Midterm Reports of MPTCP-Related Middlebox Behavior

Michio Honda, Keio University

Yoshifumi Nishida, Dyyno.Inc / WIDE project

Costin Raiciu, UCL

Mark Handley, UCL

MPTCP WG, Nov.10, 2010

79th IETF@Beijing

Today’s Data

Now we got data from more than 100 paths from around 20 countries

Today we show some of data in 81 paths obtained between 25 September and 22 October, 2010 36 (44.4%) home networks (Home-gateway+ISP) 12 (14.8%) university networks 11 (13.6%) cellular career (EDGE, 3G) 11 (13.6%) hotspots (e.g., hotel, public Wifi, hall) 6 (7.4%) company networks 4 (4.9%) hosting agents (e.g., Amazon EC2)

Middlebox Behavior MPTCP Should Care

TCP Options MP_CAPABLE, MP_DATA, MP_ACK, TIMESTAMP

Passed, removed, modified, zeroed (and at outgoing or incoming)?

Retransmission and Gapped Sequence When MPTCP retransmits the segment on another path,

retransmitting “TCP-level sequence number” might have different payload

Or, original sequence number might be skipped

TCP Options

Port 34343 3.7 % (3 out of 81) remove MP_CAP

All of them are cellular networks The same 3.7 % also remove MP_DATA

Port 80 12.3 % (10 out of 81) remove MP_CAP

4 cellular networks, 3 university networks, 3 hotspots Include all paths removing MP_CAP at port 34343

8.6 % (7 paths) remove MP_DATA Part of paths removing MP_CAP (3 cellular and 2 university 3

hotspots) 3.7 % (3 paths) didn’t deliver non-HTTP payload

The other part of paths removing MP_CAP (1 cellular, 1 univ.)

TCP Options (cont.)

Port 443 6.2 % (5 out of 81) remove MP_CAP

3 hotspots and 2 cellular networks All of these remove MP_CAP at port 80

The same 6.2 % also remove MP_DATA

Summary None of paths drops segments including MP_CAP or

MP_DATA 3.7 – 12.3 % of paths (depending on the port number)

remove MP_CAP or MP_DATA

Retransmission

Retransmission

Retransmissions with Different Payload

Port 34343 1.2 % (1 cellular network out of 81) discarded

retransmission of different payload Ack is advanced, but retransmitted payload has not reached

the receiver, because middlebox retransmitted

Port 80 7.4 % (6 out of 81) discarded retransmitted segment

including different payload, but Ack is advanced 3 hotspots, 2 cellular networks, and 1 home network One of them also does the same behavior at port 34343

1.2 % (1 out of 81) sent back RST against different payload retransmission 1 company network

Retransmissions with Different Payload (cont.)

Port 443 3.7 % (3 out of 81) discarded the retransmitted, but Ack is

advanced 3 hotspots Part of paths doing the same behavior at port 80

Summary 1.2 – 7.4 % of paths do not deliver retransmitted

segment, and the middlebox retransmits instead 1.2 % sends back RST against retransmission of different

payload for port 80

Retransmission

Gapped Sequence Number

Port 34343 1.2 % (1 cellular network out of 81) discarded the gapped

sequence 1.2 % (1 cellular network) replied Ack to resend the

correct sequence number Port 80

4.9 % (4 out of 81) discarded the gapped sequence 2 cellular networks, 1 company network and 1 home network

6.2 % (5 out of 81) replied Ack to resend the correct sequence number 3 hotspots and 2 cellular networks

Gapped Sequence Number (cont.)

Port 443 1.2 % (1 out of 81) discarded the gapped sequence

1 cellular network that also discards such segment at port 80 4.9 % (4 out of 81) replied Ack to resend the correct

sequence number 3 hotspots and 1 cellular networks (part of paths doing the

same behavior at port 80)

Summary 1.2 – 4.9 % of paths discard the gapped sequence 1.2 – 6.2 % of paths respond to resend the correct

sequence

Thank You for Your Contribution

We’re still collecting data, please send us log files from our experimental tool http://www.ietf.org/mail-archive/web/multipathtcp/curr

ent/msg01150.html If anybody stays in the hotel other than Shangri-la,

please run it at your room! If anybody can connect to Chinese 3G career via

iPhone (MyFi) or Android tethering, let us know!