Single Domain with Split DNS - Recommended
A single domain means that you have a common domain (example.com) with separate internal and external DNS servers. This allows DNS names to be resolved differently by clients on different
networks depending on DNS configuration, and aligns with basic Jabber service discovery requirements.
Dual Domain without Split DNS
From X12.5, the Cisco Expressway Series supports the case where MRA clients use an external domain to lookup the _collab-edge SRV record, and the _cisco-uds SRV record for that same external domain cannot be resolved by the Expressway-C. This is typically the case when split DNS
is not available for the external domain. And prior to X12.5 this required a pinpoint subdomain or some other DNS workaround
on the Expressway-C, to satisfy the client requirements for resolving the _cisco-uds record.
Limitation: This case is not supported for Unified CM nodes identified by IP addresses, only for FQDNs.
This feature also supports a secondary case, for MRA deployments that only allow Jabber access over MRA even if users are
working on-premises. In this case only one domain is required and typically the DNS records are publicly resolvable (although
this is not required if MRA access is disallowed for users when off premises). The change in X12.5 means that there is no
need to have a _cisco-uds._tcp.<external-domain> DNS SRV record available to Cisco Expressway-C or to the Jabber clients.
Single Domain without Split DNS
Deployments that require Jabber clients to always connect over MRA also benefit from the X12.5 update that no longer requires the Expressway-C to resolve
the _cisco-uds DNS SRV record. So administrators only need to configure the _collab-edge DNS SRV record, and Jabber clients using service discovery will only have the option of connecting over MRA.
URL for Cisco Meeting Server Web Proxy and MRA domain cannot be the same
If you use both the CMS Web Proxy service and MRA on the same Expressway, the following configuration items must be assigned
different values per service. If you try to use the same value, the service that was configured first will work, but the other
one will fail:
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MRA domain(s). The domain(s) configured on Expressway and enabled for Unified CM registration
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CMS Web Proxy URL link. Defined in the Expressway "Guest account client URI" setting on the Expressway > Configuration > Unified Communications > Cisco Meeting Server page.
Multiple External Domains for Mobile and Remote Access
Cisco Expressway supports Mobile and Remote Access with multiple external domains. With this deployment, you will have more
than one external domain where your MRA clients may reside. Expressway-E must be able to connect to all of them. To configure
this deployment, do the following:
For Expressway-E:
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On Expressway-E, configure _collab-edge._tls.<domain> and _sips_tcp.<domain>DNS SRV records for each Edge domain.
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Configure A records that point the Expressway-E hostname to the public IP address of Expressway-E.
For Expressway-C:
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For internal DNS, add A and PTR records that point to Expressway-E FQDN. Add these records to all Expressway-C nodes.
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Configure the _cisco_uds SRV record for every domain to point to your Unified Communications Manager clusters.
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On the Domains page of Expressway-C, add each of the internal domains that point to the Unified Communications Manager cluster.
For more detail, including a configuration checklist that summarizes the domain-specific configuration tasks for multiple
domains, see Multidomain Configuration Summary.