Re: Webex App (Unified CM) - MRA workload and redundancy questions

etmarcof · ‎03-13-2023

I have one CUCM Cluster distributed between two datacenter´s . Some Webex App users on LAN are primarily registered to CUCM-SUB1A in DC-A and register to CUCM-SUB1B in DC-B if DC-A Fails .Others Webex App users are registered primary in DC-B in CUCM-SUB1B and register to CUCM-SUB1A if DC-B fails

I would like to have this kind of configuration in one Expressway Cluster for Mobile Remote Access (MRA). That is If i have one cluster of Expressway's distributed between same two datacenter´s if a Webex APP user are registered in CUCM of DC-A on LAN should connect first to Expressway-E-A and Expressway-C-A of that DC-A and only if not available go to EXP-E of DC-B. And vice Versa for a Webex APP users registered primarily to CUCM-SUB1B on LAN.

Can i achieve this expressway configuration with with following configuration or do i need to configure two expressway Clusters one for each domain?

1-Configuring two subdomains for Voice Services dca.domain.com and dcb.domain.com and configure the SRV Records on External DNS :

Domain Service Protocol Priority Weight Port Target Host
dc-a.domain.com collab-edge tls 10 10 8443 expressway-e-a.domain.com
dc-a.domain.com collab-edge tls 20 10 8433 expressway-e-b.domain.com

dc-b.domain.com collab-edge tls 10 10 8443 expressway-e-b.domain.com
dc-b.domain.com collab-edge tls 20 10 8443 expressway-e-a.domain.com

2-Configuring configuring SRV Records on Internal DNS :

Domain Service Protocol Priority Weight Port Target Host
dc-a.domain.com cisco-uds tcp 10 10 8443 cucm-sub1a.domain.com
dc-a.domain.com cisco-uds tcp 20 10 8433 cucm-sub1b.domain.com

dc-b.domain.com cisco-uds tcp 10 10 8443 cucm-sub1b.domain.com
dc-b.domain.com cisco-uds tcp 20 10 8443 cucm-sub1a.domain.com

3-On Webex Control Hub create two UC Manager profile for these sub two Service domains and associate to Users according they should go first DC-A or DC-B.

Will this work or am i missing something?

PS: I don't want to use GEO DNS.

Thanks.

MC

Nithin Eluvathingal · ‎03-13-2023

It wont work what you expect with the above configurations. GEO DNS will suite your scenario.

Jonathan Schulenberg · ‎03-13-2023

Expressway clusters should be contained within a single data center. If you have two DCs then you should have two clusters each of Expressway-C and -E. You cannot control the cluster nodes chosen for the Traversal zone. Spreading the clusters across DCs will create diagonal flows, for lack of a better term, between Exp-E and Exp-C; your firewall and InfoSec people will likely frown on it. If you’re using CUCM Device Mobility this will also blow that feature up.

Also, the entire Voice Services Domain feature is a bandaid; the app shouldn’t need it at all if the user’s email address matches the DNS domain of your SRV records.

If you really don’t want GeoDNS you’re better off putting an Exp-E SEV record per-DC at the same priority each with a weight of 50 to achieve, in theory, a round robin load split.

etmarcof · ‎03-14-2023

Hi @Jonathan Schulenberg , thank you for the inputs!

Just to check if i understood the suggestion is two have one expressway-c and expressway-e cluster per DC. But with one single Voice Service Domain or with two subdomains Voice Services Domain? (Customer don't want use e-mail address domain) I asking because you said ("..you’re better off putting an Exp-E SEV record per-DC at the same priority..") .

Jonathan Schulenberg · ‎03-14-2023

In my previous reply I meant a single domain that matches the user's email address. For example, if the email is example-user@cisco.com the SRV records would be _collab-edge._tls.cisco.com. In that approach you would create an SRV record per Expressway-E but manipulate the priority and weight values to split traffic amongst the data centers.