Form factor:
- NIM-ES2-4: Single-wide NIM form factor

Dimensions (H x W x D):
- NIM-ES2-4: 0.8 x 3.1 x 4.8 in. (2.1 x 7.9 x 12.2 cm)

IEEE protocols
- Gigabit Ethernet: IEEE 802.3 and 10BASE-T
- Gigabit Ethernet: IEEE 802.3u, 100BASE-TX, and 1000BASE-TX
- IEEE 802.1d Spanning Tree Protocol
- IEEE 802.1p CoS for Traffic Prioritization
- IEEE 802.1q VLAN
- IEEE 802.1X Security
- IEEE 802.3x Full Duplex
- IEEE 802.3af Power over Gigabit Ethernet Standard

RFC
- RFC 2284, PPP Extensible Authentication Protocol (EAP)

Manageability
- SNMP and Telnet interface support delivers comprehensive in-band management, and a CLI management console provides detailed out-of-band management.
- An embedded RMON software agent supports four RMON groups (history, statistics, alarms, and events) for enhanced traffic management, monitoring, and analysis.
- A SPAN port can mirror traffic from one or many ports to another port for monitoring all eight RMON groups with an RMON probe or network analyzer.

Connectors and cabling
- 10BASE-T ports: RJ-45 connectors, two-pair Category 3, 4, or 5 unshielded twisted pair (UTP) cabling
- 100BASE-TX ports: RJ-45 connectors; two-pair Category 5 UTP cabling
- 1000BASE-TX ports: RJ-45 connectors; two-pair Category 5e and Category 6 UTP cabling

LED indicators
- Link status LED: One LED per port for indicating link status
- PoE LED: One LED per port system for PoE status indication

Power Requirements
- Internal power supply: Optional PoE system power supply available for all Cisco 4000 Series routers
- Internal redundant power supply: For the Cisco 4431 and 4451 routers only