香港六合彩 » SlideShare

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,就象某个时刻做的那个梦一样,看不见对方的脸,只有体温和影子,如同跟未知名的蛇类做合二为一的相融.我虽然闭着眼,但手指更加清晰的探清了所要到达的脉络,两只眼睛,一个鼻子,一张嘴巴,耳朵,脖子,胸脯,小腹以及纤腰.我喘着粗气,迎面而来的是令人麻醉的大口呼吸,我的嘴巴不敢停止,上前咬住,慌乱的探索,紧张不安的等待迎合,全身无力又好似力气无穷,双脚麻木又好似千钧一腿.我知道与我一起体验快乐的这个人叫李雪,曾经屡次出现在我梦中的一个神秘女孩,我有了拥有香港六合彩的欲望,我膨胀的不行,香港六合彩已经除去所有遮挡之物,象亚当复娃游离世间,象天与地迫切相合,我的脑子出现大量影视画面,想成为一个真正男儿征服怀中女子,高傲的宣布我从今走走向成熟.我感觉到什么湿湿的东西,冰凉入肺,从鼻尖传递到我心间,我忽地挣开眼,意识逐渐清晰,记忆开始复苏.香港六合彩、香港六合彩、香港六合彩怎么是小花?
香港六合彩是小花,我明白过来,决不是我一腔情愿的李雪,若干分钟前给香港六合彩过的生日,喝了几杯老酒,然后无

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  • Marker (Protocol Data Unit) Aligned Framing, or MPA.
  • 香港六合彩 » SlideShare

    1. 1. MPA update (-00) ( Marker PDU Aligned Framing for TCP) draft-ietf-rddp-mpa-00 Paul R. Culley HP 11-11-2003
    2. 2. Draft-ietf-rddp-mpa-00 <ul><li>Now a workgroup document slated as “informational RFC” </li></ul><ul><li>In 4 th revision </li></ul><ul><li>Few comments received </li></ul>
    3. 3. Changes <ul><li>Changed &quot;Start Key&quot; to two separate startup frames to facilitate identification of incorrect Active/Active startup. </li></ul><ul><li>Changed Active/Passive nomenclature to Initiator/Responder to reduce confusion with TCP startup and verbs doc (which used opposite sense). </li></ul><ul><li>Added &quot;Private Data&quot; to the startup key sequences. This also required describing the motivation and expected usage models along with some interface hints. Removed the &quot;Private data“ stuff from appendix. </li></ul><ul><li>Added example &quot;Immediate&quot; startup with TCP and explanation. </li></ul>
    4. 4. Issues <ul><li>One comment that Active/Active startup should be supported and it should be “easy”. </li></ul><ul><ul><li>“ All that is required is to define a third value for &quot;instant start&quot;, which each side sends *and* expects to receive.” </li></ul></ul><ul><li>This makes a “dual stack” implementation harder, because there is not a specific point where the legacy TCP stack can transition to the TCP/MPA/DDP stack. </li></ul><ul><ul><li>Authors believe that not supporting this makes for easier implementations that avoid several difficult “races”. </li></ul></ul>
    5. 5. Issues <ul><li>One comment that MPA should be allowed to send FPDUs before startup frame is received. </li></ul><ul><ul><li>Before you know how to set marker/CRC modes! </li></ul></ul><ul><ul><li>Argument that FPDUs with wrong settings can be dropped. </li></ul></ul><ul><li>Don’t believe this should be allowed. </li></ul><ul><ul><li>Adds unnecessary complexity to all receivers to deal with “incorrect” FPDUs without tearing down connection. </li></ul></ul><ul><ul><ul><li>DDP Draft currently requires connection teardown. </li></ul></ul></ul><ul><ul><li>Alternate is to allow mismatched settings to tear down connection… </li></ul></ul>
    6. 6. Issues <ul><li>One Comment that sending FPDUs should be allowed at least as soon as the “Start frame” is received at each end. </li></ul><ul><li>Currently the “Responder mode” endpoint is required to wait until the first FPDU is received. </li></ul><ul><ul><li>This requirement was included to simplify “dual stack” implementations, in that the initiator could switch stacks without concern for an early FPDU (avoiding a race). </li></ul></ul>
    7. 7. Minor Issues <ul><li>One Comment indicated that we missed a “must”: MPA must pass any received private data to the ULP. </li></ul><ul><li>One Comment suggested that the difference between Initiator and Responder Startup frames should be more than one bit. </li></ul><ul><li>Comment that reference to “verbs” draft should be fixed or removed. </li></ul><ul><li>Comment that SCTP’s CRC reference is not correct. </li></ul><ul><li>Comment that difference between IPV4 and IPV6 headers should be noted when calculating FPDU lengths. </li></ul>
    8. 8. IWarp Startup sequence* Initiator ULP says “Are you OK with going to iWARP?” in streaming mode This message is optional! ULP gets message; enables MPA in “Responder” mode and sends optional last streaming “Yes, I'm in iWARP now”, message. MPA waits for incoming <MPA Request Frame> ULP gets message; enables MPA in “Initiator” mode. MPA sends “MPA Request Frame” and waits for the “MPA Reply Frame” Responder MPA gets MPA Reply Frame, Consumer binds MPA to DDP, MPA and DDP go into full operation. First iWARP message sent by RNIC (When WQE is posted) MPA gets MPA Request Frame, Consumer binds MPA to DDP, MPA sends MPA Reply Frame, FPDU decoding enabled. MPA gets first FPDU; Goes into Full iWARP mode. First iWARP message sent by RNIC (When WQE is posted) * No private data interactions shown
    9. 9. IWarp Startup sequence with TCP MPA gets MPA Reply Frame, passes “private data” to consumer, Consumer binds MPA to DDP, MPA and DDP go into full operation. First iWARP message sent by RNIC (When WQE is posted) Initiator TCP SYN sent TCP to “Established”, Consumer enables MPA in responder mode, MPA waits for incoming <MPA Request Frame> As TCP enters “established”, Consumer enables MPA in “Initiator” mode. MPA sends “MPA Request Frame” with “private data” and waits for the “MPA Reply Frame” Responder MPA gets MPA Request Frame, passes “private data” to consumer, Consumer binds MPA to DDP, MPA sends MPA Reply Frame, FPDU decoding enabled. MPA gets first FPDU; Goes into Full iWARP mode. First iWARP message sent by RNIC (When WQE is posted) TCP gets SYN Sends SYN-Ack TCP gets SYN-Ack Sends Ack Note Note: The Ack may be in the same segment as the MPA Request Frame in some implementations!
    10. 10. MPA Request Frame <ul><li>Key: The 16 char text string “MPA ID Req Frame” </li></ul><ul><li>M: Marker bit (0=No marker, 1=Marker) </li></ul><ul><li>C: CRC bit (0=No CRC desired, 1=CRC required) </li></ul><ul><li>Rev: MPA revision (0 for this version) </li></ul><ul><li>Res: Reserved, transmit as zero, not checked </li></ul><ul><li>PD_Length: Length of any private data </li></ul><ul><li>Private Data: ULP defined field </li></ul>Key (“MPA ID Req Frame”) 16 bytes M 1b C 1b Res(0) 6b Rev (0) 8b PD_Length 16b Private Data “PD_Length” bytes
    11. 11. MPA Response Frame <ul><li>Key: The 16 char text string “MPA ID Rep Frame” </li></ul><ul><li>M: Marker bit (0=No marker, 1=Marker) </li></ul><ul><li>C: CRC bit (0=No CRC desired, 1=CRC required) </li></ul><ul><li>Rev: MPA revision (0 for this version) </li></ul><ul><li>Res: Reserved, transmit as zero, not checked </li></ul><ul><li>PD_Length: Length of any private data </li></ul><ul><li>Private Data: ULP defined field </li></ul>Key (“MPA ID Rep Frame”) 16 bytes M 1b C 1b Res(0) 6b Rev (0) 8b PD_Length 16b Private Data “PD_Length” bytes
    12. 12. Faq <ul><li>Why must Initiator side wait for “MPA Reply Frame” before sending FPDU? </li></ul><ul><ul><li>Ensures that BOTH ends are MPA/DDP endpoints before lots of data are sent. </li></ul></ul><ul><ul><ul><li>only the “MPA Reply Frame” would be received by a non-MPA endpoint </li></ul></ul></ul><ul><ul><li>MPA knows about marker and CRC modes </li></ul></ul><ul><ul><ul><li>So first (few) FPDUs are not different (with Marker/CRC) </li></ul></ul></ul>
    13. 13. Faq <ul><li>Why can’t Responder side send FPDUs as soon as “MPA Request Frame” is received? </li></ul><ul><ul><li>Allows simpler “Initiator” side receiver design; “MPA Request Frame” and first FPDU cannot end up in same segment; allows time after Request frame arrives to reconfigure or switch stacks for FPDU reception. </li></ul></ul>
    14. 14. Faq <ul><li>How are Active/Active Peer to Peer connections dealt with? </li></ul><ul><ul><li>If Peer to Peer connections are used, they MUST use some ULP mechanism to identify the MPA/DDP “Active” or “Passive” sides. </li></ul></ul><ul><ul><li>Can be based on Unique endpoint name, or </li></ul></ul><ul><ul><li>Can be some GUID in “private data”, or </li></ul></ul><ul><ul><li>Can be a full streaming negotiation </li></ul></ul>
    15. 15. End

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