Citrix NetScaler EE, Руководство по установке и настройке

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Deployment Modes
Jan 28, 2011
A SD-WAN appliance acts as a virtual gateway. It is neither a TCP endpoint nor a router. Like any gateway, its job is to
buffer incoming packets and put them onto the outgoing link at the right speed. This packet forwarding can be done in
different ways, such as inline mode, virtual inline mode. Although these methods are called
modes
, you do not have to
disable one forwarding mode to enable another. If your deployment supports more than one mode, the mode that the
appliance uses is determined automatically by the Ethernet and IP format of each packet.
Because the appliance supports different forwarding modes and different kinds of non-forwarded connections, it needs a
way of distinguishing one kind of traffic from another. It does so by examining the destination IP address and destination
Ethernet address (MAC address), as shown in table below. For example, in inline mode, the appliance is acting as a bridge.
Unlike other traffic, bridged packets are addressed to a system beyond the appliance, not to the appliance itself. The
address fields contain neither the appliance's IP address nor the appliance's Ethernet MAC address.
In addition to pure forwarding modes, the appliance has to account for additional types of connections, including
management connections to the GUI and the heartbeat signal that passes between members of a high-availability pair. For
completeness, these additional traffic modes are also listed in table below.
T able 1. How Et hernet and IP Addresses Det ermine t he Mode T able 1. How Et hernet and IP Addresses Det ermine t he Mode
Dest inat ion Dest inat ion
IP Address IP Address
Dest inat ion Dest inat ion
Et hernet Et hernet
Address Address
Mode Mode
Not appliance Not appliance Inline or Pass-through
Not appliance Appliance Virtual Inline or L2 WCCP (WAN OP)
Appliance Appliance Direct (UI access)
Appliance (VIP) Appliance High-Availability. Proxy mode
Appliance
(WCCP GRE
Packet) Appliance WCCP GRE Mode
Appliance
(Signaling IP) Appliance Signaling Connection (SD-WAN plugin Signaling Connection (SD-WAN plugin,
Secure Peer) or Redirector Mode Connection (SD-WAN plugin)
All modes can be active simultaneously. The mode used for a given packet is determined by the Ethernet and IP headers.
The forwarding modes are:
Inline mode, Inline mode, in which the appliance transparently accelerates traffic flowing between its two Ethernet ports. In this
mode, the appliance appears (to the rest of the network) to be an Ethernet bridge. Inline mode is recommended,
because it requires the least configuration.
WCCP mode (WAN OP),
WCCP mode (WAN OP), which uses the WCCP v. 2.0 protocol to communicate with the router. This mode is easy to
configure on most routers. WCCP has two variants: WCCP-GRE and WCCP-L2. WCCP-GRE encapsulates the WCCP