As the Internet is widely used, high performance networks and systems prompts appearance of various applications and the appearance requests higher capacity resources. Recently, studies on grid are actively conducted to reorganize each computing resource, which used to be scattered for each application requesting these high capacity calculation resources, into a virtual high capacity resource by connecting to networks. The network needed in this grid environment has been progressed along with the WDM-base Lambda Network that can build a high-bandwidth network for relatively low cost. This article presents two ways that improve network performance on grid environment. First way is approach to reorganize the existing network into L2/OPN(Optical Private Network)by using Lambda networking to avoid traffic congestion. And second way is manage TCP windows buffer size to present a suitable TCP size for the Grid environment