routing & architecture comparison about: dcell, portland, vl2, bcube, mdcube point of views:...

Routing & Architecture

Comparison about:DCell , PortLand , VL2 , BCube , MDCube

Point of views:Goals , artecheture ,routing algorithm , fault tolerance ,broadcast and multicast ,evaluation and compare,

GoalsComparison about:DCell , PortLand , VL2 , BCube , MDCube

Goals DCell PortLand VL2

Scalable + incremental expansion

VM migration Support high huge data centers with uniform high capacity between servers

Fault-tolerance Adminstratornot need to configure any switch

Performances isolation between services

High network capacity

Any end host should efficiently communicate with others.

Ethernet layer-2 semantic

No forwarding loop

Failure detection

GoalsBCube MDCube

An architecture model for modular data center (MDC).

Solve the scalability problem on BCube with small cost by increasing the diameter and some change of routing algorithm.

High performance. For the same number of nodes, cost is significantly lower than BCube.

Robust, graceful performance degradation for both switch/server faults

ArtechetureComparison about:DCell , PortLand , VL2 , BCube , MDCube

artechetureDCell

artecheturePortLand

artechetureVL2

artecheture

DCell PortLand VL2

artecheture

cost high wiring cost(compare the expensive core switch)

--- ---

diameter 2^(k+1) – 1 6 6

artechetureBCube

Recursively define architecture

artechetureMDCube

Base on the architecture of BCube and some high speed fiber link. Each container is a BCube, and connect them with fiber. Usually one or two dimensions.

artechetureMDCube

artechetureBCube MDCube

artecheture

cost Only need cheap switches, but need a lot of switches when the number of nodes is very huge.

With the help of fiber, the number of switches is much lower than BCube. If the level of BCube is not high( 2 or 3 ), then the cost will be low even compare to other architecture (FatTree, DCell, etc.)

diameter 2* log p n p = number of ports in a switchn = number of nodesn= p^(k+1)k = level of Bcube

4k+3+D(2k+3)k is the level of BcubeD is the level of MDCube.

artechetureDiameter Compare

Architecture Diameter

Balance Tree 2k

Fat-Tree 6

DCell 2^(k+1) – 1

BCube K + 1

Routing Algorithm


routing algorithmDCell PortLand VL2

Divide-and-conquer

Two nodes src and dst that are in the same DCell(k) but in two different DCell(k-1)s. When computing the path from src to dst in a DCell k,we first calculate the intermediate link (n1; n2) that interconnects the two DCell(k-1)s.

Just as TCP Agent add the header


Divide-and-conquer

Two nodes src and dst that are in the same DCell(k) but in two different DCell(k-1)s. When computing the path from src to dst in a DCell k,we first calculate the intermediate link (n1; n2) that interconnects the two DCell(k-1)s.

routing algorithmDCell PortLan

d

VL2

Just as TCP


Agent add the header

routing algorithmBCube MDCube

Each packet header contains the routing path of the packet, the relay node don’t have to decide the next node.

One-to-one: One-to-one:

One-to-many: All-to-all:

One-to-all:

All-to-all:

routing algorithmBCube MDCube

Each packet header contains the routing path of the packet, the relay node don’t have to decide the next node.

One-to-one:For node A = (a0,…,ak), B = (b0,…,bk), we can route A to B by changing one bit of the ID each time. Since the ID of the node is at most k+1, the length of the routing path is at most 2( k+1).There are k+1 parallel path.

One-to-many: If node A want to send the data to x nodes, and x <= number of ports p, then we can construct a complete graph on these x+1 (including A) nodes by another x nodes as relays.

One-to-all: Can build (k+1) edge disjoint trees, and use them to broadcast

All-to-all: Can reach a good Aggregate Bottleneck Throughput (ABT) which is Θ(n)

routing algorithmBCube MDCubeOne-to-one: In the container, the routing algorithm is the same as BCube. When the path cross the container, correct the container ID one-by-one. The hops needed to intermediate the containers are 2D(k+1) + (D+1), D+1 is for the high speed link. This number plus the hop need in the two ends, which is 2*2(k+1), is the maximum hop needed in one routing path. There are k+1 parallel path.

All-to-all:Similar to BCube, MDCube has ABT =Θ(n)

Fault ToleranceComparison about:DCell , PortLand , VL2 , BCube , MDCube

fault toleranceDCell Local-reroute and Proxy, Local Link-state, Jump-up

for Rack Failure

PortLand Multi-rooted tree

VL2 Completely bipartite

BCube Yes, and has a good result on both switch and server fault.

MDCube Good because of BCube.

fault tolerance - BCube

Broadcast & Multicast


broadcast and multicastDCell : a sender delivers the broadcast packet to all its k +

1 neighbors when broadcasting a packet in a DCell(k).

PortLand :

nothing special

VL2 : not mentioned

BCube: Both can be reached. Do broadcast by constructing edge disjoint trees. Do multicast by using some relay nodes.

MDCube:

Similar to BCube.

Evalution & CompareComparison about:DCell , PortLand , VL2 , BCube , MDCube

evalution and compareDCell :

1. The link failure incurs only 1-second throughput degradation, while the node failure incurs a 5-second throughput outage that corresponds to our link-state timeout value.

2. The aggregate throughput of DCell was about 2 times faster than Tree.

evalution and comparePortLand :

Convergence time : 70ms (TCP : 200ms)Scalability : 100ARPs/sec/host 30000

nodes control traffic 400Mbps; Core required : 70

VM migration : throughput drops to zero in 200-600ms, fully recovered after 32s

evalution and compareVL2 :

Uniform high capacityVLB fairnessPerformance IsolationDirectory-system performance

evalution and compareBCube:

evalution and compareMDCube:

routing & architecture comparison about: dcell, portland, vl2, bcube, mdcube point of views:...

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