The network interface
(NI), the software that provides an
interface between a node and a network, specifies the type and maximum
number of links that can be configured for a node. Because a node's
network interface determines what links can be configured for the
node, links are said to be configured underneath network interfaces.
There are nine types of network interfaces (in addition to
loopback):
LAN for IEEE
802.3 and Ethernet networks.
FDDI for fiber optic networks.
100VG-AnyLAN for 100VG-AnyLAN
networks.
100Base-T for 100Base-T networks.
NS over SNA is no longer
offered as a product and has been removed from the Corporate Price
List. The product is obsolete with no plans for support.
Number of Network Interfaces |
 |
A system can have up to 12 network interfaces (NI) configured. One
of these network interfaces must be loopback. For each network interface,
the maximum number of links you can configure and the kinds of links
possible are determined by the network interface type, as follows:
A LAN network interface can have only
one link configured under it; however, a single link can reach a
large number of nodes. ThickLAN cable supports up to 100 nodes per
segment; ThinLAN cable can be used for up to 30 nodes per segment;
and each Ethertwist 3000/iX can be used for up to 50 nodes. Up
to two LAN NIs can be active at a time per system.
A Token Ring interface can have only one link configured
under it; however, a single link can reach a large number of nodes.
Token Ring 3000/iX Network Link can support up to 250 nodes per
ring using shielded twisted pair (STP) cabling at 4 or 16 Mbps and
50 nodes per ring using unshielded twisted pair (UTP) cabling at
4 Mbps.
Only one Token Ring NI can be active at a time per system.
An FDDI interface can have only one link configured
under it; however, a single link can reach a large number of nodes.
FDDI/iX Network Link can support up to 1000 nodes. Up
to four FDDI NIs can be active at a time per system.
A Point-to-Point network interface can have up to
40 links configured under it. Point-to-Point links may be dial links
, in which a
modem attached to a node is used to transmit and receive data carried
across telephone wires, or leased lines, in which data is sent over data-grade
lines leased from a private carrier. Up to 11 Point-to-Point
NI's can be active at a time (one NI must be loopback) for a total
of 12 NI's per system.
An X.25 network interface can have from one to 11
links configured, depending on the number of configured X.25 network
interfaces on the node. (A single node can have up to 11 NIs and
up to 11 X.25 links.) Each link can be connected to as many as 1,024
remote nodes, with communication allowed with as many as 256 nodes
at the same time. Up to 11 X.25 NI's can be active at
a time (one NI must be loopback) for a total of 12 NI's per system.
A gateway half network interface can have only one
link configured under it (the gateway half link). Links connecting
two gateway halves can be only NS Point-to-Point 3000/iX Network
links. Only one gateway half NI can be active at a time
per system.
If more than one (non-loopback) network interface is configured
on a node, the network portions of the IP addresses configured for
the interfaces should differ to correspond to the multiple networks
to which the node belongs.
Refer to "Software Configuration Maximums"
at the end of this chapter for information on configuration path
maximums.
Priority of Network Interfaces |
|
If it is possible to reach a destination through more than
one active NI, the network determines which NI to select according
to the following priority:
| loopback |
| 100VG-AnyLAN |
| 100BASE-T |
| FDDI |
| LAN |
| Token Ring |
| X.25 |
| Gateway Half |
| Point-to-Point (router) |
If more than one NI of a given type is active, (for example,
two X.25 NIs) the network will select the one that it finds first.
