368 Chapter 10: X.25/Frame Relay Topologies
Table 10-3 contains detailed explanations of specific commands from this chapter that are
important to the CCDP.
HDLC
High-Level Data-Link Control. A bit-oriented synchronous data link layer protocol
developed by ISO. Derived from SDLC, HDLC specifies a data encapsulation method on
synchronous serial links using frame characters and checksums.
Star
(hub
and
spoke)
A LAN topology in which endpoints on a network are connected to a common central switch
by point-to-point links.
Dual
star
A redundant star network with the central sites connected via a common backbone, usually
an Ethernet segment.
ISDN
Integrated Services Digital Network. A communication protocol offered by telephone
companies that permits telephone networks to carry data, voice, and other source traffic.
X.121
An ITU-T standard describing an addressing scheme used in X.25 networks. X.121
addresses are sometimes called IDNs.
Table 10-3
Show Processes
Field
Description
CPU utilization
for five seconds
CPU utilization for the last 5 seconds. The second number indicates the percent of
CPU time spent at the interrupt level.
one minute
CPU utilization for the last minute.
five minutes
CPU utilization for the last 5 minutes.
PID
Process ID.
Q
Process queue priority. Possible values are H (high), M (medium), and L (low).
Ty
Scheduler test. Possible values are * (currently running), E (waiting for an event), S
(ready to run; voluntarily relinquished processor), rd (ready to run; wakeup
conditions have occurred), we (waiting for an event), sa (sleeping until an absolute
time), si (sleeping for a time interval), sp (sleeping for a time interval (alternate
call), st (sleeping until a timer expires), hg (hung; the process will never execute
again), and xx (dead; the process has terminated but has not yet been deleted).
PC
Current program counter.
Runtime (ms)
CPU time the process has used, in milliseconds.
Invoked
Number of times the process has been invoked.
uSecs
Microseconds of CPU time for each process invocation.
Stacks
Low water mark/total stack space available, in bytes.
TTY
Terminal that controls the process.
Table 10-2
Chapter Terms (Continued)
87200333.book Page 368 Wednesday, August 22, 2001 2:53 PM