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New Member

Speed and Duplex on a fibre port

Hi All,

I have aquery with regards to speed and duplex setting on a fibre port. On my ASR1002 router when I connect a fibre sfp on a port it does not give me the option for setting the speed and duplex, however on the same port if i connect a copper sfp it allows me to configure speed and duples, can any one explain why? Below are the two modules connected.

NAME: "subslot 0/0 transceiver 0", DESCR: "GE SX"

PID: N/A                 , VID: A1C , SN: OPA10263660

NAME: "subslot 0/0 transceiver 2", DESCR: "GE T"

PID: N/A                 , VID: B2  , SN: AGM164222VQ

Thanks in advance

Regards

Umesh Shetty

3 ACCEPTED SOLUTIONS

Accepted Solutions

Speed and Duplex on a fibre port

Because the speed is set by the type of module it is (1000M) and the duplex is by the very nature of fibre, full duplex.  There's a separate physical strand for TX and RX so there's no situation where you'd ever want to or need to run half duplex.

Hall of Fame Super Gold

Speed and Duplex on a fibre port

I have aquery with regards to speed and duplex setting on a fibre port. On my ASR1002 router when I connect a fibre sfp on a port it does not give me the option for setting the speed and duplex,

Fibre optic only has one speed.  GLC-T, however, is multi-speed (depending on hardware).  Stick the same GLC-T on a 6500 and it becomes a 1Gbps-only.

Super Bronze

Re: Speed and Duplex on a fibre port

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Although the port you're using uses Ethernet, copper and fiber Ethernet are different standards.  As noted by another poster, fiber always has dedicated tx/rx so there's no reason for it not be full duplex whereas original Ethernet copper didn't support full duplex, full duplex later became an option with BaseT.

As to speed, in theory, fiber could support multiple speeds, but there wasn't much of a demand for it.  Also it would be much more complex to do so because of the different fiber specifications (e.g. SX vs. LX).

Original copper Ethernet and FastEthernet ports were single speed, but dual speed (and later triple speed) became an option to support different hosts speed capabilities.

6 REPLIES

Speed and Duplex on a fibre port

Because the speed is set by the type of module it is (1000M) and the duplex is by the very nature of fibre, full duplex.  There's a separate physical strand for TX and RX so there's no situation where you'd ever want to or need to run half duplex.

New Member

Speed and Duplex on a fibre port

What I can say is :

the GE fiber specification only makes provisions for the           negotiation of duplex, flow control, and remote fault detection. GE fiber ports           do not negotiate port speed.

--

Parvesh

Hall of Fame Super Gold

Speed and Duplex on a fibre port

I have aquery with regards to speed and duplex setting on a fibre port. On my ASR1002 router when I connect a fibre sfp on a port it does not give me the option for setting the speed and duplex,

Fibre optic only has one speed.  GLC-T, however, is multi-speed (depending on hardware).  Stick the same GLC-T on a 6500 and it becomes a 1Gbps-only.

New Member

Speed and Duplex on a fibre port

Hi Leo,

How do I identify what device will support spped negotiation and what device will not. Under the device specifications what should I actually look for to identify if the interface will support speed or duplex setting.

Thanks in Advance

Regards

Umesh Shetty

Hall of Fame Super Gold

Speed and Duplex on a fibre port

How do I identify what device will support spped negotiation and what device will not.

Just presume all SFP will be single-speed.

Super Bronze

Re: Speed and Duplex on a fibre port

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Although the port you're using uses Ethernet, copper and fiber Ethernet are different standards.  As noted by another poster, fiber always has dedicated tx/rx so there's no reason for it not be full duplex whereas original Ethernet copper didn't support full duplex, full duplex later became an option with BaseT.

As to speed, in theory, fiber could support multiple speeds, but there wasn't much of a demand for it.  Also it would be much more complex to do so because of the different fiber specifications (e.g. SX vs. LX).

Original copper Ethernet and FastEthernet ports were single speed, but dual speed (and later triple speed) became an option to support different hosts speed capabilities.

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