Priorities And Guarantees; The Eight Pipe Precedences - D-Link NetDefend DFL-210 User Manual

10.1.5. Priorities and Guarantees

Now that we have the pipe defined, what do we do with it? Well, first we will need to set up a rule
that covers surfing and place it before the rule that covers "everything else". This way we can get
surfing traffic to go through the specific pipes that we want it to, but still let everything else be
handled by the "default" pipes we created earlier.
Copy the forward chain settings from the rule covering all "Standard" protocols.
Now, we'll have to figure out how to pass the return traffic through the "surf-in" pipe that we
defined.
First, passing the surf traffic through the "surf-in" pipe in the return chain would seem a good
enough idea, so let's start by doing that.
However, unfortunately, this will likely not get you the desired effect.
You will now have inbound traffic passing through two pipes: one that will forward 256 kbps, and
one that will forward 128 kbps, for a total of 384 kbps of inbound traffic.
So, how do we limit the surfing traffic to 128 kbps without upsetting the grand total limits?
Simple: pass the inbound surf traffic through the std-in pipe aswell.
Now, inbound surf traffic will first pass through the "surf-in" pipe, and get limited to 128 kbps.
Then, it will get passed through the "std-in" pipe, along with the rest of the inbound traffic, which
applies the 256 kbps total limit. So, if you're surfing for 128 kbps worth of bandwidth, those 128
kbps will occupy half of the std-in pipe, leaving only 128 kbps for the rest of the traffic, which is
probably more along the lines of what you wanted.
If there is no surfing going on, all of the 256 kbps allowed through the std-in pipe will be available
for all the rest of the traffic.
10.1.5. Priorities and Guarantees
10.1.5.1. Precedences
Each pipe contains eight precedences, or priority levels, numbered from 0 to 7. Each precedence
may be seen as a separate queue where network traffic may be controlled. Precedence 0 is the least
important precedence. Precedence 7 is the most important one.
Figure 10.2. The Eight Pipe Precedences.
Note
This is not a traffic guarantee for web browsing. One could consider it a 128 kbps
traffic guarantee for everything but web browsing, but for web browsing, the normal
rules of first-come, first-served applies when competing for bandwidth. This may mean
128 kbps, but it may also mean the equivalent of a 2400 baud modem if your connec-
tion is sufficiently flooded.
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Chapter 10. Traffic Management