3Com 3C421600A, Management Manual

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Using FCP to Bridge with OfficeConnect Routers
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FCP supports the following features:
■
Data compression
■
Multilink line aggregation (Multilink FCP)
PPP Versus FCP
PPP is used widely throughout the IP community to connect routers from
different manufacturers. It is recognized as the de facto standard protocol
for this purpose. PPP can be used over both wide area network (WAN)
and ISDN links. When using PPP, both ends of the link must be configured
to use PPP.
While PPP is very flexible in terms of configuration, it is not as efficient in
terms of speed of connection or throughput as FCP. However, if you need
to connect to the Internet or to another manufacturer's router you will
need to configure the unit to use PPP.
How FCP Works
The following steps demonstrate how FCP works:
1 The RAS 1500 established the LAPB link as a part of the FCP negotiation.
2 Both sides of the link exchange Names and MAC addresses, negotiate
compression (STAC), and reset the sequence numbers.
3 The RAS 1500 prepends data packets with a 2-byte sequence number.
a If you have a routed link, the routed packets are first prepended with a
Ethernet MAC Header and then with the 2 byte sequence number.
b If you have a bridged link, the bridged packets already carry a MAC
Header so only the 2 byte sequence number is prepended.
4 The RAS 1500 passes data packets to the LAPB link.
An FCP link idles out if traffic on the link falls to configured idle threshold
for the configured Idle period.
Configuring the RAS 1500 for FCP
Use the following steps to configure the RAS 1500 for FCP:
1 Define a modem group:
add modem_group 12 inter rm0/mod:[1-2]
2 Define the network settings:
a Add the FCP user to the network:
add user [username] type network,dial_out network fcp
enable no