What I'm working on?

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

TODO List

• Add storage part(ordering when rescheduling stored chunks)
• Router should keep a window of (RECVD - SENT)<CONST
• Multiple flows: fairness

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).

Click diagram for sender-router-receiver config

Sender Router Receiver

./configure --disable-linuxmodule --enable-local
make elemlist
make install

Command to visualize a config. file:

tools/click−flatten/click−flatten ping−1.click | tools/click−viz/click−viz | dot −Tpng > ping−1.png