CHAPTER 2 Network Planning
Application Examples
MAKING VLAN CONNECTIONS
These switches support VLANs which can be used to organize any group of network nodes into separate broadcast domains. VLANs confine broadcast traffic to the originating group, and can eliminate broadcast storms in large networks. This provides a more secure and cleaner network environment.
VLANs can be based on untagged port groups, or traffic can be explicitly tagged to identify the VLAN group to which it belongs. Untagged VLANs can be used for small networks attached to a single switch. However, tagged VLANs should be used for larger networks, and all the VLANs assigned to the
These switches also support multiple spanning trees which allow VLAN groups to maintain a more stable path between all VLAN members. This can reduce the overall amount of protocol traffic crossing the network, and provide a shorter reconfiguration time if any link in the spanning tree fails.
At Layer 3, VLANs are used to create an IP interface, where one or more ports are assigned to the same IP segment. Traffic is automatically routed between different IP segments on the same switch, without any need to configure routing protocols.
Figure 10: Making VLAN Connections
R&D
VLAN | 1 |
| Tagge d |
| Ports |
|
|
|
|
| Unta gged Ports |
| |||
|
|
|
|
|
|
|
|
| VLAN |
|
| Fina nce |
|
|
|
| una ware | ||
|
|
|
|
|
| switch | |||
VLAN 2 |
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
| |
Testing |
|
|
|
|
|
|
| Marketing | |
|
|
|
|
|
|
|
| ||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| VLAN 3 |
|
|
|
|
|
| ||
|
|
|
|
|
|
|
|
| |
|
|
| VLAN 4 |
|
|
|
|
| |
Tagge d Port
VLAN aware switch
R& D
Finance
Testing
VLAN 1 VLAN 2
VLAN 3
NOTE: When connecting to a switch that does not support IEEE 802.1Q VLAN tags, use untagged ports.
– 37 –
