Cisco Cisco Expressway
Network elements
Internal network elements
The internal network elements are devices which are hosted on the organization’s local area network.
Elements on the internal network have an internal network domain name. This internal network domain name
is not resolvable by a public DNS. For example, the Expressway-C is configured with an internally resolvable
name of expc.internal-domain.net (which resolves to an IP address of 10.0.0.2 by the internal DNS servers).
is not resolvable by a public DNS. For example, the Expressway-C is configured with an internally resolvable
name of expc.internal-domain.net (which resolves to an IP address of 10.0.0.2 by the internal DNS servers).
Expressway-C
The Expressway-C is a SIP Proxy and communications gateway for Unified CM.
The Expressway-C is configured with a traversal client zone to communicate with the Expressway-E to
allow inbound and outbound calls to traverse the NAT device.
allow inbound and outbound calls to traverse the NAT device.
EX90 and EX60
These are example endpoints hosted on the internal network which register to Unified CM.
Note that endpoints or other devices cannot register to the Expressway. Registration requests will be
rejected and will be logged with 'License limit exceeded' messages.
rejected and will be logged with 'License limit exceeded' messages.
DNS (local 1 & local 2)
DNS servers used by the Expressway-C, to perform DNS lookups (resolve network names on the internal
network).
network).
DHCP server
The DHCP server provides host, IP gateway, DNS server, and NTP server addresses to endpoints located
on the internal network.
on the internal network.
Router
The router device acts as the gateway for all internal network devices to route towards the DMZ (to the NAT
device internal address).
device internal address).
Unified CM
Endpoint devices register to Unified CM and the Expressway acts as a Unified Communications gateway for
third-party devices and to provide mobile and remote access.
third-party devices and to provide mobile and remote access.
.
Syslog server
).
DMZ network element
Expressway-E
The Expressway-E is a SIP Proxy for devices which are located outside the internal network (for example,
home users and mobile worker registering to Unified CM across the internet and 3
home users and mobile worker registering to Unified CM across the internet and 3
rd
party businesses making
calls to, or receiving calls from this network).
Cisco Expressway Basic Configuration Deployment Guide (X8.6)
Page 6 of 57
Introduction