Cisco Cisco Expressway Maintenance Manual
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If the Expressway-E is in the DMZ, the outside IP address of the Expressway-E must be a public IP address, or
if static NAT mode is enabled, the static NAT address must be publicly accessible.
if static NAT mode is enabled, the static NAT address must be publicly accessible.
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The Expressway-E may also be used to traverse internal firewalls within an enterprise. In this case the
"public" IP address may not be publicly accessible, but is an IP address accessible to other parts of the
enterprise.
"public" IP address may not be publicly accessible, but is an IP address accessible to other parts of the
enterprise.
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If you need to change the IP addresses on one or both interfaces, you can do it via the UI or the CLI. You can
change both at the same time if required, and the new addresses take effect after a restart.
change both at the same time if required, and the new addresses take effect after a restart.
Configuring Static NAT
You can deploy the Expressway-E behind a static NAT device, allowing it to have separate public and private IP
addresses. This feature is intended for use in deployments where the Expressway-E is located in a DMZ, and has the
Advanced Networking feature enabled.
addresses. This feature is intended for use in deployments where the Expressway-E is located in a DMZ, and has the
Advanced Networking feature enabled.
In these deployments, the externally-facing LAN port has static NAT enabled in order to use both a private and public
IPv4 address; the internally facing LAN port does not have static NAT enabled and uses a single IPv4 (or IPv6)
address.
IPv4 address; the internally facing LAN port does not have static NAT enabled and uses a single IPv4 (or IPv6)
address.
In such a deployment, traversal clients should be configured to use the internally-facing IP address of the
Expressway-E.
Expressway-E.
To enable the use of a static NAT:
1.
Ensure that the Advanced Networking option key is installed.
2.
For the externally-facing LAN port:
a.
In the IPv4 address field, enter the Expressway-E's private IP address.
b.
Set IPv4 static NAT mode to On.
c.
In the IPv4 static NAT address field, enter the Expressway-E's public IP address - this is the IP address of
the outside of the NAT.
the outside of the NAT.
Note:
The combination of having static NAT mode on and having the B2BUA engaged to do media
encryption/decryption can cause the firewall outside the Expressway-E to mistrust packets originating from the
Expressway-E. You can work around this by configuring the firewall to allow NAT reflection. If your firewall cannot
allow this, you must configure the traversal path such that the B2BUA on the Expressway-E is not engaged.
Expressway-E. You can work around this by configuring the firewall to allow NAT reflection. If your firewall cannot
allow this, you must configure the traversal path such that the B2BUA on the Expressway-E is not engaged.
Configuring DNS Settings
The DNS page (System > DNS) is used to configure the Expressway's DNS servers and DNS settings.
Configuring the System Host Name and Domain Name
The System host name defines the DNS host name that this Expressway is known by.
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It must be unique for each peer in a cluster.
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It is used to identify the Expressway on a remote log server (a default name of "TANDBERG" is used if the
System host name is not specified).
System host name is not specified).
The Domain name is used when attempting to resolve unqualified server addresses (for example
ldapserver
). It is
appended to the unqualified server address before the query is sent to the DNS server. If the server address is fully
qualified (for example
qualified (for example
ldapserver.mydomain.com
) or is in the form of an IP address, the domain name is not appended
to the server address before querying the DNS server.
It applies to the following configuration settings in the Expressway:
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LDAP server
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NTP server
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Cisco Expressway Administrator Guide