device can also support metering with a granularity of for example 64kb s having bucket sizes between 4 k and 512 k the device may also include counters based on packet number or bytes with those counters being in profile out profile or general purpose the device also allows for rate limiting or shaping the device includes ingress per port rate limiting where when the incoming bandwidth exceed a programmed threshold the port can either send a pause frame or drop packets the rate control is on a per port basis and support for egress per port rate limiting support may also be provided for rapid spanning tree protocol that may be deleted by the port and storm control on a per port basis the network device may also support link aggregation with for example 32 trunk groups with up to 8 ports in a trunk group trunking is also supported across modules and the load may be distributed based on source mac or ip address and or destination mac or ip address the packet buffer memory of the device may include external ddr sdram memory with a 128 data bit ddr sdram interface configured as 4 independent channels according to several embodiments each channel consists of 32 data bits and it own address and control signals the network device supports 32mb or 64 mb packet buffer memory size x16 and x32 ddr sdram memory and 166 mhz to 200 mhz clock ddr sdram memory for reliability and signal integrity there is support.