[cisco-voip] Redundancy Options for CME

[Nick Matthews]

It doesn't look like there is an explicit document that explains this.

This is about as close as I could find:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/command/reference/cme_i1ht.html#wp1012400

It's basically an SRST CME router of sorts.  The phones only register
to the secondary address (which is defined the same on both routers)
when the primary fails.

-nick

On Sun, Jul 12, 2009 at 6:06 PM, Bill Greenwood
(US)<bill.greenwood at us.didata.com> wrote:
> Nick,
>
> Can you provide the link to the documentation that explains?
>
> Bill
>
> -----Original Message-----
> From: matthn at gmail.com [mailto:matthn at gmail.com] On Behalf Of Nick Matthews
> Sent: Sunday, July 12, 2009 5:28 PM
> To: Lelio Fulgenzi
> Cc: Bill Greenwood (US); cisco-voip at puck.nether.net
> Subject: Re: [cisco-voip] Redundancy Options for CME
>
> The primary configuration is:
>
> telephony-service
> ip source-address <cme1> secondary <cme2>
>
> You configure this same thing on both routers.
>
> Then, you configure the h323 dial peers as discussed for routing the
> PRIs when a call comes into the secondary CME.
>
>
> -nick
>
>
>
> On Sun, Jul 12, 2009 at 4:31 PM, Lelio Fulgenzi<lelio at uoguelph.ca> wrote:
>> In a perfect world, yes. However, depending on how your L2/L3 links are set
>> up, it may be possible from some phones to register on each router.
>> Definitely not ideal, and it should be avoided, however, it might be
>> possible. With a dial peer on each router, you cover this scenario.
>>
>> HSRP is really only used to advertise to the phones where to register.
>> Everything else is configured with the appropriate router address, most
>> likely a loopback address. So, it's conceivable that the two routers can
>> talk to each other via L3 via some advertised route, but not via L2 (over
>> which HSRP is handshaked), in that case, each router will advertise it is
>> the HSRP active router.
>>
>> That's just me and my "try to cover every scenario possible" attitude. It's
>> helped me out in some cases, bitten me on the ascot tie others. ;)
>>
>> Then again, I don't try to be an L2/L3 expert and have been known to be
>> laughed out of a network meeting trying to accomodate a scenario that costs
>> 10K to provision and will happen once every election of a pope (that one
>> sounds better in Italian). ;)
>>
>>
>>
>>
>>
>> ---
>> Lelio Fulgenzi, B.A.
>> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
>> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> "Bad grammar makes me [sic]" - Tshirt
>>
>>
>> ----- Original Message -----
>> From: "Bill Greenwood (US)" <bill.greenwood at us.didata.com>
>> To: cisco-voip at puck.nether.net
>> Sent: Sunday, July 12, 2009 4:20:02 PM GMT -05:00 US/Canada Eastern
>> Subject: Re: [cisco-voip] Redundancy Options for CME
>>
>> Thinking more about this:
>>
>>
>>
>> If both routers run CME, on the standby router a general dial peer for the
>> phones would point to the primary router.  This dial peer would not be
>> needed on the primary router as if it was up it would have the phone
>> registered locally.  This dial peer on the standby router would be in place
>> all the time routing calls from the PSTN to the primary router under normal
>> operation.  In the case where the primary router has failed then the phones
>> would register and create more specific dial peers which would route the
>> call locally to the phones.  Does that sound correct?
>>
>>
>>
>> Bill
>>
>>
>>
>> From: Lelio Fulgenzi [mailto:lelio at uoguelph.ca]
>> Sent: Sunday, July 12, 2009 4:03 PM
>> To: Bill Greenwood (US)
>> Cc: cisco-voip at puck.nether.net
>> Subject: Re: [cisco-voip] Redundancy Options for CME
>>
>>
>>
>> Each router would have dial-peers pointing to the other router for each set.
>> There is a default setting (in SRST anyways) that prevents a routing loop
>> via H323.
>>
>> I had a similar question, and it was discussed briefly on the list. One of
>> the Cisco folk told me about the routing loop prevention. That's key.
>> Because it's on by default, it helps.
>>
>> Here's a press release talking about it (in very general terms).
>>
>> http://www.cisco.com/en/US/prod/collateral/routers/ps5854/prod_case_study0900aecd80424090_ns431_Networking_Solutions_Case_Study.html
>>
>>
>> ---
>> Lelio Fulgenzi, B.A.
>> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
>> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> "Bad grammar makes me [sic]" - Tshirt
>>
>>
>> ----- Original Message -----
>> From: "Bill Greenwood (US)" <bill.greenwood at us.didata.com>
>> To: cisco-voip at puck.nether.net
>> Sent: Sunday, July 12, 2009 3:43:39 PM GMT -05:00 US/Canada Eastern
>> Subject: Re: [cisco-voip] Redundancy Options for CME
>>
>>
>> Even if the configurations are synchronized which would allow for the phones
>> to register with either router, how would the calls from the PSTN be
>> handled?  If a call was received on the router that was not the primary it
>> would see the phone as not being registered and forward to voice mail.
>> There needs to be some method of having the routers communicate with each
>> other similar to a publisher and subscriber.  I have not been able to find
>> anything to allow for this communication.  Can the second router be
>> configured with SRST?  But that still leave the question on the PRIs, if
>> both are connected to the primary router and it fails then you are left with
>> no connection to the PSTN.
>>
>>
>>
>> From: mthompson729 at gmail.com [mailto:mthompson729 at gmail.com]
>> Sent: Sunday, July 12, 2009 3:11 PM
>> To: Bill Greenwood (US)
>> Subject: Re: [cisco-voip] Redundancy Options for CME
>>
>>
>>
>> I've never tried to do this, but the only way I could think to do this is
>> using HSRP on the FE interface. this is assuming that the HSRP address can
>> be used as the source-address for the CME system.
>>
>> This would make proper documentation and config sync a critical process
>> though.
>>
>>
>>
>> On Jul 12, 2009 3:03pm, "Bill Greenwood (US)" <bill.greenwood at us.didata.com>
>> wrote:
>>
>>>
>>>
>>> I am looking for information on how to provide redundancy for a CME based
>>> system.
>>> The configuration is there are two identical routers at the
>>> site, two PRI circuits to the PSTN and 60 or so phones.  I am at a loss as
>>> to how to recommend redundancy for this.  Is it one router configured with
>>> CME as normal, but how should the second router be configured?  Is the
>>> second router configured with CME or as an SRST router.  How should the
>>> second router appear to the primary CME router?  How should the PRIs be
>>> connected, if one is connected to each router I can set up the dial peer
>>> to
>>> route the outbound calls, but how are the inbound (from the PSTN) routed?
>>> If the PRIs are connected to only one router redundancy is lost.  I have
>>> be unable to locate any documentation that explains how to set this up.
>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Thanks for your help.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Bill
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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