# High-Density Ethernet

The following modules support high-density Ethernet:

- GE-HDE line module and GE-8 I/O module combination
- ES2 4G LM and ES2-S1 10GE IOA module combination
- ES2 4G LM and ES2-S1 GE-8 IOA module combination

In the current release, you cannot configure port parameters for high-density Ethernet. Instead, JunosE Software contains a packet classifier that enables the module to intelligently drop certain packets when the module becomes oversubscribed. The packet classifier inspects each incoming packet to determine whether to classify it as control traffic. To enhance network stability, the packet classifier prioritizes control traffic over non-control traffic (that is, data). The packet classifier randomly drops non-control packets when the interface is oversubscribed.

When the I/O module or IOA is oversubscribed, the packet classifier prioritizes the following types of control traffic:

- PPP discovery or PPP session
- Address Resolution Protocol (ARP)
- 802.3ad (link aggregation)
- 802.3 Spanning Tree Protocol (STP)
- IPv4 and IPv6 DHCP server
- IPv4 and IPv6 DHCP host
- IPv6 Neighbor Discovery
- IPv4 virtual router alert
- IPv4 and IPv6 Internet Group Management Protocol (IGMP)
- IPv4 packets with a type of service (ToS) precedence value set to Internetwork Control (C0)
- IPv6 packets with a traffic class precedence value set to Internetwork Control (C0)