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Figure 10.7. A Basic Traffic Shaping Scenario
The reason for using 2 different pipes in this case, is that these are easier to match to the physical
link capacity. This is especially true with asynchronous links such as ADSL.
First, two pipes called in-pipe and out-pipe need to be created with the following parameters:
Pipe Name Min Prec Def Prec Max Prec Grouping Net size Pipe limit
in-pipe 0 0 7 PerDestIP 24 1000kb
out-pipe 0 0 7 PerSrcIP 24 1000kb
Dynamic Balancing should be enabled for both pipes. Instead of PerDestIP and PerSrcIP we could
have used PerDestNet and PerSrcNet if there were several networks on the inside.
The next step is to create the following Pipe Rule which will force traffic to flow through the pipes.
Rule
Name
Forward
Pipes
Return
Pipes
Source
Interface
Source
Network
Destination
Interface
Destination
Network
Selected
Service
all_1mbps out-pipe in-pipe lan lannet wan all-nets all
The rule will force all traffic to the default precedence level and the pipes will limit total traffic to
their 1 Mbps limit. Having Dynamic Balancing enabled on the pipes means that all users will be
allocated a fair share of this capacity.
Using Several Precedences
We now extend the above example by allocating priorities to different kinds of traffic accessing the
Internet from a headquarters office.
Lets assume we have a symmetric 2/2 Mbps link to the Internet. We will allocate descending
priorities and traffic requirements to the following users:
• Priority 6 - VoIP (500 kpbs)
• Priority 4 - Citrix (250 kpbs)
• Priority 2 - Other traffic (1000 kpbs)
• Priority 0 - Web plus remaining from other levels
To implement this scheme, we can use the in-pipe and out-pipe. We first enter the Pipe Limits for
each pipe. These limits correspond to the list above and are:
• Priority 6 - 500
• Priority 4 - 250
• Priority 2 - 1000
Now create the Pipe Rules:
Rule
Name
Forward
Pipes
Return
Pipes
Source
Interface
Source
Network
Dest
Interface
Dest
Network
Selected
Service
Prece
dence
web_surf out-pipe in-pipe lan lannet wan all-nets http_all 0
10.1.10. More Pipe Examples Chapter 10. Traffic Management
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