duplex modes

**4ndy** · 03-19-02, 05:10 PM

Hi,

I'm reading some threads on the board and it's recommended that the duplex mode should be set to 10 half mode?

Is this true even for 100mb NICs? If so how come? Surely 100 half mode would be better?

**Lobo** · 03-19-02, 05:12 PM

Are you on cable, profile does not say

**Lobo** · 03-19-02, 05:23 PM

If you are then please click on Cable Modem Tips in sig, or call ISP and see what they support, 10BaseT:

FOR CABLE MODEMS

It has been verified by experiment that certain auto-negotiating ethernet cards (both in PCs and in Macs), when connected to certain models of cable modem, sense the ethernet duplex setting incorrectly. Such a cable modem has ethernet hardware which is capable of operating only in half-duplex mode, at 10 Mbps, yet some auto-negotiating ethernet cards sense it as full-duplex. If an auto-negotiation card incorrectly starts operating in full-duplex mode, there can be collisions between ethernet packets being transmitted in both directions at the same time, leading to packet loss, and repeated re-transmissions. There is no visible evidence of this apart from poor performance. This problem can be avoided by manually configuring your ethernet card to be 10 Mbps half-duplex. No ill-effects will transpire from doing this, even when it is not necessary. The exact wording of the setting changes required varies from one manufacturer to another, so the instructions below are necessarily rather broadly defined.

To make this change under Win98/ME, follow these steps:

Open Control Panel.
Double-click Network.
From the scrollable list, select your Ethernet adapter (rather than any dial-up) with a green icon.
Click the button Properties.
Click the tab Advanced to bring it to the front:
In the Property box, the property name to be selected varies according to model of ethernet card. Examples are: Network Link Selection, Media Type, Connection Type, Duplex Mode, or any similarly-named property which can have Values looking like Auto-Negotiation, or 10BT, or 10BaseT.
In the Value box, select a value which either (a) explicitly says half-duplex or semi-duplex, or (b) at least does not say full-duplex [e.g. 10BaseT on its own is OK]. If there is a choice between 10 and 100 with half-duplex, choose the 10. Do not choose 10Base5, 10Base2, or AUI.
Click OK to exit the Adapter settings.
Click OK all the way out - you might need to restart.
To make this change under Windows 2000 or XP, follow these steps:

Open Control Panel.
Double-click Network and Dial-up Connections.
Identify the icon for your cable modem connection: usually Local Area Connection.
Right-click that icon and select Properties.
Under the ethernet adapter icon, click the button Configure.
Click the tab Advanced to bring it to the front:
In the Property box, the property name to be selected varies according to model of ethernet card. Examples are: Network Link Selection, Media Type, Connection Type, Duplex Mode, or any similarly-named property which can have Values looking like Auto-Negotiation, or 10BT, or 10BaseT.
In the Value box, select a value which either (a) explicitly says half-duplex or semi-duplex, or (b) at least does not say full-duplex [e.g. 10BaseT on its own is OK]. If there is a choice between 10 and 100 with half-duplex, choose the 10. Do not choose 10Base5, 10Base2, or AUI.
Click OK to exit the Adapter settings.
Click OK to exit the Connection properties

**ChuckDees** · 03-23-02, 03:22 AM

Would the same apply to a DSL user?

I currently have the MediaType set to 10 Half-Duplex in my NIC settings.

**Lobo** · 03-23-02, 07:59 AM

No I believe DSL modem are full duplex 10mbs, see DSL help guide in sig

**ChuckDees** · 03-23-02, 10:48 AM

Is it gonna mess with my speed connection if I choose the wrong mode?

**Lobo** · 03-23-02, 10:56 AM

Should be better if you choose right one

**ChuckDees** · 03-23-02, 11:08 AM

I'm pretty sure I'm on ADSL.

1288k down/325k up so what type of duplex mode do I need to use?

**Lobo** · 03-23-02, 03:05 PM

There is section on ADSL in DSL Guide below in signature:

Types of DSL
ADSL
The variation called ADSL (Asymmetric Digital Subscriber Line) is the form of DSL that will become most familiar to home and small business users. ADSL is called "asymmetric" because most of its two-way or duplex bandwidth is devoted to the downstream direction, sending data to the user. Only a small portion of bandwidth is available for upstream or user-interaction messages. However, most Internet and especially graphics- or multi-media intensive Web data need lots of downstream bandwidth, but user requests and responses are small and require little upstream bandwidth. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream. The high downstream bandwidth means that your telephone line will be able to bring motion video, audio, and 3-D images to your computer or hooked-in TV set. In addition, a small portion of the downstream bandwidth can be devoted to voice rather data, and you can hold phone conversations without requiring a separate line.