Lab 27: DLSw TCP, LLC2, Promiscuous, Dynamic, and Backup Peer Configuration-Part I

Chapter 13. Configuring Bridging and Data Link Switching Plus

Most of the early protocols were designed without explicit network addresses. For that reason, the protocol does not have the same concept of traditional Layer 3 that we have grown to love. Protocols without explicit network layer addresses, by definition, are called nonroutable or bridged protocols. Some examples of common bridged protocols are IBM Systems Network Architecture (SNA), NetBEUI, NetBIOS, and DEC LAT.

The most commonly used bridged protocols today are SNA and NetBEUI. IBM's SNA is found in many large data centers and is perhaps the most common bridged protocol that you will encounter in the field. With the advent of Windows 9 x and Microsoft Networking, NetBEUI started to creep across many networks as well.

Along with SNA, NetBEUI, and other nonroutable protocols comes the necessary evil of transporting them across multiple LAN segments and WAN segments. We call this a necessary evil because bridged traffic is extremely broadcast- intensive . Enabling bridging across your network can severely impact the performance of your network. For this reason, when you deploy any bridging on your network, try to control it or limit the segments of the network that it has to cross.

This chapter focuses on ways to transport nonroutable protocols by using the following methods :

• Transparent bridging

• Integrated routing and bridging

• Source-route bridging (SRB)

• Remote source-route bridging (RSRB)

• Data link switching (DLSw)