From: Le Anh Duong (duongla@vnn.vn)
Date: Sat Oct 22 2005 - 08:59:51 GMT-3
Hi group,
I am very confused with the solution of ATM part, lab 3. Pls help.
Requirement:
Configure the ATM PVCs as shown in Figure 3-12. Use point-to-point
subinterfaces and use the new format PVC vpi/vcConfigure the ATM PVCs as shown
in Figure 3-12. Use point-to-point subinterfaces and use the new format PVC
vpi/vci when configuring the PVCs. Ensure that the ATM subinterfaces contain
purely Layer 2 information, configure virtual Layer 3 addresses elsewhere for
the ATM connectivity, and make this connectivity as secure as possible. This
configuration does not require any form of bridging.
Figure 3-12: R6 atm1/0-------------ATM cloud-------------atm3/0 R5
VPI/VCI: 0/99 for both R6 and R5
(No more any other information)
Solution:
The clues to the question are not configuring Layer 3 and making it secure.
The only way of achieving this is using PPP. ATM is capable of running PPP but
it requires the encapsulation type aal5ciscoppp and the reference to a
virtual-template interface.
My confusion is
1. Why the aal5ciscoppp encapsulation type is "required" ? Why is it not LLC
or MUX encapsulation ?
2. Do we need to map layer 3 (IP address) information to the pvc statically
like in the solution ( I think not because PPP is encapsulated over ATM not
IP):
pvc 0/99
protocol ip a.b.c.d broadcast
Thanks
Duong
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