Cabletron Systems SMARTSWITCH ROUTER 9032578-05 Manual de usuario descargar pdf (Pagina 312)

Chapter 20: Security Configuration Guide

286 SmartSwitch Router User Reference Manual

Layer-4 Bridging and Filtering

Layer-4 bridging is the SSR’s ability to use layer-3/4 information to perform filtering or

QoS during bridging. As described in “Layer-2 Security Filters” above, you can configure

ports to filter traffic using MAC addresses. Layer-4 bridging adds the ability to use IP

addresses, layer-4 protocol type, and port number to filter traffic in a bridged network.

Layer-4 bridging allows you to apply security filters on a “flat” network, where the client

and server may reside on the same subnet.

Note:

Ports that are included in a layer-4 bridging VLAN must reside on updated SSR

hardware. Please refer to Appendix A for details.

To illustrate this, the following diagram shows an SSR serving as a bridge for a consultant

host, file server, and an engineering host, all of which reside on a single subnet.

Figure 25. Sample VLAN for Layer-4 bridging

You may want to allow the consultant access to the file server for e-mail (SMTP) traffic,

but not for Web (HTTP) traffic and allow e-mail, Web, and FTP traffic between the

engineer and the file server. You can use Layer-4 bridging to set this up.

Setting up Layer-4 bridging consists of the following steps:

• Creating a port-based VLAN

• Placing the ports on the same VLAN

• Enabling Layer-4 Bridging on the VLAN

• Creating an ACL that specifies the selection criteria

• Applying an ACL to a port

et.1.1 et.1.2

Consultant File Server

SSR

1.1.1.1/24

1.1.1.2/24

Engineer

et.1.3

1.1.1.3/24

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Cabletron Systems SMARTSWITCH ROUTER 9032578-05 Manual de usuario Pagina 312