Intel ZT8101 Priority, Filtering, Router Ports, Switch Management and Operating Concepts

Switch Management and Operating Concepts

Router Ports

Router ports allow multicast packets to be propagated throughout the network. Router ports can be either static or dynamic. Static router ports are special routes that you manually enter into the switch’s routing table. Usually it is a port that has a router attached to it, and the router has a connection to a WAN or to the Internet. Static router ports should be used sparingly, because when a network failure occurs, they do not change. However, they can reduce network traffic by eliminating the need for a routing protocol on a local network. For example, a local network, which has only one link to the network, is an ideal candidate for a static route. You can also use them to restrict the transmission path a datagram must follow, based on the datagram's destination address. You can add up to 32 static entries into the routing table.

Dynamic router ports are added by the switch. The switch monitors each port for UDP multicast packets and IGMP multicast group membership reports. When these packets are detected on a port, that port is dynamically assigned as a router port.

Priority

MAC address priority is a Layer 2 Class of Service. It allows certain frames, based on their MAC address, to receive special handling.

The frames can be prioritized based on where the MAC address appears:

•The source only

•The destination only

•Both the source and destination

Frames that match the criteria are given a priority tag. The switch supports only four hardware priority levels per egress port, so the eight levels are mapped to four as listed in the table below.

Priority in Frames	Priority Queue of ASIC
0 - 1	0
2 - 3	1
4 - 5	2
6 - 7	3

After an Ethernet frame has been prioritized, the switch forwards the Ethernet frame using the strict priority-based scheduling algorithm. With this policy, any packets residing in a higher priority queue are always transmitted first. Only when these queues are empty are packets in lower priority queues transmitted.

Filtering

A filtering database is used to segment the network and control communication between segments. It can also filter packets off the network for intrusion control. Static filtering entries can be made by MAC or IP addresses.

26 ZT8101 User’s Manual