlusNet the
customisations that I've made and they have then echoed them to the
new router. Is that possible?

I know they pre-configure the DSL logon name and password into their
routers, but I didn't know they could also configure reserved IP
addresses.



Or does the DHCP protocol have a way of communicating the information:

Computer wanting IP address from new router: "Last time I was given
this address and it was set as a reserved address"

New Router which has never seen this device befo "OK, I'll set
myself to do the same - using this same reserved address"

(using the MAC address as the unique computer ID).


As I understand DHCP the latter is the case.

A device that already has an address will attempt to renew the lease on
the address at the 50% point in the lease time.

It does so by requesting a renewal from the DHCP server, and the message
contains the existing IP address for which it is requesting renewal.

I suspect you changed the router without switching off the clients, and
that the new router used the same IP address as the old one.
Consequently all the devices will have ( at some point ) requested
renewal of their existing IP addresses.

The new router must assume that devices that already have an IP address
(which it has not assigned) must have "static" addresses (ones assigned
by some other mechanism) and sets up it's tables accordingly.

If you had switched off all the devices before changing the route,
started up the router first and then the devices one by one, I suspect
you would have got a different result.
--
Invalid
  #4  
Old March 5th 19, 06:02 PM posted to uk.telecom.broadband
Graham J[_3_]
external usenet poster
 
Posts: 29
Default Plusnet router - carry-over of configured settings from previousPN router

Invalid wrote:

[snip]


As I understand DHCP the latter is the case.

A device that already has an address will attempt to renew the lease on
the address at the 50% point in the lease time.

It does so by requesting a renewal from the DHCP server, and the message
contains the existing IP address for which it is requesting renewal.

I suspect you changed the router without switching off the clients, and
that the new router used the same IP address as the old one.
Consequently all the devices will have ( at some point ) requested
renewal of their existing IP addresses.

The new router must assume that devices that already have an IP address
(which it has not assigned) must have "static" addresses (ones assigned
by some other mechanism) and sets up it's tables accordingly.

If you had switched off all the devices before changing the route,
started up the router first and then the devices one by one, I suspect
you would have got a different result.


Many new routers have "sticky" settings, so that the IP issued to a
given MAC address by the DHCP service is always "remembered" for
subsequent requests by that client.

So the description given by the new router, i.e. "static"/Always use
this IP address rather than "DHCP" isn't really meaningful. What I
think it means is: "The DHCP server remembers the MAC addresses it has
seen and which IP addresses it issued to those MAC address last time,
and will issue the same addresses next time."

I'm not sure how it handles the situation where it runs out of
previously unused IP addresses - perhaps if an IP address is currently
not in use it can be re-allocated presumably on the basis of time since
it was last used. Could be embarrassing where the clients are always
changing - such as in a hotel or coffee-shop.

Other routers have "binding" which can be enabled optionally, where the
DHCP server knows that specific MAC addresses must be issued with
specific IP addresses. They can also have "reservations", meaning that
certain IP addresses will never be issued.


--
Graham J
  #5  
Old March 5th 19, 06:42 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 466
Default Plusnet router - carry-over of configured settings from previous PN router

"Graham J" wrote in message
...
I suspect you changed the router without switching off the clients, and
that the new router used the same IP address as the old one. Consequently
all the devices will have ( at some point ) requested renewal of their
existing IP addresses.

The new router must assume that devices that already have an IP address
(which it has not assigned) must have "static" addresses (ones assigned
by some other mechanism) and sets up it's tables accordingly.

If you had switched off all the devices before changing the route,
started up the router first and then the devices one by one, I suspect
you would have got a different result.


Many new routers have "sticky" settings, so that the IP issued to a given
MAC address by the DHCP service is always "remembered" for subsequent
requests by that client.

So the description given by the new router, i.e. "static"/Always use this
IP address rather than "DHCP" isn't really meaningful. What I think it
means is: "The DHCP server remembers the MAC addresses it has seen and
which IP addresses it issued to those MAC address last time, and will
issue the same addresses next time."


The router has a config page for each PC that has been assigned an address
by DHCP. Those PCs which had previously been allocated a reserved address
were described on that page as "Always use this IP address = yes" and "IP
address assignment=static", whereas other devices that I had not reserved an
address for are "Always... = no" and "IP address assignment=DHCP".

So the router, when first booted up, somehow "knew" which devices had
previously been given a reserved address.

I hadn't rebooted the PCs, so it was renewal of existing IP rather than
allocation from "cold", but even allowing for that, does DHCP allow devices
to tell the router not only their existing IP but also that this address
should be reserved permanently, rather than allocated at random from the
pool?

  #6  
Old March 5th 19, 07:03 PM posted to uk.telecom.broadband
Graham.[_3_]
external usenet poster
 
Posts: 299
Default Plusnet router - carry-over of configured settings from previous PN router

Plusnet have sent me a new PN-branded Hub One to replace the PN Technicolour
TG582 router, to see if it achieves a higher DSL speed (actually there's no
discernable difference in atten/margin/power/sync speed, but it was worth a
try).

On the old router I'd set up various reserved IP addresses for
computers/printer that I needed to refer to by a static address.

I'm intrigued that the new router has allocated those same addresses, and
they are even described as "static"/Always use this IP address rather than
"DHCP" in the Hub One's Advanced | Devices | (click on device name) menu. I
was about to configure those settings and see that I don't need to.

I've checked and the computers are definitely configured to request an
address (always the same one) by DHCP, and are not set to static addresses.


So it looks as if the old router has communicated to PlusNet the
customisations that I've made and they have then echoed them to the new
router. Is that possible?

I know they pre-configure the DSL logon name and password into their
routers, but I didn't know they could also configure reserved IP addresses.



I am not using reserved adresses, but I do have several static ones
outside of the DHCP scope.

It's probably down to the remote management platform they use.
Log on to the router advanced settings, then troubleshooting and then
Event Log click next to get to the earliest log entries and look for
references to TR069 and CWPM

When the router first fired up you may well see
System up, firmware version: 4.7.5.1.83.8.259

followed by an upgrade to

System up, firmware version: 4.7.5.1.83.8.263

I imagine it's a two way street and the router uploads its
configuration to base.

The Hub One (BT HH5) is not well regarded. A slightly misconfigured
VoIP client in my Android phone was capable of repeatedly crashing the
router invoking its Watchdog function!

Boot reason: watchdog reset (cause: 0x0)

More seriously are the almost nightly re syncs, that are ominously
proceeded by 3 seconds with:

PPP LCP Send Termination Request [User request]

There's lots on the Web about this event, but nothing useful I can do
about it AFAICS apart from buy a better router.

Oh, I nearly forgot, just in case you didn't know, the Hub One/HH5
(and quite likley the Technicolour) will not work on 10.0.0.0 LAN
subnet, which has always been my range of choice.



--
Graham.

%Profound_observation%
  #7  
Old March 5th 19, 09:06 PM posted to uk.telecom.broadband
Graham J[_3_]
external usenet poster
 
Posts: 29
Default Plusnet router - carry-over of configured settings from previousPN router

NY wrote:

[snip]


The router has a config page for each PC that has been assigned an address
by DHCP. Those PCs which had previously been allocated a reserved address
were described on that page as "Always use this IP address = yes" and "IP
address assignment=static", whereas other devices that I had not
reserved an
address for are "Always... = no" and "IP address assignment=DHCP".


I think that's meaningless.

A static assignment is one configured in the client device itself.
Because of this, the client never makes a DHCP request, so no entry will
be made in any DHCP table.

However, all devices on the LAN, including the router, may in due course
build an ARP table linking the MAC address with the IP of such a
statically configured device. Devices will do this if they have a need
to communicate with the statically configured thing.

The router will probably enter this MAC address in its ARP table, but
only because - when issuing an IP address to something else - it will
check whether the IP address it proposes to issue is already in use.
Some routers may scan the whole subnet to build a list of addresses that
are in use. So when the router finds an IP address that is already in
use it may "remember" it and note that it did not itself issue that
address, so describe it as "static".


So the router, when first booted up, somehow "knew" which devices had
previously been given a reserved address.


No, I think it assumed any existing addresses were static, as described
above

I hadn't rebooted the PCs, so it was renewal of existing IP rather than
allocation from "cold", but even allowing for that, does DHCP allow devices
to tell the router not only their existing IP but also that this address
should be reserved permanently, rather than allocated at random from the
pool?


No, see:

https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol

which includes the line "A DHCP client may also request its last known
IP address".

Consider the circumstances under which a client might issue a DHCP request:

1. Power on.

2. If already powered up, connection of the network interface (either
wired or wireless) directly to the router.

3. When commanded by the user. (e.g. ipconfig /renew)

At power on, some printers will use the IP address they had previously
received by DHCP even if a different address has since been bound in the
router, and therefore may require some sort of hard reset. I've never
investigated the detail, simply learned to live with the issue.

In the OP's case, replacing the router might not have invoked option 2
if there was a network switch between the router and the client. The
client would never have seen its interface disconnect, and any ongoing
requests requiring the router would simply have failed. Once the new
router was running, that client's MAC and IP address would have been
discovered (possibly because the client requested something requiring
the router, or because the router scanned the subnet). Note that if the
new router had been configured with a different subnet then the client
would not have communicated properly until its IP address was refreshed
(by any of steps 1, 2 or 3).

Its always possible that the client or router software designer failed
to understand the DHCP specification or (as often with Microsoft) chose
to implement their system differently.



--
Graham J
  #8  
Old March 5th 19, 09:21 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 466
Default Plusnet router - carry-over of configured settings from previous PN router

"Graham J" wrote in message
...
NY wrote:

[snip]


The router has a config page for each PC that has been assigned an
address
by DHCP. Those PCs which had previously been allocated a reserved address
were described on that page as "Always use this IP address = yes" and "IP
address assignment=static", whereas other devices that I had not reserved
an
address for are "Always... = no" and "IP address assignment=DHCP".


I think that's meaningless.

A static assignment is one configured in the client device itself. Because
of this, the client never makes a DHCP request, so no entry will be made
in any DHCP table.


Yes I think their use of the word "static" is misleading. I too think of a
static IP as one set at the client which does not make a DHCP request. Same
result but by different means. The router should probably use the word
"reserved" rather than "static".

I tend to prefer the reserved DHCP approach to a true static address,
especially for a portable device like a phone or a laptop, because this
means that the device will get a fixed address when it's on my home network
(so things that refer to the laptop by IP can be hard-coded to do so) but
will get whatever address is available on any other network (a friend's or
one in a hotel).

A true static address is an accident waiting to happen if it is within the
scope of the router's DHCP.


I'm trying to remember now why I used reserved DHCP for the computers on the
LAN but static addresses for the printer and webcams (using addresses
outside the DHCP scope). I wonder why I didn't use the same mechanism for
all the devices that needed fixed addresses... One of life's mysteries.

  #9  
Old March 5th 19, 10:44 PM posted to uk.telecom.broadband
Graham J[_3_]
external usenet poster
 
Posts: 29
Default Plusnet router - carry-over of configured settings from previousPN router

NY wrote:

[snip]



I'm trying to remember now why I used reserved DHCP for the computers on
the LAN but static addresses for the printer and webcams (using
addresses outside the DHCP scope). I wonder why I didn't use the same
mechanism for all the devices that needed fixed addresses... One of
life's mysteries.


It may depend on the capabilities of the DHCP server in the router.

The "scope" is usually the range within which IP addresses are issued
when there is no other rule applied.

However, those routers which allow binding of IP address to MAC address
can usually bind any address, either within or outside of the "scope".

I've not seen a domestic router that allows for "reservation". I've
only seen this within a server such as Microsoft SBS2011, where the DHCP
service can "reserve" IP addresses so that they are never issued by the
DHCP service. There are circumstances where for reliability one might
have two DHCP servers; in this case one DHCP server might reserve a
block of addresses knowing that they are allocated by the other; and
vice versa.

Some routers and servers such as Microsoft SBS2011 will take a
significant time to function after power up. For a router this may be 2
minutes, but for SBS2011 it may be several tens of minutes if its UPS
has to recharge to an acceptable level following an unscheduled power
failure. During this time some devices might power up normally and of
course will fail to get allocated an IP address. Things such as
printers and webcams may well autoconfigure (169.254.x.y) and will stay
like that possibly until rebooted, or possibly until a technician
explicitly reconfigures the device.

For these devices, a static IP is good. It may also be the only thing
that the printer supplier understands!

Bound addresses are useful where you (as the support person) need to
know the device's IP. Where you have a proper server you will have DNS
resolution also, in which case you (as the support person) only have to
remember the name of the device you want.


--
Graham J
  #10  
Old March 6th 19, 12:51 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 466
Default Plusnet router - carry-over of configured settings from previous PN router

"Graham J" wrote in message
...
NY wrote:

[snip]



I'm trying to remember now why I used reserved DHCP for the computers on
the LAN but static addresses for the printer and webcams (using addresses
outside the DHCP scope). I wonder why I didn't use the same mechanism for
all the devices that needed fixed addresses... One of life's mysteries.


It may depend on the capabilities of the DHCP server in the router.

The "scope" is usually the range within which IP addresses are issued when
there is no other rule applied.

However, those routers which allow binding of IP address to MAC address
can usually bind any address, either within or outside of the "scope".

I've not seen a domestic router that allows for "reservation". I've only
seen this within a server such as Microsoft SBS2011, where the DHCP
service can "reserve" IP addresses so that they are never issued by the
DHCP service. There are circumstances where for reliability one might
have two DHCP servers; in this case one DHCP server might reserve a block
of addresses knowing that they are allocated by the other; and vice versa.


I think they might be some confusion (my fault!) with the use of the word
"reservation". I'm sure one router (maybe my old TP Link) uses the term to
describe an IP address which is permanently bound to a MAC address, so the
same PC always gets the same address from DHCP. I was using the word in that
sense, but maybe wrongly :-(

Evidently "reservation" really means addresses within the range of the scope
which are excluded from being handed out by DHCP, presumably because those
computers are set locally to a static address. In that situation I tend to
use static addresses which are within the subnet but which are outside the
scope, to avoid clashes. Plusnet's routers seem to set the scope to
192.168.1.65-253, leaving 1-63 within the subnet but outside the scope, and
therefore suitable for static addresses.

 




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