Van Jacobson: pathchar - a new tool for characterizing Internet paths
I would be interested in such a Debian package when the software
described below becomes available. Perhaps it could be added to its
brethren in netstd?
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Subject: pathchar - a new tool for characterizing Internet paths
From: van@ee.lbl.gov (Van Jacobson)
Date: 21 Apr 1997 08:59:38 -0500
Newsgroups: info.ietf
For the past 6 years, I've been working on a tool to figure out
more about an Internet path that just what routers you go through.
I've developed a tool called `pathchar' (for `path characteristics')
that tells you the bandwidth, distance from previous hop, average
queue, and drop rate for every hop on the path (*not* just the
bottleneck hop). This is a typical output:
% pathchar ka9q.ampr.org
mtu limitted to 1500 bytes at local host
doing 32 probes at each of 64 to 1500 by 32
0 localhost
| 8.7 Mb/s, 292 us (1.97 ms)
1 ir40gw.lbl.gov (131.243.1.1)
| 29 Mb/s, 132 us (2.64 ms)
2 er1gw.lbl.gov (131.243.128.11)
| 91 Mb/s, 189 us (3.15 ms)
3 lbl-lc1-1.es.net (198.128.16.11)
| 25 Mb/s, 6.92 ms (17.5 ms)
4 gac-atms.es.net (134.55.24.6)
| 11 Mb/s, 424 us (19.4 ms)
5 CERFNETGWY.GAT.COM (192.73.7.163)
| 7.0 Mb/s, 1.20 ms (23.5 ms)
6 sdsc-ga.cerf.net (134.24.20.15)
| ?? b/s, -263 us (22.8 ms)
7 mobydick-fddi.cerf.net (134.24.252.3)
| 46 Mb/s, -51 us (22.9 ms)
8 qualcomm-sdsc-ds3.cerf.net (134.24.47.200)
| 9.0 Mb/s, 17 us (24.3 ms)
9 krypton-e2.qualcomm.com (192.35.156.2)
| 5.5 Mb/s, 1.04 ms (28.6 ms)
10 ascend-max.qualcomm.com (129.46.54.31)
| 56.7 Kb/s, 6.19 ms (253 ms)
11 karnp50.qualcomm.com (129.46.90.33)
| 10 Mb/s, -50 us (253 ms), +q 3.32 ms (6.58 KB) *2
12 unix.ka9q.ampr.org (129.46.90.35)
rtt 32 ms (253 ms), bottleneck 56.7 Kb/s, pipe 4706 bytes
The lines starting with `|' are the characteristics of the link
between the hops listed above & below. The first number is the
link bandwidth, the 2nd is the one-way prop time (i.e., for a
zero length packet) & the number in parens is the round trip
time you would get if there were no queues and you sent a
path-mtu sized packet from the source to this hop (i.e., the
unloaded data rtt). If there's a queue larger than 1 packet,
its size in both time & bytes is printed. If the drop rate is
more than 1%, it's printed.
Note that it successfully found the LBL FDDI dmz (hops 2-3) &
SDSC-Qualcomm T3 (hops 7-8) even though I was running it behind
a 10Mb/s ethernet. And that the long hop from San Francisco to
San Diego is clearly visible (3-4). (Also note that I was
running this at 1am this morning so the normal cerfnet queues
were missing & only Phil's P50 ISDN box showed a queue.)
We're hoping to release pathchar sometime in the next two weeks.
I'm giving a talk on it today at 4pm PDT for MSRI Math Awareness
Week and the talk should be mboned. I've put the viewgraphs
from the talk (which are the only existing documentation) at
ftp://ftp.ee.lbl.gov/pathchar/msri-talk.ps.gz
If you really deperately want to play with a very flakey, alpha
version of pathchar, there are binaries for freebsd, linux and
solaris in the same directory (but you are totally on your own
when running this -- we'll answer questions once the beta release
goes out but right now we're putting all our energy into getting
it out).
Cheers.
- Van
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