 Voice control Telnet/SSH HTTP to/from 10.10.100.100 ---to be determined--- Everything else (default-best effort) Notice I've kept telnet/SSH above the call-center traffic. Remember, we're keeping that as our ace in the hole for when there's an outage. Our next consideration is email, which can eat up a lot of bandwidth on a network. In a Microsoft Exchange environment, email is stored in files called postoffice (.pst) files. You may have users on one end of a link with their .pst files stored on a file server in a remote office. Often, the execs will have 1 GB .pst files that get opened across the WAN. What's more, all the users who are configured this way probably come in around the same time, and request their huge .pst files at the same time every morning, potentially bringing the network to a crawl. Still, the executives insist that email should be prioritized, SO we'll put it just above the default queue: Voice RTP Voice control Telnet/SSH HTTP to/from 10.10.100.100 ---to be determined--- Email (SMTP, POP, IMAP, Exchange) Everything else (default-best effort) In my experience, email problems can usually be attributed to poorly enforced (or even nonexistent) acceptable use policies. For example, one user sending an email with a 20 MB attachment to everyone in the company can cause a significant impact on the network. Chapter 30: Designing a QoS Scheme Removing the placeholder, we now have the following final list of priorities, in order: Voice RTP Voice control Telnet/SSH HTTP to/from 10.10.100.100 Email (SMTP, POP, IMAP, Exchange) Everything else (default-best effort) This list is a good representation of some real-world environments I've seen, and implementing it will illustrate how to mark different types of traffic in different ways. Determine Bandwidth Requirements To illustrate how to determine the bandwidth requirements for the various protocols, we'll use the sample network from the previous chapter, shown in Figure 30-1. Building A Building B Figure 30-1. Two-building network with a single T1 Low-la