[cisco-voip] DHCP Migration Strategy - RFC

[Lelio Fulgenzi]

Thanks. We're running v4.1(3)sr something. The bug says first found in v6. Since that's the appliance model, and we're running Windows, I'm hoping Windows DHCP tool is robust enough that if I deactivate a scope it won't give it an IP address. 

What's your thoughts on 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: "Wes Sisk" <wsisk at cisco.com> 
To: "Lelio Fulgenzi" <lelio at uoguelph.ca> 
Cc: "cisco-voip voyp list" <cisco-voip at puck.nether.net> 
Sent: Thursday, September 17, 2009 5:02:30 PM GMT -05:00 US/Canada Eastern 
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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