full-duplex mode on NM-1E1R2W

Hello,

i want to use the above network module (one ethernet, one token ring) in a 3640 for a 10mbit leased line with full-duplex.

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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.

router#show int e4/0 Ethernet4/0 is up, line protocol is down Hardware is AmdP2, address is 0002.1649.d761 (bia 0002.1649.d761) MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, reliability 128/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) [...]

Does this module supports full-duplex mode? Any hints welcome..

Regards,

Karsten

Reply to
Karsten Fischer
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Full duplex is not supported on any 10Mb only ethernet interfaces on Cisco routers. The 10MB ethernet chipset that Cisco used did not support full duplex mode. On the 2600 series platform you could set full-duplex on the

10MB interfaces (with an error), but the interface still ran at half-duplex. CDP and show interface would report the interface was in full-duplex, but this was a bug and was really running in half-duplex mode. In order to run 10MB full-duplex you need a fast-ethernet interface.

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says : "Supports full-duplex beginning with Cisco IOS Software Release

Reply to
Thrill5

In article , snipped-for-privacy@nexgo.de (Karsten Fischer) writes: | Hello, | | i want to use the above network module (one ethernet, one token ring) in | a 3640 for a 10mbit leased line with full-duplex. | |

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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?

| router#show int e4/0 | Ethernet4/0 is up, line protocol is down | Hardware is AmdP2, address is 0002.1649.d761 (bia 0002.1649.d761) | MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, | reliability 128/255, txload 1/255, rxload 1/255 | Encapsulation ARPA, loopback not set | Keepalive set (10 sec) | [...]

I don't think you will see anything there. Try "show controller e4/0" and look after BCR9= around line 7.

Dan Lanciani ddl@danlan.*com

Reply to
Dan Lanciani

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I mean there`s no duplex configuration at all available for this interface! (no "full-duplex", no "duplex full" or similar)

Because of this, the leased line will be terminated on a switch, which is availabe at this location an routed on a subinterface from another fast-ethernetport.

Thanks, Karsten

Reply to
Karsten Fischer

Even if the command were there, the hardware DOES NOT SUPPORT full-duplex mode. If you need a 10MB full-duplex connection, you need an NM-1FE or similar.

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Reply to
Thrill5

In article , snipped-for-privacy@nexgo.de (Karsten Fischer) writes: | Dan Lanciani wrote: | > In article , snipped-for-privacy@nexgo.de (Karsten Fischer) writes: | > | Hello, | > | | > | i want to use the above network module (one ethernet, one token ring) in | > | a 3640 for a 10mbit leased line with full-duplex. | > | | > |

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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

Reply to
Dan Lanciani

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| > |

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. (In addition, only some them support 802.1q trunking). I opened a TAC case about this and it was confirmed that 10MB interfaces do not support full duplex as this is something that must be supported in hardware and is not something than can reprogrammed via software. I tried to get them to open a bug report that if the interface does not support full duplex then the full duplex command should NOT be available.

I just spent about an hour searching CCO again and unfortunately I could not find the document again. It's been so long ago that I don't remember what key words will bring up the document and I don't recall if it was in a release note, a technical note, or a bug report.

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, and CDP will report that the interface is full duplex. The reason that this problem is there is that the 100MB chipset that Cisco uses is backward compatible with the 10MB chipset, with the exception of full duplex operation. (A later version of the 10MB chipset supports 802.1q trunking while the previous version does not.) The underlying driver interface is the same for all three chipsets, and so you can issue the IOS commands but they have no effect on the hardware if they are supported and no error is generated. If you don't believe me, you can verify my results by connected two routers back-to-back and turn on full-duplex. The output packets on one side should match the input packets on the other side, but you will see that they don't. The higher the sustained througput rate, the bigger the number of packets will differ. If you attach a tap in between and attach a sniffer, you will see retransmissions that are not seen on either interface. You will also see that on the 10MB side you will not get more than about 3Mb/s of traffic, which is the practical limit of a half-duplex 10MB interface.

Reply to
Thrill5

The command might just be missing from the help?

You should just enter the corerct command and see if it accepts it.

I have no experience of thses cards but it is very rare to unheard of for cisco documentation to be wrong on such a simple and unambiguous matter. Sorry Mr. Thrill5:)

I would though expect the sh int to list the duplex setting:( Oh on my router here it is the line below the one last one posted.

FastEthernet0 is up, line protocol is down Hardware is Fast Ethernet, address is xxxxxx MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Auto-duplex, Auto-speed

I have noticed that the NM-1FE1R does support "full duplex token ring" and the NM-1E1R does not. Maybe that is the confusion?

Of course it should be [full duplex token-less ring-less token ring] since there are neither tokens nor rings but its long gone now so who cares:)

Reply to
bod43

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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

Reply to
Dan Lanciani

Here is the data sheet for the Ethernet chip used on the 10Mb/s NM- modules:

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Dan Lanciani ddl@danlan.*com

Reply to
Dan Lanciani

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