Case study: ATM ABR congestion control
if sender’s path “underloaded”:
- sender should use available bandwidth
if sender’s path congested:
- sender throttled to minimum guaranteed rate
RM (resource management) cells:
sent by sender, interspersed with data cells
bits in RM cell set by switches (“network-assisted”)
- NI bit: no increase in rate (mild congestion)
- CI bit: congestion indication
RM cells returned to sender by receiver, with bits intact