Global Foundation Services

Brad BoothPrincipal Network Engineer, Global Networking Services1TPCE Study GroupNorfolk, VA

Auto-Negotiation Overview

Supporters

What is Auto-Negotiation (AN)?• Method to exchange information between 2

stations• Used to configure operating parameters• Permits automatic link establishment without

management intervention• Uses lane 0 even with multi-lane protocols

802.3 Auto-Negotiation• More than one auto-negotiation protocol

• Clause 28 – Has been the primary twisted-pair protocol for eons

• Clause 37 – Was used for 1000BASE-X… and never again

• Clause 73 – Used for backplane and copper cable assembly (e.g. twinax)

• Establish the operating parameters before bringing up the link• Clause 28 uses fast link pulses (FLP)

• Clause 73 uses differential Manchester encoding (DME)

• Clause 37 determines operating parameters after the link is up

5

Base Pages• Establishes the primary operating

parameters of the link• Duplex

• Rate

• Coding/FEC

• Issues the call for next pages (NP) or extended next pages (XNP) if required• 1000BASE-T and 10GBASE-T require NP or XNP

Ethernet Technology Summit - April 2014

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Next Pages• Next pages and extended next pages are

exchanged one at a time• Pages are exchanged until both stations have

exhausted their next pages

• May communicate other relevant operating parameters• Master/slave

• Pause

• Vendor-specific information• Message format specified

• Information exchanged is up to the implementer

Ethernet Technology Summit - April 2014

Negotiating Auto-Negotiation• 802.3 has more than one auto-negotiation

protocol• Use one as is, edit existing one or create new?

• Edit is recommended… Clause 28? New clause?

• What is 802.3bp doing?• Is plug’n’play interoperability needed?

• Is rate negotiation required? Ability to bypass rate negotiation?

• Anything else that may require negotiation?

• Mandatory or optional?• Can be rate dependent

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Thoughts…• Decide on adding AN objective to 802.3bp

and the 1TPCE study group• Each effort may decide whether AN is

optional or mandatory

• Once decision is to do AN for both, future discussions on:• New, re-use, etc.

• Base pages, next pages

• Bypass, etc.

Ethernet Technology Summit - April 2014

Global Foundation Services

Thank You!