Re: [LARTC] tc/htb QoS script

[Andy Furniss <andy.furniss@dsl.pipex.com>]

Ulrich Pöschl wrote:
> hello folks,
> 
> this is my first post to that list. so I hope I am not completely OT 
> here :-)
> 
> reading the (excellent!) lartc and then writing my own qos-script I have 
> still some open questions which I will try to formulate now:
> 
> - "Now we can optionally attach queuing disciplines to the leaf classes. 
> If none is specified the default is pfifo." - I can't find info about 
> Pfifo. is it the same as pfifo_fast?
> what happenes when I do not add queuing disciplines to the leaf classes? 
> only the filters?

pfifo = packet fifo it's just a first in first out not as clever as 
pfifo fast. If you don't add a queue to a leaf you get a long pfifo - 
limit set by htb rather than you.

> - can a class burst above the ceil-parameter when there is NO other 
> traffic on the line at that moment?

You can specify burst and cburst for htb in your scipt if you want - if 
you don't htb chooses them for you from rate/ceil.

See them with tc -s -d class ls devX.

> 
> - what happens when a packet passing trough the filters can be matched 
> by two filters? f.e. I have a "general" type of WWW-port 80 filter and 
> another WWW-port 80 filter to a certain subnet. is it like a cisco ACL? 
> the first hit is applied?

Yes use prio to order filters and remember 1 is highest not 0.

> 
> - is hardware a criteria? i want to shape a pretty full 2048/2048 line 
> and use an old server with 2 NICs at the moment. 128 MB ram, but gnome 
> running.. :) could I create a bottleneck by doing so?

Probably be OK as long as you don't have thousands of tests per packet.

> 
> 
> - question concerning the script (below):
> it is quite simple. I want to filter any traffic going to an "SAP" 
> subnet. (where we have the SAP-system) and WWW as well as email
> i apply it to interface eth0 and eth1 (which are part of an ethernet 
> bridge br0).
> as there are all servers on one side of the bridge and I want it to be 
> "plug and play"-like I apply the same script to both interfaces.
> 
> The setup is like this:
> [Manchester] (~250 Clients) ---> Transparent QoS-Bridge ----> ROUTER 
> -------- FR WAN 2 Mbit ------> [AT/Vienna] (Mailserver, Proxy, SAP)
> 
> - and: will my script work as expected with that setup? :)
> 
> thanks in advance and kind regards,
> 
> Ulrich
> 
> 
> 
> 
> #!/bin/sh
> #
> ############ Configuration part ##############
>         DEVICE=$1       # interface (eth0 / eth1)
> 
> Bandwidth 48kbit  # rate of WAN - line / remember you can't ceil this 
> or you'll experience latency. 75-80% of ceil is a good place to start.

Your rates and ceils seem to ignore this comment :-)

Remember rates are guaranteed prio only affects sharing of what's spare.

Rest looks OK but I often miss things - test, test, test is the best way.

Andy.

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