Elements / Ethernet

EtherSpanTree

802.1d Ethernet spanning tree implementation

SYNOPSIS§

EtherSpanTree(ADDR, INPUT_SUPPRESSOR, OUTPUT_SUPPRESSOR, SWITCH)

Ports: any number of inputs, the same number of outputs
Processing: push

DESCRIPTION§

Implements the IEEE 802.1d spanning tree algorithm for Ethernet switches. Expects 802.1d control packets on its inputs and reacts by selectively suppressing forwarding on an associated EtherSwitch.

ADDR is the address of this Ethernet switch. SWITCH is the name of an EtherSwitch element that actually switches packets. INPUT_SUPPRESSOR and OUTPUT_SUPPRESSOR are two Suppressor elements; they should be placed upstream and downstream of the SWITCH. The EtherSpanTree, Suppressor, and EtherSwitch elements should all have the same numbers of inputs and outputs, equal to the number of ports in the switch.

EXAMPLES§

  from_port0, from_port1 :: FromDevice...;
  to_port0, to_port1 :: ToDevice...;

  span_tree :: EtherSpanTree(00-1f-29-4d-f8-31, in_supp, out_supp, switch);
  switch :: EtherSwitch;
  in_supp, out_supp :: Suppressor;

  from_port0 -> c0 :: Classifier(14/4242, -); // ethertype 802.1d, others
  from_port1 -> c1 :: Classifier(14/4242, -);

  q0 :: Queue -> to_port0;
  q1 :: Queue -> to_port1;

  c0 [0] -> [0] span_tree [0] -> q0;
  c1 [0] -> [1] span_tree [1] -> q1;

  c0 [1] -> [0] in_supp [0] -> [0] switch [0] -> [0] out_supp [0] -> q0;
  c1 [1] -> [1] in_supp [1] -> [1] switch [1] -> [1] out_supp [1] -> q1;

SEE ALSO§

EtherSwitch, Suppressor

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