ndle. In the HTTP 1.0 case, the URL-based web switch in what has come to be known as delayed binding must first terminate the TCP session before it searches the HTTP request that contains the corresponding URL. This infor- mation is usually inside the second or third packet received by the web switch after the TCP session is established. Based on the URL thus found, the corresponding packets will be switched to the appro- priate destination server. The technique is actually called delayed binding because the connection with the correct server is not established until after the HTTP request has been received and parsed. This can be easily handled in software without any significant performance degradation when only one HTTP request is encountered per TCP session; however, it is impossible to contemplate in software in a massively scaled-load case such as the ones allowed by HTTP 1.1. SUMMARY In this chapter, we discussed the problem of classification as a follow-up to the problem of search that we covered in the previous chapter. We defined two broad categories of classification: one that involves classical lookup and forwarding procedures, which are done based on search and match according to bits found in a single field, and one that is focused on deep packet classification, which implies that the search and match process has to occur based on lookup and match against bit patterns appearing in multiple fields simultaneously. The former is key for classical routing/switching appli- cations. The latter is key for the new network world, where QoS, CoS, SLAs, and provisioning of dif- ferentiated services is the name of the game. When comparing alternatives for lookups or many other functions, the following key measures of merit deserve a close scrutiny: Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. CLASSIFICATION PROCESSORS 260 NETWORK PROCESS