Lapb Max-Frame - H3C MSR 20-20 Command Reference Manual

lapb max-frame

Syntax
View
Parameter
Description
Example
tcp peer ip: 10.1.1.1, peer port: 1998
tcp local ip: 10.1.1.2, local port: 1024
socket keepalive period: 5, keepalive tries: 3
come interface name: Serial1/0-10.1.1.1-1024
go interface name: Serial1/0
lapb max-frame n1-value
undo lapb max-frame
Interface view
n1-value: N1 value of the LAPB parameter in bits, in the range 1096 to 12104. It is
the maximum value of a frame expected from the DTE or DCE, 8 times the value
of MTU plus the protocol header.
Use the
lapb max-frame
Use the
undo lapb max-frame
The default value of N1 is calculated according to the MTU, upper layer protocol
and modulo, as shows below:
Table 64 Difference between N1 and MTU (in bytes) versus upper layer protocol and
modulo
Upper layer protocol
IP/IPX
IP/IPX
Multiprotocol
Multiprotocol
X.25
X.25
The default value of N1 varies with MTU and modulo.
For example, upon system initialization, the upper layer protocol is IP, modulo 8
and MTU 1500, so the default value of N1 is (1500+4)*8 = 12032. If the modulo
is set to 128, then the default value of N1 is (1500+5)*8 = 12040. You can use the
undo lapb max-frame command to restore the new default. For the same
reason, N1 changes with the change of MTU.
# Set the LAPB N1 parameter to 1160 on Serial 2/0.
<Sysname> system-view
[Sysname] interface serial 2/0
[Sysname-Serial2/0] lapb max-frame 1160
command to configure the LAPB N1 parameter.
command to restore the default.
Modulo
8
128
8
128
8
128
433
Difference between N1 and
MTU (bytes)
4
5
6
7
7
8