OpenVMS Cluster Systems - OpenVMS Systems - HP

Table F–10 Fields in the CC Header
Field Description
Troubleshooting the NISCA Protocol
F.7 Understanding NISCA Datagrams
Datagram type (bits ) Identifies the type of message on the Channel Control level. The following table
shows the datagrams and their functions.
Value
Abbreviated
Datagram
Type
0 HELLO HELLO
datagram
message
1 BYE Node-stop
notification
Expanded
Datagram
Type Function
Multicast datagram that initiates
the formation of a channel between
cluster nodes and tests and
maintains the existing channels.
This datagram does not contain a
valid cluster password.
Datagram that signals the
departure of a cluster node.
2 CCSTART Channel start Datagram that starts the channelformation
handshake between
two cluster nodes. This datagram
is sent in response to receiving
a HELLO datagram from an
unknown LAN adapter address.
3 VERF Verify Datagram that acknowledges the
CCSTART datagram and continues
the channel formation handshake.
The datagram is sent in response to
receiving a CCSTART or SOLICIT_
SRV datagram.
4 VACK Verify
acknowledge
5 Reserved
6 SOLICIT_
SERVICE
7–15 Reserved
Datagram that completes the
channel-formation handshake. The
datagram is sent in response to
receiving a VERF datagram.
Solicit Datagram sent by a booting node
to form a channel to its disk server.
The server responds by sending a
VERF, which forms the channel.
Datagram flags (bits ) Provide additional information about the control datagram. The following bits are
defined:
• Bit (AUTHORIZE)—Set to 1 if the cluster password field is valid.
• Bit (Reserved)—Set to 1.
• Bit (Reserved)—Set to 0.
Cluster password Contains the cluster password.
• Bit (TR/CC flag)—Set to 1 to indicate the CC datagram.
F.7.7 Transport (TR) Header
The transport (TR) header is used to pass SCS datagrams and sequenced
messages between cluster nodes. The important fields for network
troubleshooting are the TR datagram flags, message acknowledgment, and
sequence numbers. Note that because the CC and TR headers occupy the same
Troubleshooting the NISCA Protocol F–23