[Gllug] OT: old router as switch or buy dedicated switch

[Matthew King]

Chris Bell <chrisbell at 3966.ukfsn.org> writes:

> On Fri 16 Oct, Tethys wrote:
>> 
>> --------
>> 
>> Chris Bell writes:
>> 
>> >   You could have problems if it tries to allocate NAT addresses using DHCP
>> >and conflicts with the new one.
>> 
>> No, you won't. DHCP is explicitly designed to allow multiple
>> independent DHCP servers on each subnet that don't communicate
>> with each other.
>> 
>> Tet
>
>    A friend has just managed to identify a series of problems caused by just
> that. A second ADSL connection was discontinued, leaving a forgotten ADSL
> modem acting as a local switch and issuing conflicting DHCP addresses.

This was probably caused by one of both of:

- Broken DHCP implementation on either of the routers not resolving
  conflicts properly

- DHCP on the old router still giving out details assuming it is the
  router.

The latter almost certainly played a part. I have no idea how many el
cheapo routers have broken DHCP implementations but I'll bet it's far
from zero. I mean why use a very good free DHCP server when you can pay
some developers to write your own broken version?

Matthew

-- 
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invariable experience that the company of a mere child is infinitely
preferable to that of a mere adult.
                                           --  Fran Lebowitz
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