The following resources may be consulted for further information. Resources are listed here as examples only, and no endorsement of any company or software package is implied.
The formal IEEE standards are a moving target: old versions of the standards are periodically updated, and new standards are often being developed.
- The specifications for basic Ethernet bridges are found in the 802.1D standard for MAC bridges
- Published IEEE 802.1 “Bridging and Management” standards
- Active and archived projects for the IEEE 802.1 working group
- The Open Systems Interconnection (OSI) model describes the set of tasks involved in computer communication as a set of abstraction layers
- Cisco IOS Configuration Guide: “Configuring STP and MST”
Cisco white paper: “Understanding Multiple Spanning Tree Protocol (802.1s)”
- This white paper documents the differences between Cisco’s version of spanning tree, known as “Per-VLAN Spanning Tree Plus (PVST+),” and the most recent variation of spanning tree developed by the IEEE, known as “Multiple Spanning Tree.”
Interconnections: Bridges, Routers, Switches and Internetworking Protocols (2nd Edition), by Radia Perlman. Addison-Wesley. 1999.
- An expert’s insights into network protocols and how networks function, by the developer of the spanning tree protocol. This book reveals how a protocol designer thinks about networks and protocols.
The All-New Switch Book: The Complete Guide to LAN Switching Technology, by Rich Seifert and James Edwards. Wiley Publishing Inc. 2008.
- An exhaustive treatment of LAN switching, from the basics up to the most advanced topics.
Routing without tears; Bridging without danger
- The inventor of the spanning tree protocol, Radia Perlman, gave this Google Tech Talk in 2008. In the first half of the presentation, she describes how the spanning tree protocol came about and how basic spanning tree functions. The second half of the talk is about a new bridging protocol that she developed called TRILL.
- Ixia is a vendor of performance analysis tools whose Web site provides information on how performance is measured. These tools are typically used in large corporate and enterprise networks to monitor and analyze network performance.
- Some tutorials on switch latency specifications and how they are measured, from Cisco and Juniper.
There are many network management packages, and a number of vendors provide some level of network and switch management software for their products. It is impossible to list all of the network management systems, or even a representative sample in these resources.
The packages listed here are examples of network management packages that are not tied to a single vendor or equipment type.
- InterMapper discovers and documents Layer 2 and Layer 3 networks, and includes Netflow analysis.
- NetBrain network documentation and testing software has the ability to discover and diagram a Layer 2 network:
- SolarWinds provides a suite of tools that monitor network performance in switches. These tools also use the Simple Network Management Protocol (SNMP) to provide access to interface counters and other switch information.
Network design is a large topic, and there are multiple network types that each have different design requirements. Enterprise and campus networks are designed differently than data center networks. Wide area and branch office networks also have their own special requirements. In this section we provide links with information on campus and enterprise network design.
- Networking vendor Cisco Systems makes available a set of documents covering “validated designs,” which include networking designs for a wide range of network environments. While they feature Cisco equipment, these guides contain a lot of useful information on the topics described.
- One of the design guides that goes into detail on network design is the Campus Network for High Availability Design Guide.
All network designs have failure modes. For example, Layer 2 networks are vulnerable to traffic loop failures when spanning tree stops working, or when two ports on a switch with no STP support are connected together. (This happens more often than you might expect. For some reason, people like to play with Ethernet cables.) This failure mode is detailed in these two resources describing the collapse of a large hospital network:
- This article in CIO magazine documents the failure of a large Layer 2 network design at a major Boston hospital, which forced the staff to revert to paper-based operation while the network was repaired. It’s rare to find a useful description of a network failure. Many sites do not publish reports on failures or investigate root causes, and the lack of reports on network failure modes makes this report especially valuable.
- A blog posting entitled The CareGroup Network Outage provides more details on the Layer 2 network failure and “lessons learned.”
There is a large, worldwide market for Ethernet switches, with many vendors. Each vendor has a product line aimed at a given market or set of markets.
It would be a major task to provide a comprehensive buyer’s guide to the Ethernet switch market. Instead, in these resources, we will provide just a few examples, which should not be taken as endorsements of the equipment or the companies.
Switches for the general consumer, and small and medium business:
Campus, enterprise, data center, and service provider switches:
- Cisco white paper on PoE and their vendor-specific extensions
- The Cisco guide to troubleshooting PoE contains useful details on PoE design and operation
- The Wikipedia entry on PoE provides information on PoE operation