Cabletron Systems 9032578-05 manual Summary, Weighted Random Early Detection Wred, Jumbo Frames

Appendix A: New Features Supported on Line Cards

Weighted Random Early Detection (WRED)

Weighted Random Early Detection (WRED) algorithms can alleviate traffic congestion. WRED allows you to set conditions and limits for the selective dropping of packets on input or output queues of specific ports before the queues become completely flooded.

The ports on which WRED are enabled must reside on T-series line cards.

Jumbo Frames

Jumbo frames (frames larger than the standard Ethernet frame size of 1518 bytes) can provide lower frame rates for applications that send very large amounts of data at high speeds. On the SSR, jumbo frames are configured at the port level by setting the maximum transmission unit (MTU) size.

The ports on which jumbo frames are configured must reside on PoS, ATM, or Gigabit Ethernet T-series line cards. If you are configuring an interface for jumbo frame transmission, note that the interface must include only ports on the aforementioned line cards. If the interface includes ports that do not support jumbo frames, then the interface MTU will be 1500 bytes. Packets switched in software will be limited to a size of 1500 bytes. However, the MTU for packets that are switched through the hardware and exit the aforementioned port types is determined by the individual port MTU.

Summary

The following table summarizes the hardware requirement on ingress and egress ports or interfaces for features that require the -AA or T-series line card.

	Port /
	Interface	Ingress Port/	Egress Port/
Features	Base	Interface	Interface
Network Address Translation (NAT)	Interface	AA/T-series	AA/T-series
Load Balancing (LSNAT)	Interface	AA/T-series	AA/T-series
Layer 4 Bridging	Port	AA/T-series	AA/T-series
Per-protocol VLAN	Port	AA/T-series	AA/T-series
Per-flow Rate Limiting	Interface	AA/T-series	—
ToS Rewrite	Interface	AA/T-series	—
ToS Rewrite (with L4 Bridging)	Port	AA/T-series	AA/T-series
Established Bit ACL	Interface	AA/T-series	—

SmartSwitch Router User Reference Manual 369