12
Chapter 1
Troubleshooting Methodology
Inside-out Troubleshooting
The second method is to start near the user and work your way toward Host
Z, otherwise known as the
inside-out troubleshooting
method. Figure 1.7
contains a diagram that describes this testing method. You see that the
user can FTP to machines within the same network, but can't FTP to any
machine on the Campus B network. The steps are marked by the Xs, with the
step number in parentheses.
F I G U R E 1 . 7
Starting from the inside and working out
Using the second method saved you one step--three instead of four. Sta-
tistically, however, you isolate the boundary with fewer steps by using the
first method. The important thing is that the boundary be established.
Campus A
Frame
relay
cloud
Campus B
FDDI
ring
Host B
Host C
Host D
Host F
Host G
Host E
Host H
Host J
Host K
Host I
Host L
Host X
Host Y
Host W
Host Z
Host A
VLAN 1
FTP OK
Local (1)
(3)
(2)
VLAN 1
VLAN 3
VLAN 2
1. FTP local OK
2. No FTP between
Host A and and host
on Campus B
3. No FTP between
Host A and Host Z
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