Cisco IPS-4255-K9 Installation Guide - Page 99

Chapter 4 Installing the IPS 4270-20 Front and Back Panel Features Hardware Bypass and Link Changes and Drops Properly configuring and deploying hardware bypass protects against complete link failure if the IPS appliance experiences a power loss, critical hardware failure, or is rebooted; however, a link status change still occurs when hardware bypass engages (and again when it disengages). During engagement, the interface card disconnects both physical connections from itself and bridges them together. The interfaces of the connected devices can then negotiate the link and traffic forwarding can resume. Once the appliance is back online, hardware bypass disengages and the interface card interrupts the bypass and reconnects the links back to itself. The interface card then negotiates both links and traffic resumes. There is no built-in way to completely avoid link status changes and drops. However, you can greatly reduce the interruption time (in some cases to sub-second times) by doing the following: • Make sure you use CAT 5e/6-certified cabling for all connections. • Make sure the interfaces of the connected devices are configured to match the interfaces of the appliance for speed/duplex negotiation (auto/auto). • Enable portfast on connected switchports to reduce spanning-tree forwarding delays. Front and Back Panel Features This section describes the IPS 4270-20 front and back panel features and indicators. Figure 4-5 shows the front view of the IPS 4270-20. Figure 4-5 IPS 4270-20 Front View Switches/Indicators 1 2 3 4 5 6 7 8 Cisco IPS 4270 SERIES Intrusion Prevention Sensor UID SYSTEPMWR SMTGAMTUTMS0GMT 1 250082 OL-18504-01 Cisco Intrusion Prevention System Appliance and Module Installation Guide for IPS 7.0 4-7