Virtual Private Cloud OnDemand Networking Guide

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Translated (Internal) IP/Range: 10.0.0.2
This NAT example shows the translation of IP addresses on the private network on the inside of the
gateway. When the virtual machine at 10.0.0.2 sends a packet to the Web server at 209.165.200.225, the
virtual machine’s real address (10.0.0.2) is translated to 209.165.200.1. When the Web server responds, it
sends the response to IP address 209.165.200.1, and the gateway translates 209.165.200.1 back to the real
address 10.0.0.2 before sending it to the virtual machine.
You can configure NAT rules to create a private IP address space inside Virtual Private Cloud OnDemand
to port your private IP address space from your enterprise in to the cloud. Configuring NAT rules in
Virtual Private Cloud OnDemand allows you to use the same private IP addresses for your virtual machines
in Virtual Private Cloud OnDemand that are used in your local data center.
NAT rules in Virtual Private Cloud OnDemand include the following support:
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Creating subnets within the private IP address space
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Creating multiple private IP address spaces for a gateway
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Configuring multiple NAT rules on multiple gateway interfaces
IMPORTANT By default, gateways are deployed with firewall rules configured to deny all network traffic to
and from the virtual machines on the routed networks. Also, NAT is disabled by default so that gateways
are unable to translate the IP addresses of the incoming and outgoing traffic. You must configure both
firewall and NAT rules on a gateway for the virtual machines on a routed network to be accessible.
Attempting to ping a virtual machine on a network after configuring a NAT rule will fail without adding a
firewall rule to allow the corresponding traffic.
Related Information
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See “Add a NAT Rule,” on page 23 in this guide for the steps to create a SNAT or DNAT rule
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See “Add a Firewall Rule,” on page 29 in this guide for the steps to create a firewall rule.
DHCP
To change the default behavior for DHCP in Virtual Private Cloud OnDemand networks, you edit the
DHCP service settings in vCloud Director.
When you create a network in Virtual Private Cloud OnDemand, DHCP is configured for
Virtual Private Cloud OnDemand in the following ways.
Routed Network
DHCP is configured for routed networks in the following ways:
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Disabled by default.
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When you create a virtual machine and add it to a routed network, you must explicitly set its IP address
unless you have enabled DHCP for that network.
Configure DHCP for a routed network by navigating from Virtual Private Cloud OnDemand to the
networking services for the gateway in vCloud Director:
Virtual Private Cloud OnDemand Web UI > Gateway tab > Manage in vCloud Director > vCloud Director
Administration page > Edge Gateways tab > select the gateway, right-click and choose Edge Gateway
Services > DHCP tab
Enable and configure DHCP for a routed network to automatically assign an IP address to a virtual machine
when it is added to a routed network. The virtual machine gets assigned an IP address based on the DHCP
parameters configured.
vCloud Air - Virtual Private Cloud OnDemand Networking Guide
14 VMware, Inc.