求解题库336 诊断duplex mismatch 题库答案和乾颐堂讲解不同

Shalltear

Which interface counter can you use to diagnose aduplex mismatch problem?

A. no earner

B. latecollisions

C. giants

D. CRC errors

E. deferred

F. runts

题库答案是late collision  乾颐堂讲解答案选  CRC errors

CRC Description:Cisco IOS sh interfaces counter. This increments when the CRC generated by theoriginating LAN station or far-end device does not match the checksumcalculated from the data received. Common Causes: This usually indicates noiseor transmission problems on the LAN interface or the LAN itself. A high numberof CRCs is usually the result of collisions but can also indicate a physicalissue (such as cabling, bad interface or NIC) or a duplex mismatch

Late-Col  Description: CatOS sh port and Cisco IOS shinterfaces and sh interfaces counters errors. The number of times a collisionis detected on a particular interface late in the transmission process. For a10 Mbit/s port this is later than 512 bit-times into the transmission of apacket. Five hundred and twelve bit-times corresponds to 51.2 microseconds on a10 Mbit/s system. Common Causes: This error can indicate a duplex mismatch among otherthings. Forthe duplex mismatch scenario, the late collision is seen on the half duplexside. As the half duplex side is transmitting, the full duplex side does notwait its turn and transmits simultaneously which causes a late collision. Latecollisions can also indicate an Ethernet cable or segment that is too long.Collisions must not be seen on interfaces configured as full duplex.

在官网上都有依据  求大神详解

wyang9311

两种可能性都有。

从字面上看，LATE COLLISION 似乎更接近些。因为一个端口的迟滞（LATE），会造成另一端口的MISMATCH。但是从发生错误的概率来说，CRC大约是百分之一点五，LATE COLLISION是百分之点零一。

所以我会选CRC。

参考资料见下：
1. http://noahdavids.org/self_published/duplex_mismatch.html
2. https://supportforums.cisco.com/ ... r-how-can-fix-these

ztbit

个人 认为：LATE COLLISIONS

Shalltear

wyang9311 发表于 2017-2-4 08:45
两种可能性都有。

从字面上看，LATE COLLISION 似乎更接近些。因为一个端口的迟滞（LATE），会造成另一 ...

确实实际操作基本出现的都是 CRC errors 而且题库里161题就是个例子