IEEE802.3ah%20EFM%20Task%20Force

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PHY OAM Baseline ProposalJune21-2002
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Introduction

• PHY OAM refinements based on feedback at Scotland
  meeting
• Especially addressing GE compatibility, and
  adding more technical details

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Scope of PHY OAM

• PHY OAM is applied for Full duplex fibers, P2P
  and P2MP
• PHY OAM is optional enhancements for EFM OAM
• PHY OAM is activated via MAC OAM Negotiation

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Functional PartitioningEthernet OAM Baseline in
May2002
Feature MAC OAM Data transported in frame PHY OAM State signaled in preamble
Event indication with diagnostics ?
Immediate non-intrusive signaling of PHY faults ?
MAC layer ping/loopback ?
Lower layer ping/loopback ?
Link monitoring ?
Different functions may be handled by different
transport. No functional overlap! PHY layer
defect indication and health check is important
for service providers
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EFM OAM Layers in 802.3
MAC OAM OAM Carrier Frame
MAC Client
MAC
RS
PHY OAM OAM Carrier Preamble
PH ( opt )
PCS
PMA
PMD
MDI
Medium
PH Preamble Handler function for PHY OAM (New
Clause)
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PHY OAM Function in PCS

• Preamble Handler ( PH, PHY OAM function ) inside
  PCS
• PCS State Machine, GMII MII, RS Unchanged
• PH has direct access to all PHY failure / status
  registers
• 1000BASE-X and G/MII Compatible
• PH now can synch with PCS tx_even alignment
  timing
• MDIO/MDC used as Management Interface
• Standard interface
• Only one new clause PH
• Include both interface specs for 1000BASE-X and
  100BASE-X

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PH location in PCS
GMII/MII
PH
Carrier Sense
TX
RX
PCS
Synch
AN
1) No change in PCS state machine. 2) PH has
direct access to all PCS registers
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1000BASE-X Compatibility
PH
(Logical PHY ID)
At PH
OAM
Rsvd
CRC8
Rsvd
Rsvd
tx_even
PCS TX RX
(Logical PHY ID)
Below PCS
OAM
Rsvd
CRC8
Rsvd
SPD
PCS
Rsvd

• PH has direct access to tx_even register in PCS.
• PH transmits Frame with PCS tx_even alignment
  timing.
• Preserves 8 byte preamble, while achieving no
  change on PCS state machine / GMII.
• At PCS TX IPG could vary between 11 to 13 bytes
  with average of 12 (Not an issue with Full Duplex
  Operation)

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PH Function (P2P)
RS
Pre- amble
Pre- amble
Pre- amble
Pre- amble
Pre- amble
Pre- amble
Pre- amble
At RS
SFD
GMII
PCS PH
Rsvd
At PH
Pre- amble
OAM
Rsvd
CRC8
Rsvd
Rsvd
Rsvd
PMA
Below PCS
OAM
Rsvd
CRC8
Rsvd
Rsvd
SPD
Rsvd
Rsvd

• TX PH replaces 2nd Preamble byte with PHY OAM,
  calculates CRC8 over 6-bytes of Preamble,
  replaces SFD with CRC8 value and passes it to
  PCS In the absence of Ethernet Frames, 8-byte
  OAM octets are sent.
• RX PH checks CRC8 on preamble, if correct, then
  process OAM byte, PH converts OAM Preamble to
  standard Preamble (7 bytes of 55 and 1 Byte SFD)
  and sends it to RS 8-byte OAM octets are
  terminated in PH.

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PH Function (P2MP)
RS
At RS
Logical PHY ID
Pre- amble
Pre- amble
Pre- amble
Pre- amble
Pre- amble
SFD
GMII
Logical PHY ID
PCS PH
Pre- amble
Rsvd
At PH
OAM
Rsvd
CRC8
Rsvd
PMA
Logical PHY ID
Below PCS
OAM
Rsvd
CRC8
Rsvd
SPD
Rsvd

• TX PH receives Preamble with Logical PHY ID
  from RS, PH replaces 2nd Preamble byte with PHY
  OAM, calculates CRC8 over 6-bytes of Preamble,
  replaces SFD with CRC8 value and passes it to
  PCS In the absence of Ethernet Frames, 8-byte
  OAM octets are sent.
• RX PH checks CRC8 on preamble, if correct,
  process OAM byte, replaces CRC8 byte with SFD and
  passes the Preamble to RS. If CRC8 is bad,
  disregard OAM byte and set RX_ER to indicate
  ERROR in Preamble 8-byte OAM octets are
  terminated in PH.

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How is PHY OAM Implemented?

• PH implements 20B FIFO Queue

• Normal Preamble/SFD substituted with OAM Preamble

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8
64
12
8
64
IPG
Pre/SFD
Frame
IPG
Pre/SFD
Frame
12
8
64
12
8
64
20-octet FIFO delay
IPG
Frame
IPG
Frame
PHY OAM
PHY OAM
IPG
Frame
IPG
Frame
OAM
PCS output
OAM
S
T
S

• PH may replace IPG octets with PHY OAM octets

• IPG (idles) substituted with PHY OAM octets

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12
IPG
IPG
IPG
8
12
12
20-octet FIFO delay
IPG
PHY OAM
IPG
IPG
IPG
IPG
IPG
PCS output
OAM
S
T

• PHY OAM octets ARE NOT FRAMES, do NOT PASS THE
  PH, and have NO IMPACT ON MAC FUNCTION
• S and T are PCS SPD and EPD

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PHY OAM Byte Bit definitions
8 bit OAM
0 Normal Operation
1 Local Fault

Type
Fault

Loopback
Alarm
00 OAM Preamble/ Normal Frame
01 Normal Preamble/Frame
10 OAM Preamble Only
11 Reserved
00 No Operation
01 PHY Ping Request
10 PHY Ping Response
11 PHY Loopback Active
00 Normal Operation
01 Signal Degrade
10 Signal Fail
11 Reserved
0 Normal Operation
1 Remote Fault
Signal fail Loss of Signal from RX Optical
module / Loss of Synch Signal degrade RX-CRC8
error counter threshold exceeded
PHY-Loopback only for P2P
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PHY Ping
Local
Remote
Ping Request ( 01 )
00 No Operation
01 PHY Ping Request
10 PHY Ping Response
Ping Response ( 10 )

• PING provides PHY Layer Availability Check
• Local sends Ping-Request and wait for Response.
• Remote sends Ping-Response upon Request
• Local can re-send Ping-Request after time out,
  or after receiving a response
• Provides Link test when upper layers may have
  failed.

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Link Fault Operation

• Link Faults include Local Fault (LF) Remote
  Fault (RF)
• When PHY- Rx path failure detected and when
  Local Fault is received, PH sends Remote Fault
  Signal to remote DTE indicate the transmit link
  of remote DTE is faulty
• Alarms (Signal Fail / Signal Degrade ) provides
  reasons of Rx-Failure
• PH qualifies received Fault Messages via a state
  machine

RS
RS
LF
PH ( opt )
PH ( opt )
PCS
PCS
PMA
PMA
PMD
PMD
RF
RX failure
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Link Fault Signaling Receive
Same functionality as 10GBASE-X Link Fault State
Machine As in Clause 46 Figure 46-9
No Fault
INIT
New Fault Detected
COUNT
Fault Count Met
UCT
New Fault Detected
FAULT
NEW_FAULT_TYPE
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Link Fault Signaling Transmit
INIT (Set TX_RF 0)
RX_LF 1 IN_FAULT_STATE
!IN_FAULT_STATE
SEND_RF (Set TX_RF 1)
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PHY OAM improvements over MAC OAM

• No BW impact on Data traffic
• Important for EPON where 32 ONUs are under OLT
• Important for bit level defect indications
• Need Physical layer health check / failure
  isolation
• Isolation of Link failure from failures above
  PHY
• Current Auto-negotiation in GE does not provide
  RF while link is broken
• LF/RF combined with Logical PHY ID CRC8
• Provide faster detection indication than MAC
  OAM
• Non PHY based OAM needs management entities
  involvement for PHY Failure Detection /
  Indication
• Link speed Physical layer failure detection,
  diagnostics and response

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Backup
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PH Location Evolution
RS Mar2002 Between RS PCS May2002 PCS July2002
Control interface for Msg byte Use Pervasive access to RS N/A N/A
PHY layer Fault signaling to PH New fault signals across GMII New fault signals across GMII No change to GMII
GE compatibility Require change in GMII or PCS Require change in GMII or PCS No change to GMII / PCS state machine