3Com CoreBuilder 7000, Operation Manual, Page: 70 / 264

70 C
HAPTER
4: P
RIVATE
N
ETWORK
-
TO
-N
ETWORK
I
NTERFACE
(PNNI) V
ERSION
1.0
Figure 15
Looping in e-IISP
This figure shows a sample network topology, in which the signal is sent
as follows:
Switch E is transmitting to Switch A.
The signal is sent from E to C (see number 1 in Figure 15).
The link from switch C to A goes down (as indicated by an “X”).
Switch C knows that the link is down. It cannot send the message
back to Switch E, so it sends the signal to Switch D (see number 2).
Source
Destination
A
C
E
B
D
F
X
1
2
3
4