Verilink 9000 Series (34-00271) Product Manual - Manual (Page 267)

Configuration / Operation 245
Packet Size
The Packet size field indicates the number of data bytes allowed in a packet. The
value of this field has no bearing on the size of messages that can be sent or
received by end users.
The packet size should be smaller than the configured MTU (maximum transfer
unit) in the IP layer configuration to avoid fragmentation at the IP layer.
Fragmentation and reassembly of IP datagrams is a time- and memory-consuming
process and is best avoided with the exception of a few applications where the IP
backbone tends to resequence the received datagrams. In this case, the PLP layer
detects sequencing errors and resets the logical channel causing retransmission. To
avoid that, set the packet size to one message and left the IP layer segments the
message. In this case, the message reassembles in the previous IP layer to be
passed to the PLP layer, avoiding the sequence errors at the PLP layer.
The selections are 64, 128, 256, 512, 1024, variable, variable up to 1.8 kilobytes,
and 1 message.
Call Request Timer
After the MultiPro unit sends a Call packet to the remote unit, it waits up to the
Call Request Timer value before a Clear packet is sent. The selections are 1 to 255,
15.
Clear Request Timer
After the MultiPro unit sends a Clear packet to the remote unit, it waits up to the
Clear Request Timer value before declaring a channel failure. The selections are 1
to 255, 15.
Data ACK Timeout
The Data ACK Timer indicates the delay a transmitting channel waits to receive an
acknowledgment to a message transmitted. This timer is needed because an IP
network can drop packets without notification. This timer prevents a deadlock
situation in case the last packet of a message has been dropped. If the timer
expired, the channel is reset and the message is retransmitted. The selections are 0
to 512, 60.
Window
The VC Window parameter indicates the maximum number of unacknowledged
packets that may exist at one time on a virtual circuit. This number must be
between one and one less than the Modulo 128 field described on page 246. The
selections are decimal 1 to 7, 7 if Modulo 8 and 1 to 127 if Modulo 128, 7.