Additions:
In the current code, hold acknowledgements and messages for up to 100ms before sending. In future it would be useful to be able to make this a function of the round-trip time, so we need an accurate delay time in the packets. Also, some messages may be less urgent than others.
Deletions:
Additions:
See OldPacketFormat for details of the current packet format and why it needs to change!
Additions:
==Coalescing==
In the current code, hold acknowledgements and messages for up to 100ms before sending. In future it would be useful to be able to make this a function of the round-trip time, so we need an accurate round-trip time in the packets. Also, some messages may be less urgent than others.
In the current code, hold acknowledgements and messages for up to 100ms before sending. In future it would be useful to be able to make this a function of the round-trip time, so we need an accurate round-trip time in the packets. Also, some messages may be less urgent than others.
Revision [2090]
Edited on 2007-06-08 18:53:28 by MatthewToseland [we need to be able to get an accurate RTT!]Additions:
- For each ack, the time in milliseconds that the ack was queued for, so we can accurately determine the round-trip time (2 bytes each).
Revision [1845]
Edited on 2007-03-06 19:33:09 by MatthewToselandAdditions:
- These are encoded as follows: The first (lowest) ack is a full 4-byte unsigned value; subsequent acks are 2 byte unsigned offsets from this (add to the first to get the ack number).
Deletions:
Revision [1844]
Edited on 2007-03-06 19:32:45 by MatthewToselandAdditions:
- These are encoded as follows: The first (lowest) ack is a full 4-byte unsigned value; subsequent acks are 2 byte offsets from this (add to the first one to get the ack number).
Revision [1843]
Edited on 2007-03-06 19:29:30 by MatthewToseland [support multiple acks, a bit more efficient]Additions:
Each packet contains:
- A count of the number of acks (unsigned byte).
- Zero or more acks. Each ack echoes the payload number of a packet received in the other direction.
- A count of the number of payload messages (unsigned byte). If there are no payload messages, skip the following.
- A 4-byte payload number. This number will be used by the receiver to acknowledge receipt of the packet, and unlike the unique sequence number it will not change if the packet is retransmitted. However, apart from retransmissions the payload number should be unique and non-wrapping.
- Freenet messages follow the payload number. Each message starts with 2 bytes indicating its type followed by 2 bytes indicating its length. Messages are never split across more than one packet.
- A count of the number of acks (unsigned byte).
- Zero or more acks. Each ack echoes the payload number of a packet received in the other direction.
- A count of the number of payload messages (unsigned byte). If there are no payload messages, skip the following.
- A 4-byte payload number. This number will be used by the receiver to acknowledge receipt of the packet, and unlike the unique sequence number it will not change if the packet is retransmitted. However, apart from retransmissions the payload number should be unique and non-wrapping.
- Freenet messages follow the payload number. Each message starts with 2 bytes indicating its type followed by 2 bytes indicating its length. Messages are never split across more than one packet.
Deletions:
Following the ack there is a 4-byte payload number. This number will be used by the receiver to acknowledge receipt of the packet, and unlike the unique sequence number it will not change if the packet is retransmitted. However, apart from retransmissions the payload number should be unique and non-wrapping. A value of -1 indicates that the packet does not contain a payload and does not need to be acknowledged.
Freenet messages follow the payload number. Each message starts with 2 bytes indicating its type followed by 2 bytes indicating its length. Messages are never split across more than one packet.
Revision [1825]
Edited on 2007-02-27 13:22:58 by MichaelRogersAdditions:
Each plaintext packet starts with a unique, non-wrapping //sequence number//. This is distinct from the //payload number// described below - if a packet is retransmitted, it will have the same payload number as the original, but a new sequence number.
Each packet contains an ack, a payload number, and zero or more Freenet messages. The ack echoes the payload number (**not** the unique sequence number) of a packet received in the other direction. A value of -1 indicates that the packet does not contain an ack.
Following the ack there is a 4-byte payload number. This number will be used by the receiver to acknowledge receipt of the packet, and unlike the unique sequence number it will not change if the packet is retransmitted. However, apart from retransmissions the payload number should be unique and non-wrapping. A value of -1 indicates that the packet does not contain a payload and does not need to be acknowledged.
Each packet contains an ack, a payload number, and zero or more Freenet messages. The ack echoes the payload number (**not** the unique sequence number) of a packet received in the other direction. A value of -1 indicates that the packet does not contain an ack.
Following the ack there is a 4-byte payload number. This number will be used by the receiver to acknowledge receipt of the packet, and unlike the unique sequence number it will not change if the packet is retransmitted. However, apart from retransmissions the payload number should be unique and non-wrapping. A value of -1 indicates that the packet does not contain a payload and does not need to be acknowledged.
Deletions:
Each plaintext packet starts with a unique, non-wrapping sequence number. This is distinct from the payload number described below - if a packet is retransmitted, it will have the same payload number as the original, but a new sequence number.
Each packet contains zero or more acks and zero or more Freenet messages. After the unique sequence number, there is one byte indicating the number of acks and one byte indicating the number of messages.
Each ack echoes the payload number (not the unique sequence number) of a packet received in the other direction. The first ack in a packet is 4 bytes long, echoing the complete payload number of the acknowledged packet. Each subsequent ack is 2 bytes long and should be interpreted as a positive offset relative to the first ack. As described above, the range of outstanding payload numbers should never exceed 2^16, so a 16-bit offset is adequate.
Following the acks, if the number of messages is greater than zero there is a 4-byte payload number. This number will be used by the receiver to acknowledge receipt of the packet, and unlike the unique sequence number it will not change if the packet is retransmitted. However, apart from retransmissions the payload number should be unique and non-wrapping.
