The netstat(TC) program is helpful in tracking down network malfunctions. In particular, use the following options:
Use the netstat -a command to display active connections and
sockets. Look for phantom connections --
those that still appear as active in the display that were
terminated abnormally. If many appear, your network may run slowly, and
you may need to stop and restart TCP/IP to flush the connections.
The netstat -i command displays active interfaces (network card and serial interfaces) as well as statistics on:
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll net0 1500 10.0.118 don 1348 12 1854 23 65 lo0 8232 loopback localhost 4058 0 4058 0 0In using netstat -i, you should verify that the card is receiving and sending packets (that
Opktsare nonzero), and that input and output errors as well as collisions are a small percentage of the packet total.
Ierrs are zero, the connection
to the network may be bad, the network card may be bad, or there may be
an interrupt vector conflict. Verify network cabling, then check for
interrupt conflicts by running hwconfig or vectorsinuse.
If a conflict exists, use the
Network Configuration Manager
to reconfigure your card. If the cable and interrupt vectors check out, run
any diagnostic tools supplied by the manufacturer of the networking card.
Ipkts is zero, but
Ierrs is nonzero, the network,
cabling, or card may be bad, another host on the network may be
generating bad packets, or the network may be incorrectly terminated.
Opkts is zero and
Oerrs is nonzero, there
may be a conflict of I/O addresses on the system. If both
are zero, the conflict may be in shared memory addresses. Verify
the I/O and shared memory addresses of each card on your
system, and reconfigure your networking card with other supported
addresses if conflicts exist.
Coll is high (greater than 1-2 percent of the
total), your network is very busy. Consider breaking the network into
multiple separate networks.
Use the netstat -m command to monitor streams usage. The display shows each type of buffer allocated; the number free, allocated, and configured; the number of failures per type; and other streams information.
Streams are dynamically allocated in this release of TCP/IP, so streams errors should be uncommon. However, if you notice streams failures and need to reconfigure streams allocation, do so by using configure(ADM).
The netstat -r command provides information about the usage of each route configured on your system. A route consists of a destination host or network and a network interface used to exchange packets. Direct routes are created for each interface attached to the local host.
At a minimum, your routing table should display entries for the loopback
localhost), the local network, the local hostname,
and the IP Multicasting route,
224. The following is a
Routing tables Destination Gateway Flags Refs Use Interface localhost localhost UH 24 66 lo0 10.0.118 nile UC 1 0 net0 nile localhost UGHS 3 36 lo0 224 nile UCS 0 0 net0The columns display: