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LARTC: trace control for netem

Rainer Baumann netdev 1 version In review

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Cover letter [PATCH 2.6.16.19 0/2] LARTC: trace control for netem

This is the revised trace extension to the network emulator netem. This extension provides emulation control based on pregenerated traces.

We first submitted this patch on 2nd of August, in the mean time we integrated the comments from Stephen and fixed the listed things.

Cheers,
Rainer

-------- Original Message --------
Subject: Re: [PATCH 2.6.16.19 0/2] LARTC: trace control for netem
Date: Wed, 2 Aug 2006 11:19:21 -0700
From: Stephen Hemminger <[email protected]>
To: Rainer Baumann <[email protected]>
CC: [email protected], [email protected]
References: <[email protected]>

Quoted 61 lines

On Wed, 02 Aug 2006 19:21:27 +0200

Quoted 60 lines
Quoted 27 lines · Rainer Baumann
Quoted 27 lines

Hi,

We developed an extension to the network emulator netem, that provides emulation of long term network properties such as long-range dependence and self-similarity of cross-traffic. It is not possible to emulate these properties with the statistical tables for the packet delay values used by the original netem.

We read the values for the packet delay, drop, loss and corruption from a pre-generated trace file. This trace file is obtained by monitoring network traffic and writing all actions to a trace file. During the emulation the packets get processed according the values in such a trace file. Detailed information are available on our Webseitehttp://tcn.hypert.net

A new option (trace) has been added to the netem command. If the trace option is used, the values for packet delay etc. are read from a trace file, afterwards the packets are processed by the normal netem functions. The packet action values are readout from the trace file in user space and sent to kernel space via procfs.

The evaluation results show similar behavior for our enhancement and the original netem with respect to packet delay precision and packet loss at high load (e.g. 80'000 packets per second).
It is possible to add, change or delete multiple netem qdiscs on-the-fly (original netem qdiscs and trace qdiscs mixed).

Quoted 5 lines
Quoted 5 lines

We are looking forward for any comments, feedback and suggestions!

Thanks,
Rainer

I like the idea and want to get it incorporated.

Major things that need fixing:
* Don't extend size of tc_netem_qopt instead use a new netlink payload.
+ add type to TCA_NETEM_ enum
+ new structure containing the payload
This allows for binary compatiablity.

* Don't use proc for a interface to netem features. Use netlink. Either add a new command (or option) to the iproute2 commands to handle flow table, or add a new payload.

Minor stuff:
* the bzero macro in netem is a BSDism, just use memset
* bad indentation and style issues.
* minor whitespace damage in several places in patch

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Read the cover letter in its thread