Port extender with local switching

A method implemented in a first port extender in a switching system that includes a controlling switch and a plurality of other port extenders, the method comprising:

• receiving packets via at least one local upstream port of the first port extender, the at least one upstream port being coupled to the controlling switch directly or via a second port extender among the plurality of other port extenders;
• receiving packets via a plurality of local downstream ports of the first port extender, including receiving a first packet via a first local downstream port that is coupled to a third port extender among the plurality of other port extenders;
• processing received packets with a packet processor of the first port extender that is incapable of processing one or more packet header types that the controlling switch is capable of processing;
• for packets received via the plurality of local downstream ports, searching a forwarding database that is populated with entries indicating associations between i) respective network addresses corresponding to devices coupled to local downstream ports, among the plurality of downstream ports, of the first port extender a) directly orb) via one or more other port extenders downstream from the first port extender, and ii) respective local downstream ports, among the plurality of downstream ports, of the first port extender;
• in response to receiving the first packet:
• determining an association between i) a network address in a header of the first packet and ii) a port of the third port extender at which the first packet was first received by the switching system, and
• storing in the forwarding database the association between i) the network address in the header of the first packet and ii) the port of the third port extender;
• in response to receiving a second packet i) via one of the local downstream ports among the plurality of downstream ports, and ii) having a destination network address in the forwarding database, forwarding the second packet to a different local downstream port, among the plurality of downstream ports, indicated by the forwarding database;
• and
• in response to receiving a third packet i) via one of the local downstream ports among the plurality of downstream ports, and ii) having a destination network address not in the forwarding database, forwarding the third packet to the at least one local upstream port.