Version 2 (modified by kais, 6 years ago) (diff)


What I'm working on?

Prototyping of data processing part in GSTAR routing protocol, namely, reliable hop-by-hop large chunk transfer.

Work Log

Jun 1st Got the host-router-host latency test configuration running, but still need to make sure click is handling all packets. Discussed about data process implementation with Kiran.

Jun 8th Compiled the code for aggregator and segmentor with ACK. Testing it on orbit...

Jun 13th tested: when packets get lost, sender can retransmit those packets.

July 8th worked out sender-router-receiver configuration on Orbit. Sent a 1GB file from sender via two hops to receiver.

Comparison of MobilityFirst vs. Hop protocol

MobilityFirst Hop
Signaling Chunk SYN msg separate signaling msg: BSYN
Chunk transfer Yes, sending data in the unit of chunk Yes
Bitmap ACK Yes Yes
ACK loss handling similar with Hop, CSYN waiting for ACK timeouts, resend BSYN
When to ACK received CSYN received BSYN
What to ACK bitmap of whole chunk or a portion of chunk bitmap of whole chunk
Data caching (short-term) Yes Yes
Data caching (long-term) Yes No
Virtual retransmission Yes
ACK withholding Yes Yes
Backpressure control Yes Yes

Signaling process in one hop reliable data transfer

Signaling process for one hop reliability

*Sender initiates chunk transfer by sending a CSYN message, receiver responds with an ACK with a bitmap identifying the receiving status

*After receiving an ACK, sender begins sending a chunk of data packets, and then send another CSYN asking for ACK.

*The transfer of this chunk terminates when the received bitmap says all packets are received.

*Every time a CSYN is sent, a timer will be set. If an ACK is not received before the timeout, the CSYN will be resent.

One-hop file transfer evaluation

Notes: For the same file, a smaller chunk size corresponds to larger number of chunks, therefore more incurred latency on signaling. This suggests reducing signaling to improve performance (maybe doesn't need signaling for every chunk).

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