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CUCM or E-SRST for a site having 300 users

mtaneja712
Level 1
Level 1

Hi,

We already have CUCM PUB/SUB installed at our HQ and now we are coming up with a new branch site having 250-300 users approx. The latency between HQ and branch site is around 50ms on VPN tunnel and in future, we are planning to set an MPLS link between HQ and branch site.

My question is whether to deploy a CUCM SUB node at branch site or to setup a local router with E-SRST at branch site with all branch site phones registering to HQ CUCM SUB and why? Also what the factors that will help in deciding SUB or E-SRST?

Thanks,

Mohit

5 Replies 5

Brandon Buffin
VIP Alumni
VIP Alumni

Mohit,

Here are a few things to consider:

  1. Will you have a local gateway at this site for PSTN access? If so, the incremental cost to add SRST would be significantly less than adding a subscriber.
  2. Remote upgrades are more difficult, take longer and happen more frequently for a subscriber than for a router running SRST.
  3. Will you have other sites like this? If so, the remote subscriber model is less scalable than SRST as there is a limit of 8 call processing subscribers in a cluster.
  4. Is bandwidth between the locations sufficient? 300 phones registering back to the HQ will require some bandwidth. Also, how many simultaneous calls do you expect between the locations? You will need to consider these factors when sizing the circuit.

Brandon

Hi Brandon,

1. Yes, we will deploy a local PSTN gateway at that site.

3. We don't have other sites like this. Few remote office with head count of 30-40 users and for them we will leverage expressways

4. The bandwidth between HQ and branch site is 80 Meg

I have few questions :

1. We already have enhanced workspace licenses. Can you how SUB will be costlier than E-SRST ?

2. What are the cons of using ESRST ? 

3. If we choose SRST 10.5 , do we need a UMG or SRST Manager or both ?

4. Can E-SRST router and SRST manager be deployed at different sites over WAN. I mean I am thinking of installing SRST manager in HQ and router will be at branch site?

5. We have VMware ESXi 5.5 host with Processor Type AMD Opteron Processor 6380. Does SRST Manage or CUCM Virtual machines support this processor type?

Thanks, 

Mohit 

1. From a cost perspective, the hardware for an additional subscriber would be more than utilizing an existing gateway to run SRST. Even if the gateway is not existing, you will need to purchase either way.

2. SRST does not have all of the features of CUCM.

3. You can use SRST manager, but it is not necessary. Especially for one site.

4. Yes

5. http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/uc_system/virtualization/collaboration-virtualization-hardware.html

1. If SRST manager is not present then how data sync between CUCM and E-SRST ISR would work?

2. SUB will be virtual,  I am not sure how that would add to hardware cost since we already have ESXi servers at the branch site. And also we have the enhanced workspace licenses. Does install a SUB requires a node license as well ??

3. I don't think AMD processors aren't supported with UC apps. http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/uc_system/virtualization/collaboration-virtualization-hardware.html#processor

Can you please confirm?

Regards,

Mohit

1. Without SRST manager you would need to add the configuration manually and make changes manually. With a small number of sites and relatively few changes this should not be a problem. Large scale deployment would benefit greatly from SRST manager.

2. Yes, you will need a node license. If the subscriber is virtual this license would be the only additional cost.

3. Correct. See below.

"Other CPU vendors such as AMD are not supported for UC."

http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/uc_system/virtualization/collaboration-virtualization-hardware.html#processor

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