Which TFTP server is used in Call Manager

[Richard Dumag]

We have 11 remote sites and 2 hub sites.  First hub site (located in northern Cal) have 2 CMs, publisher and subscriber, the second hub site (located in southen Cal) has 1 subscriber.

7 of the remote sites are located in southern Cal and all phones are registered to the subscriber in southen Cal subscriber.  The rest are located in northen Cal and all phones are registered to the northen Cal publisher.

I have noticed on the phones on the souther Cal remote sites have their TFTP Server 1 and 2 pointing to the publisher and subscriber in northern Cal.  On the dhcp settings, the order of the TFTP servers are publisher, subscriber, subscriber (southern Cal).

Does this mean that all phones in southen Cal will go to the publisher for updates instead of subscriber in southern Cal which is closest to them?

I am about to upgrade the firmware on all the phones and concerned that all phones will go to the publisher to get the upgrade, which can be an issue.

Can I change the order of the TFTP servers in dhcp to point all southern Cal phones to the subscriber in Cal for TFTP service?

[David Hailey]

So, the way the DHCP Option 150 works I believe is purely based on a top-down nature.  In other words, if you have Pub (priority 1), Sub 1 (priority 2), and Sub 2 (priority 3) then IP phones will always attempt to connect to the TFTP server listed as priority 1.  Unless that connection explicity fails for some reason, the phone will connect to (in your case) Pub 1.  Only if the connection fails will the phone attempt the priority 2 entry and so forth.  So, yes - in your case, your phones may all very well be hitting the Publisher and the Publisher only.

You should be able to safely change the DHCP Option 150 priority for a particular site.  This really depends on how you have DHCP set up.  If you had one DHCP scope for ALL phones then changing priorities would change them for ALL phones.  If DHCP is manged more granularly, then you have more control here.  Whatever you do, the phones won't pick up the new settings until they are reset (which would happen during the firmware upgrade).

Hailey

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[Richard Dumag]

Each site have its own dhcp so I can change the priority on option 150 for each site.  I will make the change to one site first then test.

Thanks for the reply Hailey!