Let's say you have 2 call managers. (Publish/subscriber) Typically, customers purchase this for redundancy correct? Well, I have a question related to TFTP/DHCP redundancy. In any given scope, I can (I think) only assign <1> tftp server. (option 150) Correct? Typically, I would set up the publisher to be the TFTP server and all other devices register to the subscriber. (the glass house theory) Now what happens in a power outage scenario where the publisher does not come back up? The phones will never find their TFTP server therefore never registering. Ideally, I'd like to give multiple tftp servers for redundancy purposes.
Now i know the phones have an "alternate tftp" option that you can <manually> set. But for 1000+ phones that would be virtually impossible to manage. Any solution or suggestions to this problem? I'm hoping for an EASY fix....
You are correct in your assessment about only being able to tell a phone/gateway about a single TFTP server to use. The server used is either told through DHCP or through static configuration (like Alternate TFTP entry).
But I don't think the problem you describe with a power outage is quite as severe as you are think. If the TFTP server is down, then phones/gateways will continue to operate normally. If the device resets for whatever reason and the TFTP server is still not reachable, then the device will continue to use the information it had previously received from the TFTP server, which instructs it which CallManagers to register and in what order.
While the TFTP server is not available, you would not be able to bring new phones online, but also in the scenario you described, if the publisher database is offline then you can't change anything anyway. But you certainly don't have to use TFTP on the publisher if you don't wish to. You could have one server each for functions like TFTP, glass house database, web components, and then have one or more servers for Cisco CallManager.
Dave on our campus DHCP servers, we use QIP, we were able to setup option 150 as a list of ip addresses and put in publisher as the first server and the subscriber as the second. This option might not be available in other DHCP servers. It has been a long time since we verified this but if I'm not mistaken the phones only show the first tftp server in the option 150 list but infact it does know about the second one. Can you verify this? This was one of our biggest issues on points of failure as well and if we haven't truly fixed it by making option 150 a list, we should go back to the drawing board.
Thank you for your input.....have you tested this completely? I had this (power outage) happen in a production network and the devices NEVER reregistered. I am going to test this in our lab a little more but I haven't seen this to be true. (the devices will retain their last good config)
Actually I went back and tested this again and Dave is right. Even though we had a list of tftp servers configured, the phones only use the first server in the list. If that server is unavailable, the phones (tested with 7960) default to the last known list of callmanagers within less than a minute after the phone reboots.
I guess the next question is, How long they retain this config after a power outage?
Until the DHCP lease runs out. The phone keeps track of the expiration time and will try to renew at the standard intervals. If no renewal is possible during this time and the lease expires according to what the phone remembers, then it should not communicate using that IP address and try to get DHCP anew.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.