Telephony routing algorithm

• If endpoints are within same CO, directly connect

• If call is between COs in same LEC, use one-hop path between COs

• Otherwise send call to one of the cores

• Only major decision is at toll switch

  • one-hop or two-hop path to the destination toll switch [called “alternate path routing”]
  • (why don’t we need longer paths?)

• Essence of problem

  • which two-hop path to use if one-hop path is full ?

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