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New Member

CCM Express AS SRST?

Rather than configuring SRST on our routers could we somehow setup CCM Express to act as a CallManger Fallback. I realize that this would require having routers that are supporeted by CCM Express, which we do. The reason I ask this is it seems that alot more functionality could be maintained during CM outages with CCM Express.

6 REPLIES
Silver

Re: CCM Express AS SRST?

CCM express can be loaded on a router which can act as a integrated device .for more info you can use following link

http://www.cisco.com/en/US/products/sw/voicesw/ps4625/products_data_sheet09186a00801c6350.html

Silver

Re: CCM Express AS SRST?

If you configure your router for CCME, then the IP phones at that local site has to be registered to the CCME all the time. It cannot be configured like, the IP phones will register with the CallManager normally, and when there's an WAN outage to register with CCME.

New Member

Re: CCM Express AS SRST?

No thats not true.

I've set it up in my lab and the ip phones will always prefer to register with Call Manager first. Even if I have CCM Express and CCM 3.3.3 running at the same time. If I down my call manager 3.3.3 server, CCM Express will kick in. When I boot it back up, CCM Express gives way to CCM 3.3.3.

So there appear to be no problems with the ip phones failing over.

However, there are most likely issues with the local gateways requiring some configuration changes. SRST reconfigures the router correctly and calls work automatically out the gateway in failover scenarios. However, whith CCM Express it doesn't appear to work the same way. I've had to remove commands to allow full callflow the way I want it.

But more testing is required.

Paul

Re: CCM Express AS SRST?

Just to put my 2 cents in, my sources tell me that getting CCME and CCM to work together in a failover scenario is something that is activley being worked on so that the phones register to CM and fail-over to CCME and back to CM without admin intervention. I have also seen it work both ways depending on your network topology. I have seen phones always wanting to home to the gateway regardless of CMs status and times where they actually fail back and forth.

New Member

Re: CCM Express AS SRST?

The trick is in the DHCP Server's TFTP option. Leave it pointing to the CallManager Server.

If one set's up the CallManager server first so that it's fully functional (all IP phones register to it). Then setup CMExpress. CMExpress using the 12.3(4)T train will allow ip phones to register to it, even though the TFTP option is still set to CallManager (assuming the CallManager is actually down).

Paul

New Member

Re: CCM Express AS SRST?

Interesting thread. It appears that several of you have figured out that this config does work. However there are a number of caveats - the biggest one being keeping CCME configs and CCM configs in sync for system level features (Call Forward All, Hunt groups, etc.). We have discussed this internally, but have not tested to see what other caveats might exist. Please use at your own risk. I would ofcourse love to hear any discoveries you might find. You can mail this info to sarat@cisco.com. Thanks

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