Adaptive Load Balancing based on IP Fast Reroute to Avoid Congestion Hot-spots Masaki Hara, Takuya Yoshihiro 2011 IEEE International Conference on Communications

Adaptive Load Balancing based on IP Fast Reroute to Avoid Congestion Hot-spots

Masaki Hara, Takuya Yoshihiro2011 IEEE International Conference on Communications (ICC)

• Introduction• Load balancing mechanisms using IP fast reroute

scheme SBR• Traffic simulation• Concluding remarks

Outline



Introduction

• Recent growth of the Internet and the rapid increase of user traffic require more bandwidth and communication quality for infrastructure networks. To make the most of existing network resources, several traffic engineering (TE) techniques have been proposed so far.

• Traffic engineering– IP based TE– MPLS based TE

Introduction (cont.)

• Multiprotocol Label Switching (MPLS)– Reduces network complexity– Compatible with existing network technology – Reduce network cost– To ensure QoS and security– Traffic engineering capabilities


Expensive

• First presented the method to optimize link metrics. They formulate the link metric optimization problem by means of linear programming which compute the optimal link metrics to make the most of network resources assuming that traffic demand among every pair of nodes is given.

• Their work also presented that IP based TE achieves the similar level of load balance performance compared to MPLS based TE techniques.

[2] B. Forts and M. Thorup, “Internet Traffic Engineering by Optimizing OSPF Weights,” in Proc. INFOCOM2000, pp.519–528, 2000

• In IP based shortest-path scheme, traffic tends to be concentrated on particular links or nodes since the shortest-paths tend to use the common low-cost links.


• Their simulation demonstrated that under the traffic variation coming from link failure, IP based TE often brings severe congestion hotspots caused of concentration of shortest paths, while MPLS based TE cause much less congestion.

• This result implies that there is still room to improve IP based TE techniques.

[3] S. Dasgupta, J.C.de Oliveira, and J.P. Vasseur, “A Performance Study of IP and MPLS Traffic Engineering Techniques under Traffic Variations,” IEEE Globecom2007, pp.2757-2762, 2007.

• In practice, the optimization process requires the mechanisms to measure the traffic demand, to share the measured information among all nodes, and to re-compute the new distribution paths. This process would results in losing sensitivity for dynamic transition of traffic.

[4] A.K. Mishra and A. Sahoo, “S-OSPF: A Traffic Engineering Solution for OSPF based Best Effort Networks,” In Proc. IEEE Globecom 2007, pp.1845–1849, 2007.[5]M. Anti´c and A. Smiljani´c, “Oblivious Routing Scheme Using Load Balancing Over Shortest Paths,” In Proc. IEEE ICC 2008, pp.5783–5737, 2008.


• In this paper, as another approach of load balancing in IP routing schemes, we propose an IP fast reroute based load balancing mechanisms

IP Fast Reroute

The approach of load balancing using IP fast reroute has several good characteristics :

• This work is the first specific mechanism description and the first investigation on the performance of IP fast reroute based load balancing mechanisms.




Load Balancing Mechanisms Using IP Fast Reroute Scheme SBR

• SBR (Single Backup-table Rerouting)– SBR is an IP fast reroute scheme which recovers every

single link failure with low overhead, i.e., two 1-bit flags in packet header and one additional routing table.

• Two 1-bit flags– b-flag (1-bit) : 0/1– r-flag (1-bit)

• One additional routing table = Two routing table – primary routing table– backup table (backup/ switch)

Single Backup-table Rerouting

Single Backup-table Rerouting(cont.)


y

u v

d

x

w(b-flag, r-

flag)

(0, n/a)

packet

destination


y

u v

d

x

w(b-flag, r-

flag)

(0, n/a)

packet

destination


y

u v

d

x

w

Jam

(b-flag, r-flag)

(0, n/a)

packet

destination


y

u v

d

x

w

Jam

(b-flag, r-flag)

(0, n/a)

packet

(1, n/a)(0,

val.)u → x → u → v → w → y → d

destination


y

u v

d

x

w

Jam

destination

(b-flag, r-flag)

packet

Jam

(0, n/a)(1, n/a)(0,

val.)

The Proposed Load Balancing Mechanisms

Original Router

Incoming packets

Router

Router decision using

b-flag and r-flag

Output queue

Output queue

To backup next-hop

To primary next-hop

Proposed Router

Incoming packets

Router

Router decision using

T1 and T2

Output queue

Output queue

To backup next-hop

To primary next-hop

T1

T1

T2

T2

q(b)

q(p)

Original flag

y

u v

d

x

w

destination

(b-flag, r-flag)

(0, n/a)

packet

Proposed flag

y

u v

d

x

w

destination

(b-flag, r-count)

(0, n/a)

packet

Formal Forwarding Process at Each Router in The Proposed Method


y

u v

d

x

w

Jam

destination

(b-flag, r-count)

packet

Jam

(0, 0)(1, 0)(0, 1)(1, 1)(1, 1)(0, 2)MAX r-count = 3



Traffic Simulation

• ns-2 simulator• Network topology of Waxman model with 30 and 100 nodes• topology generator BRITE• 10% of the links randomly as “bottleneck” links which bandwidth is

50Mbps • normal link bandwidth is 100 Mbps• 10Mbps CBR flows with 1-kilobyte packets • source and destination nodes are selected randomly• Output queue length is 50 packets. • Threshold T1 is 100% and T2 is 10% • The number of maximum allowed detouring is set to 3.• Simulation is done by generating 10 topologies • for each topology we select different two sets of bottleneck links and

traffic patterns• average values to show the results

Simulation Setup

Fig. 3. Improvement of Throughput with Variation of Traffic Load

Fig. 4. Ratio of Packets Rescued by Detouring

Fig. 5. The Specification of Number of Detour to Reach Destination (Case of 30 Nodes)

Fig. 6. The Specification of Number of Detour to Reach Destination (Case of 100 Nodes)

Fig. 7. Increase of Packet Delay of Shortest-Path Traffic

Fig. 8. Ratio of Throughput of Shortest-Path Traffic



Concluding Remarks

• In this paper we investigated a load balancing technique based on IP fast reroute mechanisms. Our method detours packets only when the packets meet congestion to make the most of vacant resources of networks.

Concluding Remarks (cont.)

• Note that since the number of flows transmitted is the same, the amount of shortest-path traffic is the same in both OSPF and the proposed.

Weekly Sentence

because ≥ for since > as

詞性

從屬連接詞並列連接詞從屬連接詞從屬連接詞

用法

1.可用於回答 why 提出的問題、引導表語從句、用於強調句等，而其余三者均不行

1.它有時可表示因果關系( 通常要放在主句之後，且可與 because 換用 ) ；有時不表示因果關系，而是對前面分句內容的解釋或推斷 ( 也要放在主句之後，但不能與 because 換用 )

1.原因都是人們已知的，即對已知事實提供理由，而不是表示直接原因。 since 比 as 語氣稍強，且比 as 略為正式，它們引導的從句通常放在主句之前，有時也放在主句之後

2. since 可用於省略句，而其他三者不行

例句

1. It is because he is honest that I like him

1. The ground is wet ， for ( ＝ because) it rained last night

2. It must have rained last night ， for the ground is wet this morning

1. Since you are wrong, you should apologize.

2. Since so, I have nothing to say.

1. As you weren’t there, I left a message.

Documents

Adaptive Load Balancing based on IP Fast Reroute to Avoid Congestion Hot-spots Masaki Hara, Takuya Yoshihiro 2011 IEEE International Conference on Communications