以前公司網站用過Fundry，功能蠻強的，下列是該公司網站的產品介紹

Foundry's ServerIron family of application delivery and traffic management switches is the industry leader in high availability, acceleration, security and scalability for business-critical IP, Web and VoIP applications. The ServerIron provides a total solution for server load balancing, application (Layer 7) switching, server farm and application security, SSL acceleration, compression, and multi-site redundancy. The ServerIron products are almost exclusively used by over 2,000 of the world's most demanding organizations.

http://www.foundrynet.com/products/app-switch/

基本上 WAN LB ,有 Radware Linkproof ， Fiberlogic ， AscenLink，Q-balance等較有名氣，如果你只有兩條線路，功能要的又不高，現在很多UTM都有WAM LB功能。Foundry's ServerIron 是Server LB功能，與Radware AD(WSD)或F5的功能相同。

台灣 俠諾科技 QVM系列產品還有GQF 都很好用

有一家新軟設計的還不錯,
MH系列的,
如公司的人數不多,
MH-300是不錯的選擇,
且價格便宜約6500左右.

一般防火牆或路由器都有此設計了, trunk or trunking都是可以達到你所謂的Load balance. 其演算法大致有Round robin, Weighted round robin, least load first, spillover 等等。