3Com CoreBuilder 9000, User Manual

Page: 334 / 468

334 C
HAPTER
12: E-IISP P
ROTOCOL
IISP vs. E-IISP
The IISP routing protocol is a simple, universal protocol used to connect
the CoreBuilder 9000 ATM Enterprise Switch to ATM switches of other
vendors.
IISP (PNNI phase 0) is the first phase standard for multiple switch
networks. This protocol defines the routing decision/algorithm according
to a
static database. You create the database manually via management
and build it in a hierarchical structure. The routing decision is based upon
address matching, full or partial, using the best match method.
With IISP, routing decisions are made on a switch-by-switch basis. One
switch sends a request for an SVC to another, and the receiving switch
searches its address table for the destination address. The request is
passed on to another switch in the network if the destination address is
found. This procedure is repeated until the call reaches its destination.
You specify the IISP for individual ports using the Local Management
Application (LMA). You configure the ATM address prefix in a IISP port
using the Add Address command of the LMA. (For more information, see
“Add ATM Address to Port” on page 141.) Using this command, set the
prefix to the ATM address of the switch that is connected to that port, as
well as any ATM addresses beyond that switch. Include the ATM prefix of
switches connected in some way to that switch to allow connectivity to
them or to a device that is attached to them.
The ATM address prefix can be a full 13-byte prefix or partial prefix with
an asterisk (*) to mark the end of the significant bytes, and allows tree
hierarchical definition from the tree-top without listing all the prefixes of
this tree.
IISP does not provide for any method of route calculation across the ATM
network. Instead, manual routing tables have to be entered in by the
network administrator. 3Com enhanced this routing protocol to allow
for autodiscovery of the ATM switch peers in a network. When using
E-IISP (with 3Com equipment), an ATM switch can determine the address
of its neighbor switch without any intervention by the network
administrator.