Displays PEdriver channel information for specific nodes. Each
channel is a single NISCA communications path between a LAN
device on a local system and a LAN device on a remote system.
Use the SHOW CHANNEL command to display node names and local and
remote device names.
Format
SHOW CHANNEL nodename
1 – Parameter
nodename[,...]
Includes channels to specific nodes, which you can use wildcards
to specify. Each node name can be accompanied by optional
qualifiers to specify local and remote device names. If no local
or remote device name is specified, all channels associated with
the specified node name are included.
2 – Qualifiers
2.1 /ALL
Includes all channel data.
2.2 /COUNTERS
Includes channel counters data.
2.3 /ECS
/ECS
/NOECS
Includes only channels that are (or are not) members of the ECS.
2.4 /EXCLUDE
/EXCLUDE=(nodename[,...])
Excludes channels to specific nodes, which you can use wildcards
to specify. Each node name can be accompanied by optional
qualifiers to specify local and remote device names. If no local
or remote device name is specified, all channels associated with
the specified node are included.
2.5 /INTERVAL
For the /COUNTERS display, displays the changes to counters since
the last SHOW command.
2.6 /LOCAL_DEVICE
/LOCAL_DEVICE=(landevicename/IPinterfacename[,...])
Includes specific LAN devices that identify the local end of the
channel; you can use wildcards to specify LAN devices.
Use the SHOW LAN_DEVICE command to display device names.
2.7 /n
Displays the nth page. To select a particular page of a multipage
display, specify the number of the page you want to display.
2.8 /OUTPUT
/OUTPUT=filespec
Creates the specified file and directs output to it.
2.9 /REMOTE_DEVICE
/REMOTE_DEVICE=(landevicename/IPinterfacename[,...])
Includes specific LAN devices/IP interfaces that identify the
remote end of the channel; you can use wildcards to specify LAN
devices/IP interfaces.
Use the SHOW LAN_DEVICE command to display device names.
2.10 /SDA
Includes channel data displayed in SDA format, with all the data
collected in one display for one channel.
2.11 /SUMMARY
Includes channel summary data. This is the default if /ALL,
/COUNTERS, and /SDA qualifiers are not specified.
3 – Examples
1.SCACP> SHOW CHANNEL NODE20/LOCAL=EWA
The command in this example displays channel definition data
for all nodes defined with local device EWA and any remote
device and remote node name starting with NODE20.
2.SCACP> SHOW CHANNEL/COUNTERS/INTERVAL
SCACP> SPAWN WAIT 0:0:10
SCACP> SHOW CHANNEL/COUNTERS/INTERVAL
The first command in this example displays channel counters
since the last SHOW command. The SPAWN command tells the DCL
WAIT command to insert a 10-second delay. The second SHOW
CHANNEL command displays counters after the 10-second period.
3.SCACP> SHOW CHANNEL/1/3
The command in this example displays the first and third pages
of data for all channels. The first page contains Channel
Summary data, and the third page contains Channel Equivalent
Channel Set (ECS) data.
4.SCACP> SHOW CHANNEL/ALL
The following is a snapshot of the output for SHOW CHANNEL/ALL
command.
Channel Error Data describes the channel error data.
Table 1 Channel Error Data
Data Description
Seq Number of times a sequenced VC packet sent on
Retransmit this channel was retransmitted, and the channel
was penalized for the lost packet.
Note that the sequential retransmit is not
necessarily a reflection of lost packet. It
is possible that there can be a PE which could
have triggered a retransmitted and results in a
duplicate packet to be sent. This is reflected
in the number of duplicate packets received in
the remote node. The XMIT:REXMT ratio is also
a measure of for how many transmitted packet,
a packet was retransmitted. A very low value
(less than 1000) reflects a possible network
congestion.
LAN Transmit Number of times the local LAN device reported
Failures a failure to transmit a packet, and channel was
penalized for the lost packet.
Restart Close or restart because channel control packet
Channel received indicating that the other end closed
the channel and is restarting the channel
handshake.
Channel Init Channel initialization handshake timeout.
Timeouts
Listen No packets of any kind, including HELLOs, were
Timeouts received in LISTEN_TIMEOUT seconds.
Bad Received a Channel Control (CC) packet with a
Authorization bad authorization field.
Msg
Bad ECO CC Received a CC packet with an incompatible NISCA
Msg protocol ECO rev. field value.
Bad Received a bad multicast CC packet.
Multicast
Msg
CC Short Received a CC packet that was short.
Packet
CC Received a CC packet that was incompatible with
Incompatible existing channels for this virtual circuit.
Rcv Old Received a packet from an old instance of a
Channel channel.
No MSCP No MSCP server available to respond to a
Server received channel control solicit service packet
asking this node to boot serve another node.
Disk Not Disk is not served by this system.
Served
Buffer Size Change in buffer size.
Change
5.SCACP> SHOW CHANNEL/ECS
The following is a snapshot of the output for SHOW CHANNEL/ECS
command.
ECS State Channel ECS Membership Information
OpenVMS uses multiple interfaces to communicate with any other
node in order to do load balancing of communication. However,
at a given time not all interfaces that link the remote node
are used to transmit datagrams. OpenVMS maintains a set of
equivalent channels ECS (Equivalent Channel Set) within a VC.
These channels have approximately equivalent transmission
quality at a given time. Only the channels within the ECS
are used to transmit datagrams to the given node. "A" is the
generic format above may be "Y" (Yes) or "N" (No) stating
whether the channel is in the ECS or not. The remaining
characters specify the quality of the channel as they are
derived from the channel performance data. The characters are:
o A: T or L for Tight or Lossy
o B: P, S, I, U for Peer, Superior, Inferior or Ungraded
o C: F or S for Fast or Slow
For more details about ECS, see the section NISCA Transport
Protocol Channel Selection and Congestion Control in the HP
OpenVMS Cluster Systems manual.
NOTE
From OpenVMS Version 8.3 onwards, Topology change column
from SHOW CHANNEL/FULL or /5 has been removed. This is
because you must not consider this as an 'error' instead
it is the count of failovers from one interconnect to the
other interconnect. Whenever failover occurs to another
interconnect the buffer size changes. Hence this topology
change is counted under "Buffer SizeDecr" column in SHOW
VC/FULL output.
You can view the IP channel data summary by using the
/IPCHANNEL qualifier, for example:
$ SHOW CHANNEL <nodename>/IPCHANNEL
You can view the LAN channel data summary by using the
/LANCHANNEL qualifier, for example:
$ SHOW CHANNEL/LANCHANNEL