Multitech ProxyServer MTPSR3-200, User Manual, Page: 32 / 130

ProxyServer User Guide
MTPSR3-200 32
Dynamic Bandwidth Allocation
The ProxyServer uses a technology called Dynamic Bandwidth Allocation on its WAN ports which
allows users to make use of the maximum bandwidth available during application use. In essence,
this feature allows a single user to access all three WAN ports simultaneously, allowing maximized
bandwidth when using a multiple stream application such as a Web browser. If a single user is
utilizing all three ports, and a second user starts an application, the bandwidth is automatically re-
allocated to share the WAN port resources between the users. For example, if User 1 is running a
Web browser and User 2 starts a Telnet session, one of the WAN ports being used to download Web
content is allocated for the Telnet session. When that session ends, the WAN port is made available
to the Web browser again. All this takes place dynamically, or ‘automatically’ on the ProxyServer.
The examples that follow detail three different application environments that make use of dynamic
bandwidth allocation. The first shows a single user downloading content from the Web. The second
shows three users running various applications. The final example describes a configuration where a
single WAN port is dedicated to a manager and the other two are configured for other users.
Example 1 - Single Workstation Running Web Browser
In this example, a single workstation (IP address 192.168.2.4) is using the ProxyServer with a Web
browser. All three ports are available and each port can download a separate frame, therefore
maximizing efficiency. Since workstation 192.168.2.4 is the only workstation actively using the Proxy,
and is loading a Web page, each WAN port will download a separate frame, simulating a download of
up to 150 Kps, depending on the line conditions.
LINK3 LINK2 LINK1 ETHERNET COMMAND POWER
10BASET 10BASE2
ON
OFF
Internet
Hub
Modem 3
Modem 2
Modem 1
Web Page Elements
MTPSR3-200
Workstation A
Running Web Browser
(IP Address 192.168.2.4)
If at any time another workstation requests bandwidth from the ProxyServer, the ProxyServer will
shift some of the bandwidth to accommodate the requesting application. Once that application is
finished, all bandwidth is re-allocated to the first workstation. For a more detailed description of this
process, refer to Example 2.
Example 2 - Multiple Workstations Running Various Applications
In Example 1 Workstation A (IP address 192.168.2.4) is loading a Web page. Example 2 shows the
bandwidth allocation when two additional workstations request bandwidth from the ProxyServer.
Workstation B (IP address 192.168.2.3) engages an FTP session on WAN 2, and Workstation C (IP
address 192.168.2.2) engages in a Telnet session on WAN 3. Because both the Telnet and FTP
sessions are single-stream applications (unlike the framed, or multiple-stream content of a Web
page) they can only use one WAN port. The amount of bandwidth allocated will depend on the
application and the link. If WAN 2 is connected to an FTP server providing download speeds of 19.2
Kbps, then the Web browser will load its page using WAN 1 (@ 50 Kbps) plus any “leftover”
bandwidth available from WAN 2. The same applies for the Telnet session on WAN 3 - any additional
bandwidth will be allocated for the Web connection.