What is packet shaping?

[J3anyus]

Okay, so I've been at college for a few days now, and I keep getting told by people to watch out for whether or not my college is doing any packet shaping. Nobody's really explained what the hell it is, they've just said that it's a bad thing and I better hope my university isn't doing it. Can someone explain to me what it is, what it does, how it works, etc.? I'd really appreciate it so maybe I can understand why people are telling me it's bad and if it's something I even care about.

Thanks.

- Jacob

 

[Garion]

Packet shaping is when an active network device prioritizes traffic by type - i.e., normal web traffic gets priority 2, and Kazaa gets priority 5. If the Internet connection gets congested, traffic gets sent out by priority, not by first-come first serve. Packet shapers can also allocate bandwidth to certain applications. i.e., general web browsing gets 30Mb/s and Kazaa 3Mb/s.

- G

 

[ScottMac]

Basically, it classifies the content of the packet, then assigns it a certain priority or bandwidth limit based on that classification.

For example (and I'm sure this is what your friends are talking about), they look in the packet, detect that it's a Kazaa packet, and discard it because the college/university has decided it doesn't want Kazaa traffic on its network. Or it finds other P2P traffic, and allows it, but only gives it 16k MAX ... no matter how much bandwidth you feed it (of P2P), it gets "shaped" down to 16k ... after the buffers fill, the traffic drops.

The people setting up the classification determines the amount of bandwidth to assign the class. You can't get around it ... even if you proxy, encapsulate, or change the port number, it gets classified ... the packet shaper looks into the packet for signature byte patterns and acts on those signatures to assign the class.

In a nutshell, it's policy enforcement. Learn to live with it. Trying to get around it may cost you your privileges on the network.

FWIW

Scott

 

[J3anyus]

Meh, doesn't bother me, I would never install Kazaa or any of that crap anyway. I don't feel like giving hackers and viruses a nice open door to my computer. Thanks for the detailed replies, both of you

 

[jonmullen]

Originally posted by: ScottMac
Basically, it classifies the content of the packet, then assigns it a certain priority or bandwidth limit based on that classification.

For example (and I'm sure this is what your friends are talking about), they look in the packet, detect that it's a Kazaa packet, and discard it because the college/university has decided it doesn't want Kazaa traffic on its network. Or it finds other P2P traffic, and allows it, but only gives it 16k MAX ... no matter how much bandwidth you feed it (of P2P), it gets "shaped" down to 16k ... after the buffers fill, the traffic drops.

The people setting up the classification determines the amount of bandwidth to assign the class. You can't get around it ... even if you proxy, encapsulate, or change the port number, it gets classified ... the packet shaper looks into the packet for signature byte patterns and acts on those signatures to assign the class.

In a nutshell, it's policy enforcement. Learn to live with it. Trying to get around it may cost you your privileges on the network.

FWIW

Scott

Thats only if they are doing level 7 classification. Although it is more and more common its more likely that they are getting classidied based on port. That is why some of the smarter incarnations of P2P will try tunneling through 80 and see if the get better speed. Either way what Scott said still counts dont spend your time trying to get around it. The rules are there for the best of every one and your just being a d!ck if you think you deserve special treatment.

Sidenote: Correct me if I am wrong Scott, but aside from some Cisco stuff I though layer 7 was pretty new to linux/unix. Last time I dealt with it you had to have a beta 2.5.x kernel and I ended up giving up since I could not get every thing to complie and play nicely...maybe things have changed in the last few months.

 

[spidey07]

packeteer packetshapers are awesome. We've got a couple and they knock any P2P and messenger traffic to 5 Kbit. No matter what port.

they really are intelligent and can identify traffic based on application and not by port. real slick.

www.packeteer.com

I highly recommend them to universities on a regular basis to keep the rugrats from filling up the pipe.

 

[n0cmonkey]

Originally posted by: jonmullen

Originally posted by: ScottMac
Basically, it classifies the content of the packet, then assigns it a certain priority or bandwidth limit based on that classification.

For example (and I'm sure this is what your friends are talking about), they look in the packet, detect that it's a Kazaa packet, and discard it because the college/university has decided it doesn't want Kazaa traffic on its network. Or it finds other P2P traffic, and allows it, but only gives it 16k MAX ... no matter how much bandwidth you feed it (of P2P), it gets "shaped" down to 16k ... after the buffers fill, the traffic drops.

The people setting up the classification determines the amount of bandwidth to assign the class. You can't get around it ... even if you proxy, encapsulate, or change the port number, it gets classified ... the packet shaper looks into the packet for signature byte patterns and acts on those signatures to assign the class.

In a nutshell, it's policy enforcement. Learn to live with it. Trying to get around it may cost you your privileges on the network.

FWIW

Scott

Thats only if they are doing level 7 classification. Although it is more and more common its more likely that they are getting classidied based on port. That is why some of the smarter incarnations of P2P will try tunneling through 80 and see if the get better speed. Either way what Scott said still counts dont spend your time trying to get around it. The rules are there for the best of every one and your just being a d!ck if you think you deserve special treatment.

Sidenote: Correct me if I am wrong Scott, but aside from some Cisco stuff I though layer 7 was pretty new to linux/unix. Last time I dealt with it you had to have a beta 2.5.x kernel and I ended up giving up since I could not get every thing to complie and play nicely...maybe things have changed in the last few months.

I don't know about the rest of it, but I am pretty sure 2.5 is starting to stabilize. You might have more luck with it now, or if you wait a couple of months (heh) you might be able to try and brand spanking new 2.6.0! :Q