{DANGEROUS?} SV: Option 82 fast change
Marc Perea
marccp at srttel.com
Fri Sep 12 13:25:45 UTC 2008
Hi again. Yes, we can depend on the remote equipment to set the option82.circuit-ID ALWAYS the same. Our implementation includes a DSLAM double Vlan tagging and inserting L2 option 82 info. Our circuit-ID in the DHCP packet is not allowed for the client to set, it happens at the DSLAM.
Thank you for the recommendation of ending the leasetime early with omapi, I tried removing a lease but not adjusting the timing - I'll give that a shot.
Be careful what you wish for.
Over-riding leases is likely to be a source of problems.
Can you depend on the customer to set the Client ID of the
equipment to a site-specific string chosen by you? This may
be an immediate work-around, as the ISC DHCP server (IIUC)
heeds a Client-ID string in preference to a MAC Address.
IIRC, there has been some discussion on this list about the
desirability of a configuration option to force the MAC address
(rather than the Client ID string) to be the key for the lease.
If this idea reaches the top of the work-list, it might be
useful to consider providing an additional flavour of this
option which would allow the lease key to be derived from
Option-82 data.
Best regards,
Niall O'Reilly
University College Dublin IT Services
------------------------------
Date: Thu, 11 Sep 2008 19:01:48 +0200
From: Christof Chen <christof at chen.de>
Subject: Re: {DANGEROUS?} SV: Option 82 fast change
Anders Rosendal schrieb:
>
> Have a public network where customers are assigned one "static ip" through dhcp, and when they change equipment on there ports they don't get the IP for the "new" equipment.
> Would like to see some kind of leasetime-override.
>
You can override the lease-end time with omapi.
This isn't as nice as using the switchport id as an client-identifier,
but way easier than stopping dhcpd, editing the lease file and
restarting the daemon.
Christof Chen
Marc Perea
Network Support Engineer
SRT Communications, Inc.
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