christos@dworkin.wustl.edu (Chris Papadopoulos) (11/14/90)
Let me first introduce myself. I am Christos Papadopoulos, a graduate
student at Washington Univ working with Guru Parulkar. I am interested
in remote visualization. I plan to implement an application which we
think has characteristics typical of visualization applications and
distribute it across our campus network using TCP/IP. Then tap in the
protocols at different levels and take various measurements to
identify where the bottlenecks are (if any).
The application we picked is "Display of cell trajectories in 3D
using Optical Sectioning Microscopy". This uses an optical microscope
equipped with a CCD camera to collect images of planes in an organism.
The big advantage of this method is that there is no physical slicing
involved, thus the organism does not have to be killed. The CCD camera
has variable pixel resolution of up to 1000 by 1000, at 4096 graylevels.
The volumetric data will be in the range of 10-20 MBytes per image. To
trace the trajectories of cells several images need to be collected to
construct a short animation. There is a number of steps that need to be
performed before the data can be rendered. These include elimination of
noise due to the point spread function of the lens, edge enhancement,
image segmentation and various geometric transformations.
After distributing the application we would like to monitor the
communication and take measurements on protocol overhead. The
communication model we think may be appropriate is as follows:
TCPq Networkq Networkq TCPq
-------- ----| ----| ----| ----| ----------
|Sender|-----> |||-----> |||----------> |||-----> |||----->|Receiver|
-------- ----| ----| Ethernet ----| ----| ----------
The measurements we would like to take include:
(i) Dynamic queue length at the various queues
(ii) Various delays a packet experiences
The question I want to ask is the following:
Are there probe and measurement utility programs which will allow us
to take these measurements without any kernel modifications?
Thanks in advance,
Christos.0004219666@MCIMAIL.COM (Bob Stine) (11/14/90)
>... I plan to implement an application which we think has characteristics >typical of visualization applications ...[t]hen tap in the protocols at >different levels and take various measurements to identify where the >bottlenecks are (if any). > ... > The measurements we would like to take include: > (i) Dynamic queue length at the various queues > (ii) Various delays a packet experiences > ... > >Are there probe and measurement utility programs which will allow us >to take these measurements without any kernel modifications? Christos, You might check RFC 1147, "A Network Management Tool Catalog," for a list of several tools. Unfortunately, to the best of my recollection, the only tools capable of monitoring actual queue lengths require some (well-documented) kernel mods. I could be wrong about this. My gut feeling, however, is that getting the queue lengths will require some special instrumentation, which in turn will require kernel mods. At any rate, I recommend that you take a look at the catalog entry describing NETMON and iptrace, developed by Allison Mankin, of MITRE. NETMON is essentially kernel instrumentation for BSD-UNIX. You might conclude that avoiding mods to the kernel is not a hard-and-fast requirement. For background on TCP/IP, I'd also recommend that you read RFC 1122, "Requirements for Internet hosts -- communication layers." - Bob Stine