Datasheet

Cisco Preferred Architecture for
Midmarket Collaboration PAGE 28
Collaboration Edge
Cisco Expressway-E
Because Expressway-E is reachable directly from the untrusted, external network, it should be placed in a DMZ for
security. The organization’s firewall policies control communications to and from this server. Deploy Expressway-E to:
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Function as a traversal server and allow secure communications to and from Expressway-C
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Enable audio and video connections to other organizations using SIP or H.323 on the Internet
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Provide secure communications to cloud-based services, such as CMR Cloud to the WebEx cloud
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Provide DNS SRV lookup service to resolve outbound calls and to receive inbound calls over the Internet
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Process registration and IM and presence information from Cisco endpoints on the external network and use secure
traversal communications to pass the information to Expressway-C
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Provide interworking between protocols (between SIP and H.323, and between IPv4 and IPv6) for business-to-
business communications
Licensing
Cisco Expressway can be used for mobile and remote access with no additional investment. However, if business-to-
business calling is enabled, Rich Media licenses are required. Each business-to-business call requires two Rich Media
licenses. License Cisco Expressway for the anticipated maximum concurrent business-to-business sessions.
Connectivity for Audio and Video over the Internet
URI dialing is the best practice for audio and video dialing over the Internet. Cisco recommends assigning alphanumeric
URIs to all devices that will send or receive calls over the Internet. Any device on Cisco Unified CM can be reached over
the Internet by dialing the assigned alphanumeric SIP URI or the required directory number (DN) by dialing <+E.164
number>@domain. For example, a Jabber user might have a SIP URI set to [e-mail] and a phone number set
to [phone]. If someone dials [e-mail] or [e-mail] from an external location on the
Internet, Alice would receive the call on the Jabber client and all devices that share the same number.
Users on Cisco Unified CM have to dial the full SIP URI to reach a user or device from a different organization over
the Internet.
The architecture for business-to-business Internet connectivity includes a client/server solution: Expressway-C and
Expressway-E. Both servers can be deployed in standalone mode or in a cluster. Deploy the same number of cluster
peers for Expressway-C clusters as for Expressway-E clusters.
Cisco recommends deploying dedicated Expressway-C and Expressway-E clusters per customer-chosen Internet
breakout to minimize having outbound business-to-business calls traverse the WAN by routing them, instead, to an
Internet breakout close to the client that initiated the call. This minimizes the business-to-business call-related utilization of
the enterprise WAN.
Considerations for Outbound Business-to-Business Calls
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When multiple Expressway-C and Expressway-E pairs are deployed, Unified CM can redirect an outbound call to
the edge server that is nearest to the calling endpoint, thus minimizing WAN traffic.
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For call routing over the Internet, use public DNS service records. DNS SRV records map a domain to an edge
system servicing that domain for that protocol. For example, if a remote user dials [e-mail], then the
remote system uses DNS to query for the host offering the SIP service for the domain ent-pa.com.