Chapter 5: Key Protocols and Interfaces
Figure 34 on page 89 shows an example network that uses VLANs. In this example network, the physical LAN consists of a switch, two servers, and five clients. The LAN is logically organized into three different VLANs, each representing a different IP subnet. The features of this network are described in Table 7.
| Table 7. Example VLAN Network Topology | |
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Component |
| Description |
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VLAN #1 |
| An IP subnet consisting of the Main Server, PC #3, |
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| and PC #5. This subnet represents an engineering |
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| group. |
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VLAN #2 |
| Includes the Main Server, PCs #1 and #2 via shared |
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| media segment, and PC #5. This VLAN is a software |
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| development group. |
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VLAN #3 |
| Includes the Main Server, the Accounting Server and |
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| PC #4. This VLAN is an accounting group. |
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Main Server |
| A |
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| of the VLANs and IP subnets. The Main Server has an |
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| Allied Telesyn adapter installed. All three IP subnets |
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| are accessed via the single physical adapter |
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| interface. The server is attached to one of the switch |
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| ports, which is configured for VLANs #1, #2, and #3. |
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| Both the adapter and the connected switch port have |
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| tagging turned on. Because of the tagging VLAN |
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| capabilities of both devices, the server is able to |
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| communicate on all three IP subnets in this network, |
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| but continues to maintain broadcast separation |
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| between all of them. |
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Accounting |
| Available to VLAN #3 only. The Accounting Server is |
Server |
| isolated from all traffic on VLANs #1 and #2. The |
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| switch port connected to the server has tagging |
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| turned off. |
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PCs #1 and |
| Attached to a shared media hub that is then |
#2 |
| connected to the switch. PCs #1 and #2 belong to |
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| VLAN #2 only, and are logically in the same IP subnet |
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| as the Main Server and PC #5. The switch port |
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| connected to this segment has tagging turned off. |
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PC #3 |
| A member of VLAN #1, PC #3 can communicate only |
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| with the Main Server and PC #5. Tagging is not |
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| enabled on PC #3’s switch port. |
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PC #4 |
| A member of VLAN #3, PC #4 can only communicate |
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| with the servers. Tagging is not enabled on PC #4’s |
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| switch port. |
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