Fibre Channel Over MPLS

Fibre Channel Over MPLS

•IETF/T.11 interworking•draft-ietf-pwe3-fc-encap-02.txt•Tuesday, November 7th, 2006

•Moran Roth – Corrigent •Ronen Solomon – Corrigent •Munefumi Tsurusawa – KDDI LABs

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Topics

New draft draft-ietf-pwe3-fc-encap-02.txt

• Reliable congestion control

• Encapsulation format

• Signaling of FC PW

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FC PW congestion control - Rate control

Based on TFRC (RFC 3448)

CIR and EIR are configured per FC service and

FCoMPLS frames are marked accordingly.

Throughout [Bytes/Sec] – actual sending rate is a

function of loss event rate and round trip time (RTT).

Loss event – one or more frames dropped within a

single LAPB window

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FC PW congestion control - Selective

retransmission

Based on LAPB (FC-BB-3 standard)

Reliable protocol

• Sequencing and re-sequencing mechanism

• Acknowledgments - to the sender

Frame loss retransmission

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FC PW congestion control - Selective

retransmission (cont.)

LAPB message type

• I-frame (information frame).

• Carries the actual FC information ( data and control)

• Includes N(S) and N(R) counters for sequencing and acknowledgment .

• S-frame (supervisory frame).

• RR ( Receiver Ready) – includes the N(R) counter to acknowledge sender frames.

• RNR ( Receiver Not Ready) – includes the N(R) counter to acknowledge sender frames and stop the transmitter.

• SREJ (Selective Reject) – indicates sequence numbers of dropped frames to feed the transmitter.

Recommended to send S-frames as high-priority (EF).

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FC PW congestion control - Selective

retransmission (cont.)

Retransmission protocol mechanism parameters

• T1-Poll Timeout

• T2 -Response Timeout

• K – window size

• N2 - Poll Retries

Protocol mechanisms ‘Poll’ and ‘final’ indication bits

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FC PW encapsulation

LAPB header

FC frame

L2 header

MPLS label

PW label

Control word (mandatory}

L2 CRC

FC PW

FC frame

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FC PW control word

Control word is REQUIRED

A – address bit part of the LAPB protocol indication

FRG – fragmentation is not supported

Length – short frame indication used (minimum 40bytes FC frame)

Sequence number – not used ( LAPB sequencing)

0 31

0 0 0 0 0 0 0 A FRGA Length Sequence Number

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FC PW LAPB header

N(S)

13579 0246810

17

16

18

19

20

21

22

23

24

25

26

27

28

29

30

31

15

14

13

12

11

0Type-I

Type-S

PN(R)

Reserved 1P/F

N(R) 0S-

Type

0 0 SR_RR

3 2Message

Type

0 1 Reserved

1 0 SR_RNR

1 1 SR_SREJ

S-Type Encoding

N(S): Transmitter send sequence number(transmitted frame S/N)

N(R): Transmitter receive sequencenumber (acknowledgement S/N)

P: Poll bit (1 = Poll)P/F: Poll/Final bit

1 = Poll when A = 11 = Final when A = 0

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Signaling of FC PW

PW type in FEC = FcPort

Control word is REQUIRED - C-bit in FEC must be set.

Interface parameters

• Four new Sub TLV – TBA

• Length of each 4 bytes

• Type = T1 , T2 ,N2 , K

• Both PE’s should agree on these value for succesful PW setup.

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Summary

Assign new PW Type “Fibre Channel port mode”

Assign parameter ID for interface parameters SUB

TLV

Draft-02 is ready for cross area review ?