D-Link DGS-1250 User Manual - Page 226

DGS-1250 Series Gigabit Ethernet Smart Managed Switch Web UI Reference Guide If the CPU load rises above the rising threshold value, the Safeguard Engine function will be activated and the Switch will enter the exhausted mode. In the exhausted mode, the Switch will limit the bandwidth available for ARP and broadcast IP packets. If the CPU load falls below the falling threshold value, the Safeguard Engine will be deactivated and the Switch will exit the exhausted mode and enter the normal mode. Packets that are destined to the CPU can be classified into three groups. These groups, otherwise known as subinterfaces, are logical interfaces that the CPU will use to identify certain types of traffic. The three groups are Protocol, Manage, and Route. Generally, the Protocol group should receive the highest priority when the Switch's CPU processes received packets and the Route group should receive the lowest priority as the Switch's CPU usually does get involved in the processing of routing packets. In the Protocol group, packets are protocol control packets identified by the router. In the Manage group, packets are destined to any router or system network management interface by means of interactive access protocols, like Telnet and SSH. In the Route group, packets are identified as traversing routing packets that is generally processed by the router CPU. In the following table a list of supported protocols are displayed with their respective sub-interfaces (groups): Protocol Name 802.1X ARP DHCP DNS ICMPv4 ICMPv6Neighbor ICMPv6-Other Sub-interface (Group) Protocol Protocol Protocol Protocol Protocol Protocol Protocol IGMP LACP SNMP SSH STP Telnet TFTP Web Protocol Protocol Manage Manage Protocol Manage Manage Manage Description Port-based Network Access Control Address resolution Protocol Dynamic Host Configuration Protocol Domain Name System Internet Control Message Protocol IPv6 Internet Control Message Protocol Neighbor Discovery Protocol (NS/NA/RS/RA) IPv6 Internet Control Message Protocol except Neighbor Discovery Protocol (NS/NA/RS/RA) Internet Group Management Protocol Link Aggregation Control Protocol Simple Network Management Protocol Secure Shell Spanning Tree Protocol Telnet Trivial File Transfer Protocol Hypertext Transfer Protocol (HTTP) and Hypertext Transfer Protocol Secure (HTTPS) A customized rate limit (in packets per second) can be assigned to the Safeguard Engine's sub-interfaces as a whole or to individual protocols specified by the user in the management interface. Be careful when customizing the rate limit for individual protocols, using this function, as improper rate limits can cause the Switch to process packets abnormally. NOTE: When Safeguard Engine is enabled, the Switch will allot bandwidth to various traffic flows (ARP, IP) using the FFP (Fast Filter Processor) metering table to control the CPU utilization and limit traffic. This may limit the speed of routing traffic over the network. 217