[cisco-voip] DHCP Migration Strategy - RFC

Fri Sep 25 00:09:42 EDT 2009

I tested out migrating to a new DHCP server tonite and it worked out well. I have to go through the logs in more detail to see if our server saw any conflicts, or if that even went into the logs, but we didn't have any IP addr conflicts as far as I can tell. 

That being said, I had a colleague who was on the phone, and although the lease time had expired for that phone (it even dissappeared from the lease list on the server) it did not reboot until he hung up the phone. 

So that was kinda nice. 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 

----- Original Message ----- 
From: "Wes Sisk" <wsisk at cisco.com> 
To: "Scott Voll" <svoll.voip at gmail.com> 
Cc: "Lelio Fulgenzi" <lelio at uoguelph.ca>, "cisco-voip voyp list" <cisco-voip at puck.nether.net> 
Sent: Friday, September 18, 2009 10:13:37 AM GMT -05:00 US/Canada Eastern 
Subject: Re: [cisco-voip] DHCP Migration Strategy - RFC 

that is correct, phones reboot if IP changes. 

most dhcp servers will not NAK a renew request. This was implemented to facilitate redudant DHCP servers for an address scope. Since DHCP servers will not NAK your client leases have to expire before they will get a new address. 

/wes 

On Thursday, September 17, 2009 5:44:11 PM, Scott Voll <svoll.voip at gmail.com> wrote: 

It's been a really long time ago, but has anyone had issue with short lease times. Doesn't the phone blip every time it gets a new IP? IF memory serves me correct I had calls cutting out when the phones grabbed a new IP. Was that just a Firmware load I had at the time? 

Scott 

On Thu, Sep 17, 2009 at 2:39 PM, Lelio Fulgenzi < lelio at uoguelph.ca > wrote: 

sweet! thanks. 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 

----- Original Message ----- 
From: "Matthew Loraditch" < MLoraditch at heliontechnologies.com > 
To: "Lelio Fulgenzi" < lelio at uoguelph.ca > 

Cc: "cisco-voip voyp list" < cisco-voip at puck.nether.net >, "Jason Fuermann" < JBF005 at shsu.edu > 
Sent: Thursday, September 17, 2009 5:36:34 PM GMT -05:00 US/Canada Eastern 
Subject: RE: [cisco-voip] DHCP Migration Strategy - RFC 

Go Google: http://www.infoblox.com/import/ 

I just look at the parts of the wizard I could get to w/o an infoblox and it says you can, albeit looks like you have to do the whole server from the included instructions not sure if that would mess you up or not 

Matthew Loraditch 
1965 Greenspring Drive 

Timonium, MD 21093 
support at heliontechnologies.com 
(p) (410) 252-8830 
(F) (443) 541-1593 

Visit us at www.heliontechnologies.com 
Support Issue? Email support at heliontechnologies.com for fast assistance! 

From: Lelio Fulgenzi [mailto: lelio at uoguelph.ca ] 
Sent: Thursday, September 17, 2009 5:32 PM 
To: Matthew Loraditch 
Cc: cisco-voip voyp list; Jason Fuermann 
Subject: Re: [cisco-voip] DHCP Migration Strategy - RFC 

Central DHCP server is InfoBlox. I'll have to see if they can import a Windows DHCP export file. 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 

----- Original Message ----- 
From: "Matthew Loraditch" < MLoraditch at heliontechnologies.com > 
To: "Lelio Fulgenzi" < lelio at uoguelph.ca >, "Jason Fuermann" < JBF005 at shsu.edu > 
Cc: "cisco-voip voyp list" < cisco-voip at puck.nether.net > 
Sent: Thursday, September 17, 2009 5:27:51 PM GMT -05:00 US/Canada Eastern 
Subject: RE: [cisco-voip] DHCP Migration Strategy - RFC 

Is your central DHCP server windows as well? If so you can migrate the Scope, I’ve done it many times, shut down current dhcp server, export to file, copy file to new server, import and activate it and update ip helper, can be done in 5 to 10 minutes. all current leases and all other settings related to the scope come over. You can do it scope by scope or the whole server at the same time. 

Matthew Loraditch 
1965 Greenspring Drive 

Timonium, MD 21093 
support at heliontechnologies.com 
(p) (410) 252-8830 
(F) (443) 541-1593 

Visit us at www.heliontechnologies.com 
Support Issue? Email support at heliontechnologies.com for fast assistance! 

From: cisco-voip-bounces at puck.nether.net [mailto: cisco-voip-bounces at puck.nether.net ] On Behalf Of Lelio Fulgenzi 
Sent: Thursday, September 17, 2009 5:23 PM 
To: Jason Fuermann 
Cc: cisco-voip voyp list 
Subject: Re: [cisco-voip] DHCP Migration Strategy - RFC 

Good catch - I'll see if the new server can do a ping or something first, and what ACLs we have to open to allow that. 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 

----- Original Message ----- 
From: "Jason Fuermann" < JBF005 at shsu.edu > 
To: "Wes Sisk" < wsisk at cisco.com >, "Lelio Fulgenzi" < lelio at uoguelph.ca > 
Cc: "cisco-voip voyp list" < cisco-voip at puck.nether.net > 
Sent: Thursday, September 17, 2009 5:18:35 PM GMT -05:00 US/Canada Eastern 
Subject: RE: [cisco-voip] DHCP Migration Strategy - RFC 

If I remember correctly we’ve had leases set to 30 minutes before without any issues. I wouldn’t go below that because the phone is going to be renewing at a 15 minute interval. I’d check on what DHCP server you’re using, some will check if an address is in use before issuing one (at least I’ve experienced that on windows DHCP), and on that same note, make sure there is enough overlap in the scopes so you don’t run out of leases due to addresses being blocked for conflicts. 

From: cisco-voip-bounces at puck.nether.net [mailto: cisco-voip-bounces at puck.nether.net ] On Behalf Of Wes Sisk 
Sent: Thursday, September 17, 2009 4:03 PM 
To: Lelio Fulgenzi 
Cc: cisco-voip voyp list 
Subject: Re: [cisco-voip] DHCP Migration Strategy - RFC 

depending on your nw topology this could still be a problem: 
CSCso60222 After DHCP Monitor service is stopped, IP is given to DHCP clients 

make sure DHCP DISCOVER (and renew as a subset of DISC) will not reach the CM server. 

Phones tend to go haywire when lease duration goes below something like 5 minutes so I would stay very clear of that on the order of 1 hour. I don't have the bug for that handy. 

/Wes 

On Thursday, September 17, 2009 4:51:28 PM, Lelio Fulgenzi <lelio at uoguelph.ca> wrote: 

So, I'm planning on moving the DHCP service off a CallManager subscriber to our central DHCP service. Past experience tells me that this shouldn't be too much of an issue, but there are some things to look out for. For example, IP address conflicts on phones causes both phones to reset. 

Here's what I'm planning on doing (testing out on one scope to begin with): 

    1. Lower lease time on CallManager subscriber DHCP server from 8 days to 1 hour. Wait until all phones have a 1 hour lease. 
    2. Change IP helper address on interface to new DHCP server. 
    3. Deactivate scope on CallManager subscriber DHCP server. 
    4. Wait one hour until all phones have new lease on new DHCP server and all IP address conflicts are resolved. 
    5. Remotely reset phones that are not co-operating. 

Two questions: 

    • Is having a 1 hour lease time on the subscriber an issue? It's a 7835 from about 4 years ago and it does nothing else other than DHCP/TFTP. 
    • Can I go a step further and lower the lease time to 30min or even 15 min without significant concern? 

We have about 7500 phones. 
--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 
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