3Com 3C13612, Command Reference Manual

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Link Layer Protocol
X.25 defines two numbering modulus: 8 (also called the basic mode) and 128 (also
called extended mode), and the X.25 of the 3Com series routers supports both modes.
For related commands, see display interfaces , x25 call-facility , x25 map , x25 pvc ,
x25 switch pvc , x25 xot pvc , x25 fr pvc , x25 window-size .
Example
# Set the module on the X.25 interface Serial0 to 128.
[3Com-Serial0] x25 modulo 128
5.1.30 x25 packet-size
Syntax
x25 packet-size in-packets out-packets
undo x25 packet-size
View
Interface view
Parameter
in-packets : maximum transmit packet size in byte. It can be one of the following value:
16, 32, 64, 128, 256, 512, 1024. By default, the in-packets is 128.
out-packets : maximum receive packet size in byte. It can be one of the following value:
16, 32, 64, 128, 256, 512, 1024. By default, the out-packets is 128.
Description
Using the x25 packet-size command, you can configure the maximum incoming and
outgoing packet size for an X.25 interface. Using the undo x25 packet-size command,
you can restore to the default value.
Usually, the X.25 network has a maximum transmission packet size, and the size of a
packet sent by the DTE shall not exceed this length (otherwise it will trigger the
resetting of the virtual circuit). So, the DTEs at both the send and receive ends are
required to have the fragmentation and reassembling functions. The DTE at the send
end break the packet into more packets with the more data bit (M-bit) set except for the
last. When the DTE at the receive end receives this series of fragments, it reassembles
these fragments into a packet according to the M bit, and sends it to the upper-layer
protocol. Please consult your ISP about this maximum receive packet size.
Normally, the maximum receive packet size is equivalent to the maximum send packet.
Unless your ISP allows, please do not set these two parameters to different values.
For related commands, see x25 call-facility , . x25 pvc, x25 switch pvc, x25 xot pvc,
x25 fr pvc.
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