The Cisco Catalyst 4500E Series offers four chassis options and eight supervisor engine options . It provides a common architecture that can scale up to 388 ports. The Cisco Catalyst WS-C4507R+E, WS-C4510R+E, WS-C4507R-E, and WS-C4510RE offer high availability by supporting 1+1 redundant supervisor engines with subsecond failover time and full-image In-Service Software Upgrades (ISSUs). Nonstop forwarding with Stateful Switchover (NSF/SSO) and ISSU help ensure continuous packet forwarding during supervisor engine switchover to help ensure high availability for collaboration applications and voice over IP (VoIP). Using the same line cards as the widely deployed Cisco Catalyst 4000 Series Switches and classic Cisco Catalyst 4500 Series Switches, the Cisco Catalyst 4500E Series furthers Cisco's commitment to affordable enterprise and branch scalability.