Avocent Access Router Cyclades-PR2000 - Manual (Page 109)

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Cyclades-PR2000
Chapter 12 - Filters and Rules
An example showing the third type of traffic control is given in Figure 12.8. The network administrator wants to
prioritize the access to his web server. He also wants to prioritize e-mail sent by his SMTP server, but the
priority should be lower. All other traffic should have the lowest priority. For web server access, the important
flow direction is not the user requests, but rather the data requested. The traffic control rule must be placed on
link 2. In the case of e-mail, the important flow is the data leaving the e-mail server, and not the
acknowledgements back. This is also governed by link 2. (Note: flow control could be placed on the data
request packets and the SMTP acknowledgements by associating rules to link 1.)
Web Server
E-mail Server
Web Client
E-mail Server
PR2000
Requests
ACKs
Back
Data
Requested
E-mail
out
Port: 80
Port: 25 (SMTP)
Port: Any
Link 2
Link 1
Port: Any
INTERNET
FIGURE 12.9 TRAFFIC RULE EXAMPLE 2