Explanation of Artwork

To clarify what the artwork represents, we now describe in a little more detail what each is capable of. This can be used as a reference when reading the chapters.

User

This is a computer of some sort . It is not specific to any operating system and can represent a single user or many thousands. It will typically have a TCP/IP address.

R (Router)

A Layer 3 router from any vendor running routing code of some sort. This can be any routing protocol and would typically have connectivity to the Internet.

Internet (Internet Cloud)

This symbol is used to represent a public or private network that could include an intranet or an extranet. Typically, routers, switches, and any other connectivity equipment, such as Frame Relay, ATM, and so forth, may be present here.

Layer 2 Switch

This represents any Layer 2 switch and could have many 10/100/1000 Ethernet ports. This switch is vendor independent and provides cost-effective connectivity.

Cache

While there are dedicated caching appliances, this could be caching software running on a PC platform.

Firewall

Again, this could be a dedicated firewall that is part of a large security deployment, or, could be a router with access control lists (ACLs) for security. Typically, it will be a Layer 3 device although Layer 2 (bridging) firewalls are not uncommon.

SSL (SSL Offload Device)

A device dedicated to handling SSL traffic.

CS (Content Switch)

This represents a Layer 4 to 7 switch. All of the functionality and features discussed in this book will be available within this device.

Server

This could be a single server or many hundreds of servers. These servers are not operating-system specific. If it can be connected to an IP-based network, it will typically be able to be load balanced.