Load-Balancing with CallManager Express

[Asad Raza]

Hello all,

I am trying to quote CME to a potential client, but he has a few questions on which I require assistance:

1) Can two CME routers be load-balanced so that phones can use either router as their gateway, depending on, for instance, available outgoing analog lines, etc?

2) They have tele-workers who would like to be able to use their DSL connection to establish a VPN link for voice connectivity using an IP phone. My question is, are there any Cisco IP phones with embedded VPN client?

3) Are 3rd party analog voice gateways supported with CME?

Any assistance would be greatly appreciated!

[paolo bevilacqua]

Answer to 1 and 2 is yes.

Answer to 3 is not officially, with the exeception of some GSM gateways.

[Asad Raza]

Hi Paolo,

Thanks for your reply. That was very helpful.

So how exactly would redundancy be accomplished since there are no CAC mechanisms in CME?

Also, since the teleworkers will be connecting the the CME over a DSL link, are there any other VPN solutions apart from using an IP phone with an embedded VPN client, such as creating a VPN link between the DSL router and the CME rouer automatically whenever a call is established?

Thanks!

[paolo bevilacqua]

The dial-peer architecture is very powerful and allows many things to be done. Once you have the exact requirements, that can be discussed in more details.

For VPN, the best choice is to place a cisco router at teleworker residence. That will provide a strong, permament VPN for the phone and the PCs.

Thanks, for the nice rating and good luck!

[Asad Raza]

Thanks Paolo. I guess my questions is, since the IP phones will be registering with a single CME IP address, can we load-balance between the two CMEs using HSRP (which will use a single logical IP address). Then, the active CME can use itself or the other CME router as the gateway for outside calling (preferrably in a round-robin fashion). Does this sound plausible?

The customer may be unwilling to use a Cisco router at the telecommuter's residence (due to cost), in which case they may use a 3rd party DSL router. Can we provide them with an IP phone (such as the 7945) that will establish a VPN session over the DSL with their firewall or the CME router (with the appropriate security bundles for VPN sessions), where the entire operation is transparent to the telecommuter user? If so, could you provide some documentation on how this may be accomplished?

Again, your help is much appreciated, and you're welcome (for the rating)!

[paolo bevilacqua]

No you will not user HSRP for load balancing calls. Only dial-peer configuration.

The best choice for VPN teleworkers is using small cisco router like 851 or 857. If really pressed for price, use something from the small business product line. All other methods have noticeable disavantages and I would not recommedn them