Cheatsheet: Difference between revisions
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*Congestion Control |
*Congestion Control |
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;Slow Start - Exponential Increase |
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- Sender starts with cwnd = 1 MSS, Size increases 1 MSS each time one Ack arrives, Increases the rate exponentially(1,2,4,8....) until a threshold is reached |
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- Increases the cwnd Additively, When a “window” is Ack cwnd is increased by 1, Window = No of segments transmitted during RTT |
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- The increase is based on RTT, not on the number of arrived ACKs, Congestion window increases additively until congestion is detected |
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- If congestion occurs, Window size must be decreased, Sender knows about congestion via RTO or 3 Dup Acks received, Size of Threshold is dropped to half |
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*Tahoe |
*Tahoe |
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- '''Clark’s Solution''': Announce window size 0 till 1) enough space for 1 MSS in Buffer or Half Receive buffer is empty |
- '''Clark’s Solution''': Announce window size 0 till 1) enough space for 1 MSS in Buffer or Half Receive buffer is empty |
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- '''Delayed Acknowledgment''': Segment not acknowledged immediately, Sender TCP does not slide its window, reduces traffic, sender may unnecessarily retransmit, Not delay more than 500 ms. |
- '''Delayed Acknowledgment''': Segment not acknowledged immediately, Sender TCP does not slide its window, reduces traffic, sender may unnecessarily retransmit, Not delay more than 500 ms. |
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*Fast Retransmission |
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- If RTO has a larger value |
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- If sender receives four acknowledgments with same value (three duplicates) |
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- Segment expected by all of these Ack is resent immediately |
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= VPN Messages = |
= VPN Messages = |
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