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).
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.
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.
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).
DHCP Server
The DHCP server provides host, IP gateway, DNS server, and NTP server addresses to endpoints located on the internal
network.
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).
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.
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
and mobile worker registering to Unified CM across the internet and 3
rd
party businesses making calls to, or receiving
calls from this network).
The Expressway-E is configured with a traversal server zone to receive communications from the Expressway-C in order
to allow inbound and outbound calls to traverse the NAT device.
to allow inbound and outbound calls to traverse the NAT device.
The Expressway-E has a public network domain name. For example, the Expressway-E is configured with an externally
resolvable name of expe.example.com (which resolves to an IP address of 192.0.2.2 by the external / public DNS
servers).
resolvable name of expe.example.com (which resolves to an IP address of 192.0.2.2 by the external / public DNS
servers).
4
Cisco Expressway-E and Expressway-C - Basic Configuration Deployment Guide