The state of the art in locally distributed Web-server systems

This Web page contains update information about Web clusters and products as described in the paper:
Commercial products and research prototypes are classified as follows: The latter class of architectures differs from the previous ones in that the Virtual IP address is not assigned to a single front-end device (i.e., the Web switch) but shared by all server nodes.

Commercial products and research prototypes based on a layer-4 Web switch

Table 1 classifies some commercial products and research prototypes that work at the TCP/IP layer. Some products appear in multiple table entries because they can be configured to support more than one request routing mechanism.

Table 1: Layer-4 Web clusters.
Two-way One-way
Packet double-rewriting Packet single-rewriting Packet tunneling Packet forwarding
Cisco's LocalDirector  [8] TCP Router  [12] Linux Virtual Server  [19] IBM Network Dispatcher  [17]
Magicrouter [2]     Linux Virtual Server  [19]
Linux Virtual Server  [19]       F5 Networks' BIG-IP  [13]
LSNAT [27]     LSMAC  [15]
F5 Networks' BIG-IP  [13]     Intel's NetStructure Traffic Director [18]*
Foundry Networks' ServerIron [14]     Nortel Networks' Alteon 180 [23]
IBM Network Dispatcher  [17]     Radware's WSD Pro [25]
Coyote Point's Equalizer  [10]     Foundry Networks'ServerIron [14]
Allot's NetBalancer [1]     ONE-IP [11]

* Intel has announced the discontinuation of this product line.

Commercial products and research prototypes based on a layer-7 Web switch

Table 2 classifies the cluster-based Web systems that work at the application layer. Some products listed herein have already been considered in Table 1 as they can be configured to support both layer-4 and layer-7 routing mechanisms.

Table 2: Layer-7 Web clusters.
Two-way One-way
TCP gateway TCP splicing TCP handoff TCP connection hop
IBM Network Dispatcher proxy-level CBR  [17] Nortel Networks' Alteon Web OS  [23] ScalaServer [5,24] Resonate's Central Dispatch [26]
CluBWeb [7] Lucent's Web Switch  [9,20] [28]  
HACC [32] Cisco's CSS [8] CluBWeb [3]  
  Foundry Networks' ServerIron [14]    
  F5 Networks' BIG-IP [13]    
  Radware's WSD Pro [25]      
  Zeus's Load Balancer [31]    
  L5 [4]    
  Array Networks' Array 500 [6]    
  IBM Network Dispatcher kernel-level CBR [17]    

Commercial products and research prototypes for virtual Web clusters

Table 3 classifies the virtual Web clusters on the basis of the MAC address assignment to the server nodes.

Table 3: Virtual Web clusters.
Unicast MAC address Multicast MAC address
Microsoft Network Load Balancing  [21] Microsoft Network Load Balancing  [21]


Allot Communications Ltd.

E. Anderson, D. Patterson, and E. Brewer.
The Magicrouter, an application of fast packet interposing., May 1996.

M. Andreolini, E. Casalicchio, M. Colajanni, and M. Mambelli.
Performance analysis of layer-7 switches for cluster-based Web servers.
Technical Report RR-01.24, Univ. of Rome Tor Vergata, Computer Engineering Dept., Nov. 2001.

G. Apostolopoulos, D. Aubespin, V. Peris, P. Pradhan, and D. Saha.
Design, implementation and performance of a content-based switch.
In Proceedings of the 19th IEEE International Conference on Computer Communications (INFOCOM 2000), pages 1117-1126, Tel-Aviv, Israel, Mar. 2000.

M. Aron, P. Druschel, and Z. Zwaenepoel.
Efficient support for P-HTTP in cluster-based Web servers.
In Proceedings of the 1999 USENIX Annual Technical Conference, pages 185-198, Monterey, CA, June 1999.

Array Networks Inc.

E. Casalicchio and M. Colajanni.
A client-aware dispatching algorithm for Web clusters providing multiple services.
In Proceedings of the 10th International World Wide Web Conference, pages 535-544, Hong Kong, May 2001.

Cisco Systems Inc.

A. Cohen, S. Rangarajan, and H. Slye.
On the performance of TCP splicing for URL-aware redirection.
In Proceedings of the 2nd USENIX Symposium on Internet Technologies and Systems, Boulder, CO, Oct. 1999.

Coyote Point Systems Inc.

O. P. Damani, P. E. Chung, Y. Huang, C. Kintala, and Y.-M. Wang.
ONE-IP: Techniques for hosting a service on a cluster of machines.
Computer Networks, 29(8-13):1019-1027, 1997.

D. M. Dias, W. Kish, R. Mukherjee, and R. Tewari.
A scalable and highly available Web server.
In Proceedings of the 41st IEEE Computer Society International Conference, pages 85-92, San Jose, CA, Feb. 1996.

F5 Networks Inc.

Foundry Networks Inc.

X. Gan and B. Ramamurthy.
LSMAC: An improved load sharing network service dispatcher.
World Wide Web, 3(1):53-59, Jan. 2000.

G. S. Hunt, G. D. H. Goldszmidt, R. P. King, and R. Mukherjee.
Network Dispatcher: A connection router for scalable Internet services.
Computer Networks, 30(1-7):347-357, 1998.

IBM WebSphere Edge Server.

Intel NetStructure.
Note that Intel has announced the discontinuation of this product line.

Linux Virtual Server project.

Lucent Technologies.
Lucent Web Switch.

Network Load Balancing.

NetScaler Inc.
Netscaler's Request Switch.

Nortel Networks Ltd.
Nortel Networks Web OS.

V. S. Pai, M. Aron, G. Banga, M. Svendsen, P. Druschel, W. Zwaenepoel, and E. M. Nahum.
Locality-aware request distribution in cluster-based network servers.
In Proceedings of the 8th ACM Conference on Architectural Support for Programming Languages and Operating Systems, pages 205-216, San Jose, CA, Oct. 1998.

Radware Inc.

Resonate Inc.

P. Srisuresh and D. Gan.
Load sharing using IP Network Address Translation.
RFC 2391, Aug. 1998.

W. Tang, L. Cherkasova, L. Russell, and M. W. Mutka.
Modular TCP handoff design in STREAMS-based TCP/IP implementation.
In Proceedings of the 1st International Conference on Networking, Lecture Notes in Computer Science 2049, pages 71-80, Colmar, France, July 2001.

S. Vaidya, K. Christensen.
A single system image server cluster using duplicated MAC and IP addresses.
In Proceedings of the IEEE 26th Conference on Local Computer Networks, pages 206-214, Tampa, FL, Nov. 2001.

C.-S. Yang and M.-Y. Luo.
A content placement and management system for distributed Web-server systems.
In Proceedings of the 20th IEEE International Conference on Distributed Computing Systems, pages 691-698, Taipei, Taiwan, Apr. 2000.

Zeus Technologies Ltd.

X. Zhang, M. Barrientos, J. B. Chen, and M. Seltzer.
HACC: An architecture for cluster-based Web servers.
In Proceedings of the 3rd USENIX Windows NT Symposium, pages 155-164, Seattle, WA, July 1999.

Maintained by Valeria Cardellini
Last updated: February 21, 2003.