cross-layer cooperation to boost multipath tcp performance in cloud networks matthieu coudron...
TRANSCRIPT
Cross-layer Cooperation to Boost Multipath TCPPerformance 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
OutlineI. Our goal
II. Multipath TCP presentation
III. Our proposition: Augmented MPTCP1) Overview
2) LISP presentation
3) Testbed & Results
2
Our goal
Increase goodput via multipath communications
Between DataCenters
Between endusers and DataCenters (DC)
3
4
Multipath TCP1. Introduction
2. Subflow management
MPTCP introductionDefined in RFC 6824 as a TCP extension
Emphasis on backwards compatibilityWorks with most middleboxes
Can send data concurrently on several subflowsSingle data stream transmitted at 51.8 Gbit/s.
Available in:Linux iOS7Citrix NetScaler
6
MPTCP introduction1. First acknowledges if destination is MPTCP
compliant during the 3 way handshake
2. Creates additional subflows according to path management mechanism
7
MPTCP path management
RFC 6182 states path management should be modular
By default 1 subflow per (src,dst) IPs2 IPsrc and 2 IPdst => 2x2=4 subflows
NB: Several subflows can originate from the same IP with different port numbers
8
1GB/s
1 IP 1 IP
100MB/s
100MB/s
By default 1 subflow
Wouldn’t 2 subflows be better ?
, need to follow different physical pathsNot necessarily...
9
• How many subflows to create ?• How to achieve proper forwarding ?
1GB/s
11
Our proposition: A-MPTCP1. Overview
2. Presentation of LISP3. Tesbed & Results
OverviewEnhance MPTCP path discovery with WAN
topology informationLISP can give edge path diversity information LISP can enable multipath WAN forwarding
Enforce per subflow forwardingBased on TCP ports in our caseRelying on edge multipath forwarding nodes
13
Location/Identifier Separation Protocol :
LISPDefined in RFC 6830
Tunneling protocol between edge routersAllows 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
14
15
Host EID « A »
Host EID « B »
1/ A wants to contact B
EID RLOCs
B RB1, RB2
RLOC RA
RLOC RB1
2/ RA retrieves RLOCs for B
3/ Packet from A encapsulated & forwarded to RB1
4/ RB decapsulates and forwards inner packet to B
RLOC RB2
Mapping Server
Our testbed
16
Our guess: Number of WAN paths = Number of RLOCs
17
1/ First subflow established
2/ Retrieves number of RLOCs
3/ Creation of 2nd subflow withSpecific source port number
G. Detal et al., « Revisiting Flow-Based Load Balancing: Stateless Path Selection in Data Center Networks »
(Subflow srcPortNumber) %2 = 0 (or 1)=>(Subflow srcPortNumber) %2 = 1 (or 0)
18
UD
P/L
ISP t
unnel
End-point C LISP router C LISP router S End-point S
1: SYN + MP_CAPABLE
1: SYN/ACK + MP_CAPABLE
1: ACK
SpecificKernel module
2: Request RLOCs
of EID S
Userspace daemon + lig program
3: Request relayed
to userspace
via Netlink
4: Sends Map-Request
5: Sends Map-Reply, i.e. list of RLOCs
6: Sends number of RLOCs
6: relays the information
7: Creation of additionnal subflows if needed
Results on 20 iterations
19
Results on 20 iterations
20
Results on 20 iterations
21
40% improval
3 subflows
22
ConclusionA-MPTCP gives significant gains in certain
conditionsDirectly proportional to the number of additional
WAN paths given by LISP
Available in opensource
Future workEnforce disjoint paths on the WAN segment via LISP
Traffic EngineeringFurther enhancement on the DC/LAN segment via
Cloud fabrics TE (SDN, OVS, TRILL-TE)
24
Want to try MPTCP ?1. Install the MPTCP kernel (Debian/Ubuntu)
http://multipath-tcp.org
2. Reboot
3. Go to www.amiusingmptcp.com
25
27
RB R1,R2
R3
2/ R1 looks for mapping
3/ R1 sends to next-hop R2
1/ R1 recieves packet
LISP Traffic Engineering
Number of subflowsHypothesis: LAN is not the bottleneck
Number of subflows N=Max(WAN diversity, LAN diversity)
N=Max(Product of EIDs, Product of RLOCs)
28
Subflow forwardingWe get N available WAN paths
We create N subflowsEach subflow i should have a i = srcPort % N
29
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
30
ReferencesThe fastest TCP connection with Multipath
TCPC. Paasch, G. Detal, S. Barré, F. Duchêne, O. Bonaventure
Revisiting Flow-Based Load Balancing: Stateless Path Selection in Data Center NetworksG. Detal et al.
31