Networking Reference
In-Depth Information
default port of 80. When the packet reaches the destination computer, the logical port identifies the service
or application that will process the data.
Chapters 3 and 4 covered logical ports. These are numbers embedded in data packets.
Identifying the Number and Type of Ports
The number of ports on a switch or hub varies according to the physical size of the device. Hubs are less
expensive than switches and commonly have between 4 and 24 ports. This is usually enough for a small
office/home office (SOHO) network. If selecting a device for a small business with 8 or 10 users, a 24-port
device may be a reasonable investment, allowing for future growth.
Switches typically have between 8 to 64 ports. You can purchase switches in two separate designs:
Form Factor Switch This has a set number of ports built into the switch, and the number of ports can't
be changed. Form factor switches can have any number of ports, but 48 is the maximum for most form
factor switches. These switches are great where simplicity is required.
Modular Switch A modular switch starts with few to zero ports and can expand to hundreds of ports.
You can then add plug-in modules to add ports. This is similar to a computer that can accept additional
memory modules. For example, the computer may start with 1 GB RAM, but you can add RAM when
your needs change. Similarly, you can buy a modular switch with a module that includes eight ports but
then add modules to increase the number of available ports.
You can add different types of modules to a modular switch. This includes modules for typical
RJ-45 ports, wireless services, video services, and more.
Selecting a switch design is based on several factors. For example, you will want to ensure you have
enough ports for your immediate needs while also considering future growth requirements. Most modular
switches require programming, which adds administrative overhead, while many form factor switches work
right out of the box.
Identifying Ports in Drawings
When switches are included in network drawings or connection maps, the ports are usually labeled. This
allows technicians to identify what port goes to what system. Switch ports are commonly labeled with E, F,
or Gi followed by a number. For example, the following conventions are common:
E The first 10 Mbps port is labeled as E0. This indicates Ethernet port 0. Some manufacturers represent
the first Ethernet port on a modular switch as E0/0, which represents the first port on the first module.
F The first 100 Mbps port is typically labeled as F0 or F0/0, a Fast Ethernet port. Compare this to the
second port on the first module, which is labeled as F0/1. Fast Ethernet ports can also be labeled as Fa
instead of just F.
Gi The first 1000 Mbps port is labeled as Gi0/0, a gigabit port. Similarly, the first port on the second
module is Gi1/0.
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