DHCP options for clustered systems

[mynnattor]

I have two systems that are clustered that i took over, i am trying to figure out the dhcp for the smaller system. How do you specify two servers for failover in third party windows dhcp server?

dhcp is enabled in the larger system but disabled in the smaller one. looking at the settings below can someone please explain to me what i need, what is missing and how this works?


dhcpd option 3 ip 10.255.249.1
dhcpd option 43 ascii id:ipphone.mitel.com;sw_tftp=172.16.27.18;call_srv=172.16.27.18;l2p=6;dscp=46
dhcpd option 125 ascii id:ipphone.mitel.com;sw_tftp=172.16.27.18;call_srv=172.16.27.18;l2p=6;dscp=46
dhcpd option 128 ip 172.16.27.18
dhcpd option 129 ip 172.16.27.18
dhcpd option 130 ascii MITEL_IP_PHONE
dhcpd option 132 hex 0000.0016
dhcpd option 133 hex 0000.0006

[iboyd]

With the Windows Server, you should be able to configure either Option 43 or 125 with the a hex value.  I have a tool from Mitel called DHCP OPT, which spits out the correct Hex string to put in for 125.  For fail over, I would adjust the lease timers to that way the phones will prefer the primary, but then once it doesn't get an address from it, it will take the shorter lease timer from the Windows server.  I have not seen any fail over options on the Mitel systems so far...

[tekmyster]

iboyd, option 125 has one tftp server and one call server listed, how would we list two (the primary and clustered)  would a comma separating the IPs suffice? is there another field that needs to be put in to the string to allow the phone to realize it is part of a cluster?

[iboyd]

If Ralph can show me how to upload a file to this forum, you can use the DHCP option generator that I have, this lets you generate everything correctly, but yes it looks like a comma between the 2 call servers will suffice, how ever this program only lets you define 1 TFTP server, so I am not sure how to address that bit.

-Ian

[acejavelin]

Honestly, on many installations you do not need to specify the second ICP in DHCP, although it could be a good idea depending on network setup...

When the phones register to the primary ICP they will be told what their secondary ICP is by the primary controller. The DHCP option of a secondary ICP is only for initial registration.

[ralph]

If Ralph can show me how to upload a file to this forum, you can use the DHCP option generator that I have, this lets you generate everything correctly, but yes it looks like a comma between the 2 call servers will suffice, how ever this program only lets you define 1 TFTP server, so I am not sure how to address that bit.

-Ian

Thanks, Ian.
I need to be careful about what is posted on the forum.  As far as I know that is software that Mitel created and therefore I don't have the rights to publish it.
But I'm thinking that Ace is correct.  If you're in a clustered environment then you probably don't have to worry about it.

Ralph

[acejavelin]

In fact, in a clustered environment, every phone can register to any ICP in the cluster regardless of whether the phone resides there as primary, secondary, or not at all. All cluster elements know where all phones reside (except Local Only DNs) so any controller they contact will tell them which ICP is their primary and secondary. We have a 13 site cluster setup this way, and all phones register to Node 1 via DHCP, from there it tells them their resilient pair to use. 

The only time this becomes a problems is if Node 1 is done more than a day or so... DHCP leases of phones start expiring and they can't renew if the node is down, this has only happened once in 10 years and that was because of a storm on a Friday night took out the system and no one really discovered it until 7am Monday.

[VinceWhirlwind]

So your mitigation for an extended outage on your primary ICP would be to edit all your DHCP scopes and change the IP address to that of the secondary.