One other thing to look at is if the media converter uses store and forward. I ran into an issue a few years ago with the AP300 connected to a mediaa converter where packets were being randomly dropped across the link. We were able to use the dip switches on the converter to configure it to not store and forward the frames and this resolved the issue.

Thank you for quick and good insight, Marcus san Yes, our customer is using ether link with auto and fixed, a little inconsistent. So we will configure correct mode at each ends of etherlink.

And we're exploring for 1000M media converter supporting auto, because AP650(wing4) supports only auto negotiation, However, couldn't reach one available.

Thank you Randt san, these are good reference products. SPOEB is available in my country, we will use this for 100Mbps solution.

Does anybody have any experiences using 1000M media converter?

Keep in mind... 1) Auto negotiate is only supported on wired connections...not Fiber. 2) When a media converter supports auto, they are refering to the wired side only 3) 802.3u defines autonegotiation, but there are many proprietary implementations and the 802.3u standard was written befor gig ethernet. Depending on the 2 piectes of equipment it may be a proprietary method which is not compatibe with the equipment on the other end 4) The 802.3u standard does not specify a "default" fail mode. As a result, if autonegotiate fails, one end may fail to 1/2 duplex and the other end to full duplex. 5) Be careful of distances on multi mode fiber with gigabit transcievers. I have forgotten the approved distances, but they are significantly less than 100base FX and there are a few different types of optics used on gig transciver links the heavier the traffic, the worse the CRC error and packet loss becomes.. If in doubt..set the links A very reliable way to test if a link is dropping packes is to use the extended ping utility on a cisco router. This permits  configuration of packet size and number of pings which results in very agressive network utilization in both directions. Typically if you confgure 1024 packet size and 1000 pings you will see a problem if one exists. If there is a mismatch, it will pause and drop packets during this test...On a LAN connection, if  more than 1 packet drops, it is likely that there is a problem with either the duplex or the hardware is faulty . I have never seen a duplex mismatch which did not reveal itself under these tsting conditions. 

The most common cause of dropped packets in an ethernet environment with media converters is duplex mismatch. This is because the "autonegotiate"  functionality does not work in mixed media environments and when the mechanism fails, the components (switch or AP) fail to a pre determined speed and duplex. I would suggest hard setting the duplex on the switch and the AP to Full duplex and testing

We have a customer who is using AP650s connected to an RFS6000.  They are using a media converter from Transition Networks, it is a 10/100Base-TX to 100Base-FX power over ethernet converter, model SPOEB.  They have not had any issues at all and have thousands deployed.  They run fiber from the MDF, along with a 12/2 power wire to the media converter for its power, then connect a Cat5E from the media converter to the AP650 which also supplies POE to the AP650.  The media converter also comes with its own power supply so you can plug it into a local outlet if required. In the MDF, they decided to go with a rack mounted media blade, using a CBFTF1013-105 media blade converter in each blade, but you can use the SPOEB at each end if you prefer