There are two reasons to use L2TP to connect in to AAISP:
#As a back up for your existing AAISP circuit in the even of a fault, using L2TP you can use another ISP to connect in to AAISP and have your normal IP addresses etc whilst your AAISP connection is fixed. Ask staff to set this up.
#Connect in to AAISP over a third-party internet connection. This gives you your an AAISP IPv4 address and an IPv6 block.