ZyXEL Communications Prestige 480 - Manual (Page 81)

Prestige 480 Dual BRI ISDN Router
Internet Access 3-17
At this point, your Prestige will ask if you wish to test the Internet connection. If you select Yes, the Prestige
will call the ISP and test the configuration. If the test fails, note the error messages on the screen and take the
appropriate troubleshooting steps.
3.8 Mega Bundle or Multiple ISPs Support
3.8.1 Basics
If ISPs do not support multilink bundle of more than 2 links, it would be impossible for a user to dedicate all
4 channels available in a P 480 to Internet access. To differentiate P 480 from other similarly equipped
products, it is desirable to be able to support bundle of 4 links where P 480 calls a second ISP when the
traffic exceeds a certain threshold and split the traffic between the two connections. The Prestige refers to
this multiple ISPs support as Mega Bundle.
Mega Bundle design is as listed below.
1. One remote node is designated as the main ISP and another the supplementary ISP. The Prestige dials
the first and second link on the main ISP using the existing mechanism.
2. If a supplementary remote node is specified, BOD behalves as if the maximum number of channels is 4
and the adding and dropping of channels are governed by the main remote node’s multilink parameters
alone.
3. When the traffic triggers t he third link (as determined by BOD), the Prestige calls the supplementary
ISP. Since the new connection is a separate PPP session, it will have a different IP address and thus a
new interface.
4. Because of NAT, if an IP connection is already assigned to a particular interface, then it must remain on
that interface. For new connections, the round-robin method is used to assign a connection to either the
main or the supplementary ISP. Non-IP traffic is simply distributed evenly on a packet-by-packet basis.
5. Once the Prestige determines which interface a connection uses, the MP channel assignment within each
bundle remains the same as the existing method.