3Com 3031 Command Reference Manual page 341

[3Com] interface virtual-template 10
[3Com-Virtual-Template10] ip address 202.38.160.1 255.255.255.0
[3Com-Virtual-Template10] quit
And then PVC 1/101 at ATM interface Atm1/0/0 is created.
[3Com] interface atm 1/0/0
[3Com-Atm1/0/0] pvc 1/101
The newly created VT interface is used to create the PPPoA mapping.
[3Com-atm-pvc-Atm1/0/0-1/101] map ppp virtual-template 10
mtu
Syntax
mtu mtu-number
undo mtu
View
Interface view
Parameter
mtu-number: MTU size of ATM interface in bytes, the range of the value is 128 to
16384.
Description
Using the mtu command, you can set the size of Maximum Transmission Unit
(MTU) of the ATM interface. Using the undo mtu command, you can restore the
default of the value.
By default, 1500 bytes.
MTU of ATM interface only influences the packet assembling and packet
disassembling of IP layer at the ATM interface. Because of the limit of the QoS
queue length (for example, the default length of the FIFO queue is 75), the too
small MTU will lead to too many fragments and will be dropped by the QoS
queue. In this case, the length of the QoS queue can be enlarged appropriately.
FIFO is the queue dispatching mechanism used by PVC by default, and its queue
length can be changed by using the fifo queue-length command in the PVC view.
This command can be used in ATM main interface and sub-interface at the same time.
Example
Display how to set MTU of ATM interface Atm1/0/0 to 1492 bytes.
[3Com-Atm1/0/0] mtu 1492
oam frequency
Syntax
oam frequency frequency [ up up-count down down-count retry-frequency
retry-frequency ]
ATM Configuration Commands 341