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| > | > | | > | > | says : "Supports full-duplex beginning with Cisco IOS Software | > Release | > | > | 12.0(4)T" | > | > | | > | > | But i can't configure full-duplex on this module, even with | > 12.1(2)T. | > | >
| > | > What do you mean by "can't"? Does the full-duplex configuration | > command | > | > in interface configuration mode give an error? | > | | > | I mean there`s no duplex configuration at all available for this | > | interface! (no "full-duplex", no "duplex full" or similar) | >
| > I have an NM-1E1R2W in a 3640 and it supports duplex configuration | > commands | > under IOS 12.4. I also have an NM-1E2W in another 3640 that I actually | > run | > in full-duplex mode without any obvious problems. (That is, I don't see | > any | > unexpected errors counted on it or on the full-duplex NM-2FE2W interface | > at | > the other end of the link.) Perhaps I'm deluding myself... | >
| > Dan Lanciani | > ddl@danlan.*com | | I'm sorry to say, that it doesn't work. I had issues with running | full-duplex on 10MB interfaces a number of years ago and after several weeks | of testing I found that it did not work. I did research on CCO and after | several hours of searching I found a document that explained that the 10MB | ethernet chipset that Cisco used on ALL of their 10MB interfaces (2500, | 2600, and NM moduels) do not support full-duplex operation.
I thought there was a change in chipset after the 2500 and original 4000 series interfaces. The revised 4000 series module (NP-2E-FDX) was 10Mb/s and supported full duplex.
| One of the side-effects of turning on full-duplex is that error counters are | no longer incremented when errors are detected on the interface,
This does not appear to be the case. I just looked at the above mentioned link between an NM-1E2W set to full duplex and an NM-2FE2W also set to full duplex. Counters were last cleared about six weeks ago; there were no unexpected errors. I then changed the setting on the NM-1E2W to half duplex (leaving the NM-2FE2W set to full duplex) and ran some cross-pings. Immediately I saw dropped packets and CRC errors were counted on the full duplex NM-2FE2W side as I would expect with a duplex mismatch. Restoring the NM-1E2W to full duplex stopped the errors and dropped packets. So something is going on.
Dan Lanciani ddl@danlan.*com