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Remote Fault & Break Link Proposal
for 10-Gigabit Ethernet
Howard Frazier
Cisco Systems Inc.
Shimon Muller
Sun Microsystems Inc.
New Orleans; September 12, 2000
1
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Outline
s Introduction
s Concept
s State Machines
s What About OAM&P?
s Summary
2
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Introduction
s This proposal provides a robust mechanism for supporting two
(and exactly two) primitives
s Remote Fault
s Indicates that a problem has been detected by the remote receiver
s The source of the fault could be at:
s Local transmitter
s Interconnecting channel
s Remote receiver
s Break Link
s Intended to reset the channel and re-start the synchronization process
s Both primitives indicate the occurrence of serious problems
s Totally preclude data exchange
3
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Concept
s Break Link
s Low-level continuous signaling
s K28.7 across all four lanes on XAUI
s No alignment required
s Mapped to a “reserved0” 64b/66b Control Frame for UniPHY
s Sent for the duration of ~10msec
s During start up
s When one end of the link loses synchronization
s Effect of receipt
s Set the link status bit to “down”
s Reset the link synchronization state machine and the de-skew logic
4
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Concept (continued)
s Remote Fault
s Low-level continuous signaling
s K28.1 interleaved with normal (randomized) Idle across all four lanes on XAUI
s No alignment required
s K28.1 is mapped to a “reserved1” 64b/66b Control Frame for UniPHY
s Sent forever
s Whenever the local receiver cannot achieve synchronization
s Effect of receipt:
s Keep the link status bit as “down”
s Set the Remote Fault status bit when local receiver is in synch and it continues
receiving RF signals
s Once set, the Remote Fault status bit is only cleared when link status is “up”
5
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Transmit Synchronization State Machine
Reset
START BL_rcvd + !rx_in_sync
Send BL UCT
Enable 10ms_timer
Clear link_up_status 10ms_timer_done * (BL_rcvd + !rx_in_sync) * !RF_rcvd
10ms_timer_done * (BL_rcvd + !rx_in_sync)
10ms_timer_done
NO_SYNC_2 NO_SYNC_1
!rx_in_sync
Send 16 columns of Idle Send 16 columns of RF
!rx_in_sync
rx_in_sync
IN_SYNC_1
rx_in_sync
Send Idle
Enable 10ms_timer
Clear RF_rcvd
10ms_timer_done * !BL_rcvd * rx_in_sync
IN_SYNC_2
10ms_timer_done * RF_rcvd
Send Idle
Enable 10ms_timer
FAULT
10ms_timer_done * !BL_rcvd * rx_in_sync * !RF_rcvd
Set RF_status
UP
Set link_up_status
Clear RF_status
6
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Receive Detection State Machines
Reset Reset Reset
CLEAR CLEAR CLEAR
5ms_timer_done *
!rx_sync_detected Clear rx_in_sync !BL_detected Clear BL_rcvd clear RF_rcvd Clear RF_rcvd
rx_sync_detected clear RF_rcvd RF_detected
!BL_detected BL_detected
SET WAIT WAIT
Set rx_in_sync BL_count = BL_count + 1 RF_count = RF_count + 1
Clear 5ms_timer
rx_sync_detected !rx_sync_detected (BL_count = 255) * BL_detected (RF_count = 255) * RF_detected
WAIT SET SET
Enable 5ms_timer Set BL_rcvd Set RF_rcvd
RX Synch Detection S.M. RX Break Link Detection S.M. RX Remote Fault Detection S.M.
Notes:
* rx_sync_detected = signal_detect * pll_lock * lane0_in_sync * lane1_in_sync * lane2_in_sync * lane3_in_sync
* BL_detected = (lane0 = K28.7) * (lane1 = K28.7) * (lane2 = K28.7) * (lane3 = K28.7)
* RF_detected = (lane0 = K28.1) * (lane1 = K28.1) * (lane2 = K28.1) * (lane3 = K28.1)
7
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
What About OAM&P?
s There seems to be a wide consensus that OAM&P support in the
WAN should be a mandatory function for 10 Gigabit Ethernet
s To date, it does not appear that the same level of consensus ex-
ists regarding the necessity of this function in LAN applications
s If 802.3ae decides to provide support for OAM&P in the LAN, such
a solution should architecturally easily scale to higher speeds
s LSS, as proposed, does not meet this requirement
s Relies on the existence and a minimum duration of the IPG
s What about 100 Gigabit Ethernet that uses 8-wavelength WDM?
s Potential solutions:
s Use the WAN PHY in LAN applications
s Frame-based approach
s Very low overhead --- OAM&P information requires very little bandwidth
s Can use high level management frames (SNMP)
s Alternatively, a low level MAC frame can be defined (similar to 802.3x)
8
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
Summary
s The proposed solution for Link Break and Remote Fault functions
accomplishes the desired goals using a mechanism which is:
s Robust
s Continuous signaling
s No alignment required
s Predictable behavior
s Simple and cheap
s One state machine
s Two timers
s Two counters
s Scalable
s Does not rely neither on the existence nor the duration of an IPG
s Will work for all speeds (100-Gigabit Ethernet,....)
s Support for OAM&P in the LAN is unrelated to LB/RF and should
be considered on its own merits
s We recommend that this proposal be adopted by 802.3ae as basis
for further work for the 10-Gigabit Ethernet standard
9
IEEE 802.3ae
10 Gigabit Ethernet S. Muller - Sun
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