[cisco-voip] DHCP Behavior

[Voll, Scott]

Am I the only one that has had problems with DHCP leases and kicking
phones offline during the DHCP change?

 

I had a 3 day lease and each day I would get complains of phone briefly
not working.  Figured out it was the lease expiring and changed it to a
longer lease (infinite) ;-)

 

Scott

 

________________________________

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Lelio Fulgenzi
Sent: Thursday, June 07, 2007 6:46 AM
To: Matt Slaga (US); Ed Leatherman; ciscovoip
Subject: Re: [cisco-voip] DHCP Behavior

 

But the phone has the IP address of the DHCP server - so it will try to
communicate directly. Unless the scope or server is stopped.

 

Ok, maybe two minutes is a bit harsh, 5 minutes should be ok. we did
this on a network of about 7500 and it was not a problem over the 5 days
in order to let them old leases expire.

 

As they get to the new lease from the new DHCP server they get the
longer lease.

 

 

------------------------------------------------------------------------
--------
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo."
WJR

	----- Original Message ----- 

	From: Matt Slaga (US) <mailto:Matt.Slaga at us.didata.com>  

	To: Lelio Fulgenzi <mailto:lelio at uoguelph.ca>  ; Ed Leatherman
<mailto:ealeatherman at gmail.com>  ; ciscovoip
<mailto:cisco-voip at puck.nether.net>  

	Sent: Thursday, June 07, 2007 9:39 AM

	Subject: RE: [cisco-voip] DHCP Behavior

	 

	If you are not changing IP networks, then you can leave them the
way they are and let them change DHCP servers on their own.  If you set
it to 1 minute, every phone will be requesting a new address every 30
seconds which would have a negative impact on users.

	 

	Let them migrate on their own over a few days.  The phones don't
care what the dhcp server is, as long as one responds.

	 

	From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Lelio Fulgenzi
	Sent: Thursday, June 07, 2007 9:35 AM
	To: Ed Leatherman; ciscovoip
	Subject: Re: [cisco-voip] DHCP Behavior

	 

	I would set the lease time to about 2 minutes for a migration
like this.

	 

	Typically, lease renewals happen 1/2 way through the lease time.

	 

	The new DHCP server should ping the address before it assigns
it, but you might get IP address conflicts. In that case, the phone
reboots and tries to get a new address.

	 

	
------------------------------------------------------------------------
--------
	Lelio Fulgenzi, B.A.
	Senior Analyst (CCS) * University of Guelph * Guelph, Ontario
N1G 2W1
	(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
	
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
	"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo
buffalo."      WJR

		----- Original Message ----- 

		From: Ed Leatherman <mailto:ealeatherman at gmail.com>  

		To: ciscovoip <mailto:cisco-voip at puck.nether.net>  

		Sent: Thursday, June 07, 2007 9:31 AM

		Subject: [cisco-voip] DHCP Behavior

		 

		I'm getting ready to start migrating ip phones off of
the DHCP service on our callmanager to a DHCP appliance (infoblox). I've
got the lease timer down to 1 hour now on my first set of phones, my
next step is going to be to change the ip helper-address on the routers
and deactivate the scope in DHCP on the windows box. 
		
		How do the phones behave when they try to renew and
their original DHCP server isnt there? Do i need to reset all of them,
or will they find the new server on their own? 
		
		-- 
		Ed Leatherman
		Senior Voice Engineer
		West Virginia University
		Telecommunications and Network Operations 

		
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