Problem Solving:Internet
max (in most implementations of
supports fewer than nine hops, which
combinations of Windows NT and
Traceroute this defaults to 30 hops but
is a very small number for external
specific (namely Cisco) router BIOS in
can be changed by using the m flag).
Internet probes (although it may be
terfaces. These problems have now all
Three probes (which can also be
perfectly suitable for internal network
been eliminated, except for a specific
modified by using the q flag) are di
diagnosis). Traceroute's record route
problem regarding TTL shrouds or
rected towards each TTL setting and
flag (or r argument) to ping remote
packet blocking daemons from Spam
the TTL address of the gateway and the
hosts is faster. It doesn't, however, re
mer sites that try to remain anonymous.
round trip time of each probe is re
turn response statistics for the various
When a user is experiencing prob
turned.
legs of the journey and it is not totally
lems, it is best to ask them to use Trac
If the Traceroute responses come
reliable.
eroute from his or her terminal rather
from different gateways, the address
from your login or terminal (if you
of each responding system will be re
Results
reside on a different part of the net
turned. However, if there's no re
work). This is because you will need to
sponse within a timeout interval
Traceroute is a diagnostic tool that
eliminate router problems from within
(normally three seconds but this can be
can safely be issued by your users when
your own network before assuming
modified via the w flag), an asterisk is
they are experiencing network prob
the fault lies with someone else's rout
displayed for that particular probe.
lems (for example, when a particular
ers outside the network.
There are alternative ways to use
Web page is unusually slow to down
Most of the common problems are
ICMP packets to perform a very simi
load). Some early implementations of
delays caused by an overloaded server
lar function, but ICMP normally only
Traceroute did not work with certain
(too many users fighting for the same
aggregated port address). The ICMP
packets used by Traceroute are han
Tracing route to www.dancingfox.com [208.197.253.130] over a maximum of 30 hops:
dled within the TCP/IP network code
1 298 ms 327 ms 330 ms ipt fo2.proxy.aol.com [205.188.198.95]
on the Web server. Because of this, the
2 368 ms 438 ms 329 ms tot wj dr4r.proxy.aol.com [205.188.198.124]
3 362 ms 328 ms 382 ms tpopd rri1.red.aol.com [205.188.128.57]
server's OS can still process ICMP effi
4 310 ms 329 ms 411 ms tpopd rre1 P5 0.red.aol.com [205.188.128.1]
ciently even if the server is overloaded
5 366 ms 331 ms 377 ms pos12 0 0.gw1.iad2.alter.net [205.188.128.109]
with disk read requests or is switching
6 359 ms 321 ms 326 ms 133.ATM2 0.XR1.DCA1.ALTER.NET [146.188.161.194]
7 347 ms 326 ms 382 ms 295.ATM3 0.TR1.DCA1.ALTER.NET [146.188.161.142]
between too many server processes.
8 369 ms 476 ms 391 ms 101.ATM6 0.TR1.SCL1.ALTER.NET [146.188.136.222]
Many users assume that a request to
9 356 ms 433 ms 382 ms 299.ATM7 0.XR1.SFO4.ALTER.NET [146.188.146.77]
download a Web page establishes
10 418 ms 434 ms 434 ms 191.ATM8 0 0.GW3.SFO1.ALTER.NET [146.188.145.229]
11 409 ms 416 ms 399 ms earthlink oak gw.customer.ALTER.NET [137.39.166.2]
some sort of two way communication
12 538 ms 549 ms 369 ms 208.197.248.18
channel with its server. Traceroute's
13 464 ms 420 ms 381 ms www.dancingfox.com [208.197.253.130]
output reinforces that notion to many
Trace complete.
users by listing a series of routers as it
hops between the sending worksta
tion and its destination. However this
Figure 2 Output from TRACERT WWW.DANCINGFOX.COM.
is not exactly the case.
Figure 3 Cyberkit in action.
Figure 4 Back with a different provider.
File: P1815.2
Issue 101 (November 1998) page 4
PC Network Advisor
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