[cisco-voip] DHCP Migration Strategy - RFC

[Wes Sisk]

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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