Experience(s) with Enhanced SRST vs. Traditional SRST? - Page 2

crescentwire · ‎02-14-2012

Hi everyone,

We are looking to gain more insight into the advantages/differences of using Enhanced SRST for remote site survivability in the event of a WAN outage, vs. the more traditional SRST that many of us know and have worked with for quite some time. I know the end-user experience is supposed to be a little more robust and tailored, but beyond that, what are the real benefits?

Also, if anyone can explain their setup, hardware-wise and deployment specifics, as to how their Enhanced SRST setup is configured, I'd appreciate it. I've received a lot of conflicting information about what exactly is needed for an Enhanced SRST deployment, so any information you can provide me here is greatly appreciated.

Thanks very much for your time.

crescentwire · ‎02-15-2012

Just to be clear:

UMG for SRSV and VPIM is being EOS'ed
UMG for E-SRST is NOT being EOS'ed
UMG is required for E-SRST
A CME-SRST remote office gateway router is NOT required for E-SRST, but the licensing IS required (that is, a standard C2951-VSEC/K9 gateway coudl be used)

Correct?

Chris Deren · ‎02-15-2012

Correct on first 3 points.

For last point the hardware for CME-SRST is the local gateway and no different from traditional SRST, licenses for CME-SRST are inter-changable with traditional SRST. They are not enforced today but you need to purchase them to be entitled to use the feature.

HTH,

Chris

rgates · ‎03-20-2012

How is the branch office user experience different? (I had thought E-SRST was actually a rebranded Marketing term for CME-as-SRST. Reading through this thread indicates that is not the case. It sounds like CME-as-SRST is yet-another-option.

So, in a centralized delployment with a CUCM cluster at the main campus, (co-located with a Unity Connection cluster) as well as all of the PSTN gateways and a small ISR router at the branch office (with a couple of POTS) my options are:

SRST for basic failover, so branch phones can place 911 calls, etc, through the branch office PSTN.
E-SRST for 'enhanced' failover, so branch phones get same line appearances etc, as if they could still reach CUCM.
CME-as-SRST. -- how does it compare to E-SRST?

Or more specifically, if the IP WAN to the branch office fails, and the client is good with routing inbound calls from the PSTN campus GW to Unity Connection until the IP WAN to the branch office comes back up... what should I do?

E-SRST at the branch (with SCCP branch office phones and a UMG located at the campus)
CME-as-SRST at the branch (configured for dynamic registration so the branch phone brings it's current config to the CME-as-SRST. (which allows me to deploy SIP phones to the branch too & doesn't require a UMG at the campus.)

Please help!

Chris Deren · ‎03-20-2012

Correct, E-SRST is different from CME as SRST as explained in previous posts.

E-SRST requires centralized management via UMG module, CME as SRST is basic standalone configuration on the router where you define telephony-service instead of call-manager-fallback and which give you additional options/features you do not get with basic SRST, basically you are running CME as SRST failover.

>>Or more specifically, if the IP WAN to the branch office fails, and the client is good with routing inbound calls from the PSTN campus GW to Unity Connection until the IP WAN to the branch office comes back up... what should I do?

Are your trunks centralized and inboud calls arrive via central site? If so any feature is feasible as it does not make a difference here, if you want them to go to VM they will by default, if you want to re-route the calls through PSTN to the remote site you will need to use forward on unregistered setting on the DNs, either solution has nothing to do with what you do as SRST.

HTH,

Chris

rgates · ‎03-29-2012

Thanks Chris. Can you please clarify...

Do they both offer the same telephony features? I have heard that you can configure CME-as-SRST to allow phones to dynamically register (and bring their current phone configuration in the event of an IP WAN failure at the branch site). Does it mean that each phone/line need to be preconfigured? From what I had heard, the answer was no. I understood the dynamic piece was that the phone 'brought it's lines/speed dials, etc. with it, when it reregistered with the CME-as-SRST device. If that feature exists, and works, as described here, why would I ever run E-SRST and pay for an additional UMG device?

Rob

Chris Deren · ‎04-02-2012

Robbie,

Sorry for late reply as I was out on vacation, the big advantage of Enhanced SRST is that it brings a lot more information from CUCM/UMG when phone registers with CME/SRST as normal SRST or CME as SRST, for example it defines cor-list based on CSS/PT configuration in CUCM, etc. The idea is that now SRST is fully synchronized with CUCM and you do not have to maintain it separately.

HTH,

Chris