SmartSwitch Router User Reference Manual 369
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.
Features
Port /
Interface
Base Ingress Port/
Interface Egress Port/
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 —