I put both groups on this just in case someone is not on both reflectors.
There are a few aspects to FEC and Autoneg that the TF and SG may wish to consider:
- Exchanging FEC abilities
- Agreeing upon FEC use
- Switching between FEC on/off
- Autoneg location
Autoneg location has been an interesting discussion in the past (P802.3ap for instance). The optical domain autoneg in Gigabit Ethernet was performed in Clause 37 which had the autoneg function as part of the PCS. The electrical domain autonegs have been
performed at the bottom of the stack between the MDI and the PMD (Clause 28 and 73). Adding an optical domain autoneg to be similar to that used by the electrical domain may not be worth the effort considering there are other alternatives.
Also, autoneg works fine for #1 and #2, but doesn’t work well in situation #3. For example, upon link bring-up if the local device and link partner have exchanged that they are both capable of FEC but have decided not to use it, the only way for FEC to
be turned on at a later point in time is to perform another autoneg. Whether in the electrical or the optical domain, restarting autoneg to switch FEC on and off is very cumbersome due to traffic interruption and link downtime.
A possible solution to solve #3 and #4 is the following:
- Electrical domain autoneg (for .3bj) uses Clause 73 for #1 and #2
- Optical domain uses PCS level sequence order sets to perform #1 and #2
- Both electrical and optical use sequence order sets for #3
There are likely corner cases that would need to be considered in an implementation, but the goal should be to provide a mechanism by which a system can perform these operations in a manner to eliminate the corner cases.
Thoughts?
Cheers,
Brad
From: Oren Sela [mailto:orens@xxxxxxxxxxxx]
Sent: Wednesday, November 30, 2011 11:16 AM
To: STDS-802-3-100GCU@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GCU] 802.3bj Auto-negotiation consensus building
One more thing to consider-
This is not necessarily a 802.3bj issue but we need to think about it – there was some discussion in the next generation optics study group about FEC. If we’ll end up with optional FEC for the optical
interface we will probably want to use the same CL73 AN for negotiating the FEC. It makes sense to do this once and add the 100GBASE-SR4 for example to the CL73 base page.
If we decide to take this path we need to make sure that the slow frequency of the DME pages (312.5 MHz) is physically feasible on a 25 Gb/s optical interface.
Thanks,
Orens
From: Chalupsky, David [mailto:david.chalupsky@xxxxxxxxx]
Sent: Wednesday, November 30, 2011 6:52 PM
To: STDS-802-3-100GCU@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GCU] 802.3bj Auto-negotiation consensus building
Thanks for the proposal, Arthur.
This is a great start. There are a couple dependencies upon baselines in other areas that could affect this.
- FEC - if we have an optional FEC how does that affect AN?
- Multi signaling schemes: if a PAM4 baseline is adopted in addition to NRZ we will need more fields and naming to distinguish them. We would also need to discuss the priority. Process-wise, should we leave it to PAM-4 supported
to propose the AN solution as part of their baseline?
Thanks,
Dave
-
Folks,
Below follows a draft baseline proposal for 802.3bj auto-negotiation. Please let me know if:
- You wish to be listed as a supporter
- You wish to be involved in consensus building discussions
- You have any comments on the proposal
Arthur Marris (arthurm at cadence dot com)
802.3bj Baseline Proposal for Auto-Negotiation
Assumptions:
- Implementation of Auto-Negotiation will be mandatory for 100GBASE-KR4 and 100GBASE-CR4
- 802.3bj EEE (Energy Efficient Ethernet) will make use of AN next pages just like 802.3az
- 802.3bj will take the same approach as 802.3ba for Auto-Negotiation
Proposed revisions to IEEE 802.3-2012:
Clause 30:
Change 30.6.1.1.5 aAutoNegLocalTechnologyAbility attribute to insert 100GBASE-KR4 and 100GBASE-CR4 after 100GBASE-CR10.
Clause 45:
Change 45.2.7.12 Backplane Ethernet, BASE-R copper status (Register 7.48) register to include 100GBASE-KR4 and 100GBASE-CR4. Insert 100GBASE-KR4 and 100GBASE-CR4 bits into Table 45–172 and 45.2.7.12.2 Negotiated Port Type.
Change 45.2.7.13 EEE advertisement (Register 7.60) to include 100GBASE-KR4 and 100GBASE-CR4. Insert 100GBASE-KR4 and 100GBASE-CR4 bits into Table 45–173 and Table 45–174. Insert subclauses for the bit definitions as necessary.
Clause 73:
Change note at beginning of Clause 73 to read “Note that although the Auto-Negotiation defined in this clause was originally intended for use with Backplane Ethernet PHYs, it is also specified for use with 40GBASE-CR4, 100GBASE-CR10
and 100GBASE-CR4 PHYs.”
Change last sentence in third paragraph of 73.3 to read “Technology-Dependent PHYs include 1000BASE-KX, 10GBASE-KX4, 10GBASE-KR, 40GBASE-KR4, 40GBASE-CR4, 100GBASE-CR10, 100GBASE-KR4 and 100GBASE-CR4.”
Change Table 73-4 Technology Ability Field encoding to insert A6 for 100GBASE-KR4 and A7 for 100GBASE-CR4.
Change third paragraph in 73.6.4 to read “40GBASE-CR4 and 40GBASE-KR4 shall not be advertised simultaneously and likewise 100GBASE-CR4 and 100GBASE-KR4 as their physical interfaces are different.
Change last sentence in 73.7 Receive function requirements to read “The receive function incorporates a receive switch to control connection to the 1000BASE-KX, 10GBASE-KX4, or 10GBASE-KR, 40GBASE-KR4, 40GBASE-CR4, 100GBASE-CR10,
100GBASE-KR4 or 100GBASE-CR4 PHYs.”
Change 73.7.1 DME page reception to read “To be able to detect the DME bits, the receiver should have the capability to receive DME signals sent with the electrical specifications of the PHY (1000BASE-KX, 10GBASE-KX4, 10GBASE-KR,
40GBASE-KR4, 40GBASE-CR4, 100GBASE-CR10, 100GBASE-KR4 or 100GBASE-CR4). The DME transmit signal level and receive sensitivity are specified in 73.5.1.1.”
Change last sentence of 73.7.2 Receive Switch function to read “During Auto-Negotiation, the Receive Switch function shall connect the DME page receiver controlled by the Receive state diagram to the MDI and the Receive Switch
function shall also connect the 1000BASE-KX, 10GBASE-KX4, 10GBASE-KR, 40GBASE-KR4, 40GBASE-CR4, 100GBASE-CR10, 100GBASE-KR4 and 100GBASE-CR4 PMA receivers to the MDI if the PMAs are present.”
Change Table 73–5—Priority Resolution to insert 100GBASE-CR4 at priority 1 and 100GBASE-KR4 at priority 2 and move the existing entries in the table down appropriately.
Insert appropriate variable for 100GBASE-KR4 and 100GBASE-CR4 into 73.10.1 State diagram variables
Clause 80:
Change the last sentence of 80.2.6 Auto-Negotiation to read “Clause 73 Auto-Negotiation is used by the 40 Gb/s and 100 Gb/s backplane PHYs (40GBASE-KR4 and 100GBASE-KR4) and the 40 Gb/s and 100 Gb/s copper PHYs (40GBASE-CR4,
100GBASE-CR10 and 100GBASE-CR4).”
Clause 82:
Change the first sentence of 82.6 Auto-Negotiation to read “The following requirements apply to a PCS used with a 40GBASE-KR4 PMD, 40GBASE-CR4 PMD, 100GBASE-CR10, 100GBASE-KR4 or 100GBASE-CR4 PMD where support for the Auto-Negotiation
process defined in Clause 73 is mandatory.”