ForeRunner
ATM Switch Network Configuration Manual
2 - 3
Confi
guring
Clas
sic
a
l
IP
Configuring Classical IP
2.1.3 SPANS Interface
While each of the Classical IP interfaces for a given physical interface is designed to support
Classical IP using Q.2931 signalling, a SPANS interface also exists for each physical interface.
The SPANS interface is
asx0
in switch software and is
fa0
in host adapter software.
The SPANS interface supports FORE IP on top of SPANS signalling. FORE IP allows commu-
nication using AAL4 or AAL5 with no encapsulation, uses a broadcast ARP for SPANS
address resolution, and supports direct communication of all hosts on a physical ATM net-
work without the use of IP routers. Since SPANS and Q.2931 signalling use different VCIs, a
host can simultaneously support FORE IP over SPANS as well as Classical IP over Q.2931 on
the same physical interface.
As a result of standard IP routing, all traffic sent out a SPANS interface uses FORE IP, while all
traffic sent out a Classical IP interface uses Classical IP. The Classical IP interfaces are
qaaX
(where X is 0 - 3) in switch software and are
ci
in host adapter software.
Each of the SPANS interfaces should be assigned an IP address on a subnet different than the
subnets of any of the Classical IP interfaces. It is permissible to place multiple SPANS inter-
faces on the same subnet, and the driver load balances connections across these interfaces.
It is only necessary to configure the SPANS and Classical IP interfaces if the specific service
provided by that interface is required. A host sending only Classical IP would not need to con-
figure the SPANS interfaces. Likewise, a host sending only FORE IP would not need to config-
ure the Classical IP interfaces. Both the SPANS and Classical IP interfaces may be configured
simultaneously, but they must be in separate subnets. Remember that Classical IP specific con-
figuration changes can only be done with the Classical IP devices, while SPANS specific con-
figuration changes can only be done with the SPANS devices.
Summary of Contents for forerunner series
Page 6: ......
Page 16: ...TOC 10 ForeRunner ATM Switch Network Configuration Manual Table of Contents ...
Page 20: ...LOF 4 ForeRunner ATM Switch Network Configuration Manual List of Figures ...
Page 22: ...LOT 2 ForeRunner ATM Switch Network Configuration Manual List of Tables ...
Page 30: ...viii ForeRunner ATM Switch Network Configuration Manual Preface ...
Page 144: ...3 58 ForeRunner ATM Switch Network Configuration Manual Configuring an Emulated LAN ...
Page 180: ...6 12 ForeRunner ATM Switch Network Configuration Manual ATM Forum PNNI ...
Page 220: ...9 6 ForeRunner ATM Switch Network Configuration Manual Configuring Timing ...
Page 300: ...D 24 ForeRunner ATM Switch Network Configuration Manual Configuring FramePlus Modules ...
Page 308: ...Acronyms 8 ForeRunner ATM Switch Network Configuration Manual Acronyms ...
Page 346: ...Glossary 38 ForeRunner ATM Switch Network Configuration Manual Glossary ...
Page 352: ...Index 6 ForeRunner ATM Switch Network Configuration Manual Index ...