Awesome detective work Mike...inspector Everest!


On Mon, Apr 7, 2014 at 9:00 PM, <public-request@talk.mikrotik.com.au> wrote:

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>    1. Re: DHCP bug rOSv6.10 (at least) (Mike Everest)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 8 Apr 2014 09:02:44 +1000
> From: "Mike Everest" <mike@duxtel.com>
> To: "'MikroTik Australia Public List'" <public@talk.mikrotik.com.au>
> Subject: Re: [MT-AU Public] DHCP bug rOSv6.10 (at least)
> Message-ID: <087201cf52b5$7cb57a20$76206e60$@duxtel.com>
> Content-Type: text/plain;       charset="us-ascii"
>
> Hi Folks,
>
> Latest news regarding this issue, MT have confirmed that it is a routerOS
> bug, and is addressed in v6.12 - Quoting one of the Janises:
>
> > Yes, exactly that problem is fixed in that build i linked.
> > It was our mistake, we forget that Option 82 must be at the end of option
> list,
> > cause those switches remove all options after option 82.
> > Now it is back in place and there should be no problem and no need to
> change
> > switch configurations.
>
> Cheers,  Mike.
>
>
> > -----Original Message-----
> > From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of
> Mike
> > Everest
> > Sent: Wednesday, 2 April 2014 2:58 PM
> > To: public@talk.mikrotik.com.au
> > Subject: [MT-AU Public] DHCP bug rOSv6.10 (at least)
> >
> > Hi Folks,
> >
> >
> >
> > I have received report of this bug behaviour before, but never seen it
> happen
> > myself, or been able to get any diagnostic at all until this afternoon.
> Thought I
> > would post in case it is useful info!
> >
> >
> >
> > This has been reported to us previously as "when customer gets DHCP
> lease,
> no
> > access to anything is possible.  When customer enters static lease,
> everything is
> > good.  Reboot router, everything fine again for a while. Then stops
> working"
> >
> >
> >
> > Today, I discovered the reason.  After some number of leases has been
> issued
> > by DHCP server,  some number in the vicinity of about 200 leases, new
> leases
> > are issued with bad subnet mask, no gateway and no DNS.  End result, of
> > course, is no connectivity.
> >
> >
> >
> > This is apparently just related to number of leases, not actual dhcp
> server
> > - i.e. the problem happens after the same number of leases are formed
> even
> > when there are 3 DHCP servers on 4 different subnetworks, or just one
> DHCP
> > server for all clients.
> >
> >
> >
> > Today, I had a chance to work with a fellow who had done some much better
> > diagnostic work on a network experiencing essentially the same behaviour
> -
> he
> > discovered that DHCP becomes broken after some time (or some number of
> > leases) in that clients no longer receive netmask, gateway or DNS detail.
> > Thus the client picks up IP address only, and a default mask (assume
> based
> on
> > address 'class') and blank gateway and DNS.
> >
> >
> >
> > The routerOS version in place omn that network is 6.10 - we have upgraded
> to
> > 6.11 and see if it happens again.
> >
> >
> >
> > If so, we'll grab some pcaps of DHCP traffic and report to MT - in the
> > meantime, if anyone has experience with this issue too, please post it!
> ;)
> >
> >
> >
> > Cheers,  Mike.
> >
> >
> >
> >
> >
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> End of Public Digest, Vol 2, Issue 5
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