Transcript Slides - IEEE CloudNet 2013

Cross-layer Cooperation to Boost Multipath TCP
Performance in Cloud Networks
Matthieu Coudron (LIP6), Stefano Secci (LIP6),
Guy Pujolle (LIP6), Patrick Raad (NSS), Pascal Gallard (NSS)
IEEE Cloudnet 2013, 12 Nov. 2013, San Francisco
Outline
I.
Our goal
II. Multipath TCP presentation
III. Our proposition: Augmented MPTCP
1) Overview
2) LISP presentation
3) Testbed & Results
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Our goal
Increase goodput via multipath communications
 Between DataCenters
 Between endusers and DataCenters (DC)
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Multipath TCP
1. Introduction
2. Subflow management
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MPTCP introduction
 Defined in RFC 6824 as a TCP extension
 Emphasis on backwards compatibility
 Works with most middleboxes
 Can send data concurrently on several subflows
 Single data stream transmitted at 51.8 Gbit/s.
 Available in:
 Linux
 iOS7
 Citrix NetScaler
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MPTCP introduction
1. First acknowledges if destination is MPTCP compliant
during the 3 way handshake
2. Creates additional subflows according to path
management mechanism
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MPTCP path management
 RFC 6182 states path management should be modular
 By default 1 subflow per (src,dst) IPs
 2 IPsrc and 2 IPdst => 2x2=4 subflows
 NB: Several subflows can originate from the same IP with
different port numbers
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• How many subflows to create ?
• How to achieve proper forwarding ?
By default 1 subflow
100MB/s
1GB/s
1GB/s
100MB/s
1 IP
1 IP
Wouldn’t 2 subflows be better ?
Not necessarily... , need to follow different physical paths
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Our proposition: A-MPTCP
1. Overview
2. Presentation of LISP
3. Tesbed & Results
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Overview
 Enhance MPTCP path discovery with WAN topology
information
 LISP can give edge path diversity information
 LISP can enable multipath WAN forwarding
 Enforce per subflow forwarding
 Based on TCP ports in our case
 Relying on edge multipath forwarding nodes
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Location/Identifier
Separation Protocol : LISP
 Defined in RFC 6830
 Tunneling protocol between edge routers
 Allows us to get the WAN path diversity
 IPs classified in 2 groups:
 Endpoint IDentifier (EID)
 Routing Locators (RLOCs)
 EID associated to RLOC(s) via a mapping system
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Mapping Server
EID
RLOCs
B
RB1, RB2
4/ RB decapsulates and
forwards inner packet to B
2/ RA retrieves RLOCs for B
1/ A wants to contact B
RLOC RA
RLOC RB1
3/ Packet from A
encapsulated & forwarded to RB1
RLOC RB2
Host EID « B »
Host EID « A »
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Our testbed
Our guess: Number of WAN paths = Number of RLOCs
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1/ First subflow established
2/ Retrieves number of RLOCs
3/ Creation of 2nd subflow with
Specific source port number
(Subflow srcPortNumber) %2 = 0 (or 1)
=>(Subflow srcPortNumber) %2 = 1 (or 0)
G. Detal et al., « Revisiting Flow-Based Load Balancing: Stateless
Path Selection in Data Center Networks »
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End-point C
LISP router C
LISP router S
End-point S
UDP/LISP tunnel
Userspace daemon Specific
Kernel module
+ lig program
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Results on 20 iterations
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Results on 20 iterations
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Results on 20 iterations
40% improval
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3 subflows
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Conclusion
 A-MPTCP gives significant gains in certain conditions
 Directly proportional to the number of additional WAN paths
given by LISP
 Available in opensource
 Future work
 Enforce disjoint paths on the WAN segment via LISP Traffic
Engineering
 Further enhancement on the DC/LAN segment via Cloud
fabrics TE (SDN, OVS, TRILL-TE)
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Want to try MPTCP ?
1. Install the MPTCP kernel (Debian/Ubuntu)
 http://multipath-tcp.org
2. Reboot
3. Go to www.amiusingmptcp.com
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Source code available on :
http://github.com/teto/xp_couplage
[email protected]
LISP Traffic Engineering
1/ R1 recieves packet
2/ R1 looks for mapping
3/ R1 sends to next-hop R2
RB
R1,R2
R3
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Number of subflows
 Hypothesis: LAN is not the bottleneck
 Number of subflows N=Max(WAN diversity, LAN diversity)
 N=Max(Product of EIDs, Product of RLOCs)
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Subflow forwarding
 We get N available WAN paths
 We create N subflows
 Each subflow i should have a i = srcPort % N
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Coupled Congestion Control
 Shared global window
 The TCP subflows are not independant and their
congestion windows are coupled
 Try to use the least congested paths
 Probe other paths as well
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References
 The fastest TCP connection with Multipath TCP
C. Paasch, G. Detal, S. Barré, F. Duchêne, O.
Bonaventure
 Revisiting Flow-Based Load Balancing: Stateless
Path Selection in Data Center Networks
G. Detal et al.
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