SmartSwitch Router User Reference Manual 369Appendix A: New Features Supported on Line CardsWeighted 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 oninput 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 FramesJumbo frames (frames larger than the standard Ethernet frame size of 1518 bytes) canprovide lower frame rates for applications that send very large amounts of data at highspeeds. On the SSR, jumbo frames are configured at the port level by setting the maximumtransmission unit (MTU) size.The ports on which jumbo frames are configured must reside on PoS, ATM, or GigabitEthernet T-series line cards. If you are configuring an interface for jumbo frametransmission, note that the interface must include only ports on the aforementioned linecards. If the interface includes ports that do not support jumbo frames, then the interfaceMTU will be 1500 bytes. Packets switched in software will be limited to a size of 1500bytes. However, the MTU for packets that are switched through the hardware and exit theaforementioned port types is determined by the individual port MTU.SummaryThe following table summarizes the hardware requirement on ingress and egress ports orinterfaces for features that require the -AA or T-series line card.FeaturesPort /InterfaceBaseIngress Port/InterfaceEgress Port/InterfaceNetwork Address Translation (NAT) Interface AA/T-series AA/T-seriesLoad Balancing (LSNAT) Interface AA/T-series AA/T-seriesLayer 4 Bridging Port AA/T-series AA/T-seriesPer-protocol VLAN Port AA/T-series AA/T-seriesPer-flow Rate Limiting Interface AA/T-series —ToS Rewrite Interface AA/T-series —ToS Rewrite (with L4 Bridging) Port AA/T-series AA/T-seriesEstablished Bit ACL Interface AA/T-series —
