Cisco - Định nhĩa MTU

Cisco ATM router interfaces support an MTU between 64 and 17966 bytes. Eachinterface supports a default maximum packet size. For example, the maximum value is9288 bytes on both the ATM interface processor (AIP) and network processor module(NP), and 4470 bytes on the PA-A3 and PA-A2 port adapters.
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Cisco - Định nhĩa MTUMaximum transmission unit (MTU) defines the largest size of packets that an interfacecan transmit without the need to fragment. IP packets larger than the MTU must gothrough IP fragmentation procedures.Cisco ATM router interfaces support an MTU between 64 and 17966 bytes. Eachinterface supports a default maximum packet size. For example, the maximum value is9288 bytes on both the ATM interface processor (AIP) and network processor module(NP), and 4470 bytes on the PA-A3 and PA-A2 port adapters.This document reviews the default MTU values for ATM interfaces and clarifies when arouter increments the AAL5 Oversized SDUs and the AAL5 length violation counters.Why are MTUs 4470 Bytes?Most Cisco ATM router interfaces use a default MTU size of 4470 bytes. This numberwas chosen to match exactly Fiber Distributed Data Interface (FDDI) and High-SpeedSerial Interface (HSSI) interfaces for autonomous switching.Use the mtu command in interface configuration mode to configure a non-default value.Note that subinterfaces support a value that is different from the main interface as long asthe main interfaces value is as large as, or larger than the largest subinterface MTU.[miễn là giá trị MTU của cạc chính lớn hơn (as large as) hoặc lớn hơn giá trị lớn nhấtcủa SUBINTERFACE MTU]subMTU là giá trị các cổng khác 1500