This is an estimate of the round trip delay of the network
pipe used for the B-D product computation, which lets us
derive the TCP receive window to advertise.
The cfmFcipEntityExtTcpMaxBW,cfmFcipEntityExtTcpMinAvailBW,
cfmFcipEntityExtTcpRndTrpTimeEst must be set in the same
SNMP set request. SET operation would fail if this object
is set individually.