Cheatsheet: Difference between revisions
→TCP Topics Hierarchy
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= TCP
*Congestion Control
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- If sender receives four acknowledgments with same value (three duplicates)
- Segment expected by all of these Ack is resent immediately
*Persistence Timer
- Issue of Deadlock created by Lost Ack, used to reset Window size 0 advertized earlier, is resolved by this timer
- Sending TCP sends a special segment(1 byte of new data) called Probe, causes the receiving TCP to resend Ack
- If no reply, another probe is sent and value of persistence timer is doubled and reset
- Sender continues sending probes, doubling, resetting value of persistence timer until it reaches a threshold(generally 60s)
- After that the sender sends one probe segment every 60s until the window is reopened
= VPN Messages =
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