Cisco Cisco Expressway
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.
Expressway-C in order 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).
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).
External network elements
Jabber
An example remote endpoint, which is registering over the internet to Unified CM via the Expressway-E and
Expressway-C.
Expressway-C.
DNS (Host)
The DNS owned by service provider which hosts the external domain example.com.
DNS (external 1 & external 2)
The DNS used by the Expressway-E to perform DNS lookups.
NTP server pool
An NTP server pool which provides the clock source used to synchronize both internal and external devices.
NAT devices and firewalls
The example deployment includes:
n
NAT (PAT) device performing port address translation functions for network traffic routed from the internal
network to addresses in the DMZ (and beyond — towards remote destinations on the internet).
network to addresses in the DMZ (and beyond — towards remote destinations on the internet).
n
Firewall device on the public-facing side of the DMZ. This device allows all outbound connections and
inbound connections on specific ports. See
inbound connections on specific ports. See
.
n
Home firewall NAT (PAT) device which performs port address and firewall functions for network traffic
originating from the EX60 device.
originating from the EX60 device.
n
with a static NAT and Dual Network Interface architecture.
SIP and H.323 domain
The example deployment is configured to route SIP (and H.323) signaling messages for calls made to URIs
which use the domain example.com.
which use the domain example.com.
n
DNS SRV records are configured in the public (external) and local (internal) network DNS server to enable
routing of signaling request messages to the relevant infrastructure elements.
routing of signaling request messages to the relevant infrastructure elements.
n
The internal SIP domain (example.com) is the same as the public DNS name. This enables both registered
and non-registered devices in the public internet to call endpoints registered to the internal infrastructure.
and non-registered devices in the public internet to call endpoints registered to the internal infrastructure.
.
Cisco Expressway Basic Configuration Deployment Guide
Page 7 of 57
Introduction