Technical data

Troubleshooting Techniques and Tools
1.2 Isolating Problems
1.2.4 Examining Network Statistics
Use the netstat utility or the SHOW INTERFACE command to check interface
and protocol statistics, per-connection status, and memory buffer use. Look for
bad checksums, excessive retransmissions, dropped packets, out-of-order packets,
and lost-carrier errors.
For example:
TCPIP> netstat -i
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll
TN0* 1280 Link Link#2 0 0 0 0 0
WF0 4470 Link 00:00:f8:cd:1e:e4 48855499 0 2035244 0 0
WF0 4470 16.20 ucxaxp 48855499 0 2035244 0 0
LO0 4096 Link Link#1 165084 0 165084 0 0
LO0 4096 127 LOCALHOST 165084 0 165084 0 0
Some problems to look for are:
• If the output of the netstat -i command shows excessive amounts of input
errors (Ierrs), output errors (Oerrs), or collisions (Coll), this may indicate a
network problem; for example, cables may not be connected properly or the
Ethernet may be saturated.
• The netstat -m command shows statistics for network-related data
structures. Use this command to determine if the network is using an
excessive amount of memory in proportion to the number of sockets in use.
• The netstat -an displays allocated sockets (each socket results in a network
connection).
The following example shows the output of the
netstat -m command:
TCPIP> netstat -m
1328 mbufs in use:
2 mbufs allocated to data
2 mbufs allocated to ancillary data
139 mbufs allocated to socket structures !
244 mbufs allocated to protocol control blocks "
442 mbufs allocated to routing table entries
2 mbufs allocated to socket names and addresses
26 mbufs allocated to interface addresses
1 mbufs allocated to ip multicast options
2 mbufs allocated to ip multicast addresses
5 mbufs allocated to interface multicast addresses
48 mbufs allocated to NFS request header
1 mbufs allocated to vnode struct
32 mbufs allocated to kern credential data structure
2 mbufs allocated to mbuf extra-data protocol message
58 mbufs allocated to assorted NFS structures
6 mbufs allocated to network interface structure
2 mbufs allocated to netisr thread queues
5 mbufs allocated to Inet PCB queues
1 mbufs allocated to rad specific structures
1 mbufs allocated to OpenVMS Cluster Alias table
37 mbufs allocated to OpenVMS Kernel VCI structure
12 mbufs allocated to OpenVMS TCPIP Timer structure
3 mbufs allocated to OpenVMS LAN VCI VCIB structure
3 mbufs allocated to OpenVMS LAN MCAST_REQ structure
12 mbufs allocated to OpenVMS SELECT structure
1 mbufs allocated to OpenVMS ACP Filter Buffer
1 mbufs allocated to OpenVMS ACP AQB
1 mbufs allocated to OpenVMS ACP INETCB
2 mbufs allocated to OpenVMS Driver requested REQCB
26 mbufs allocated to OpenVMS ACP allocated SERV Structure
Troubleshooting Techniques and Tools 1–7