Installation guide

Important to Know Before Installation

Illustration 2.2 Correct Cable Types for Single Layer 2 Firewalls

For more information on cabling for IPS engines and Layer 2 Firewalls, see the McAfee NGFW

Reference Guide for IPS and Layer 2 Firewall Roles.

Speed And Duplex

Mismatched speed and duplex settings are a frequent source of networking problems. The

basic principle for speed and duplex settings is that network cards at both ends of each cable

must have identical settings. This principle also applies to the automatic negotiation setting: if

one end of the cable is set to autonegotiate, the other end must also be set to autonegotiate

and not to any fixed setting. Gigabit standards require interfaces to use autonegotiation. Fixed

settings are not allowed at gigabit speeds.

For Inline Interfaces, the settings must be identical on both links within each Inline Interface pair

(identical settings on all four interfaces) instead of just matching settings at both ends of each

cable (two + two interfaces). If one of the links has a lower maximum speed than the other link,

the higher-speed link must be set to use the lower speed.

Illustration 2.3 Speed/Duplex Settings

Switch

Host/Firewall

Crossover cable

Switch

Straight cable

Single Layer 2

Firewall

100/Full

Correct Incorrect

100/Full

1000/Full