The second problem we encountered was that the network interface and the Unibus on the 11/750 were both bottlenecks [GERB87, DEWI88]. While the bandwidth of the token ring itself was 80 megabits/second, the Unibus on the 11/750 (to which the network interface was attached) has a bandwidth of only 4 megabits/second. When pro- cessing a join query without a selection predicate on either of the input relations, the Unibus became a bottleneck because the transfer rate of pages from the disk was higher than the speed of the Unibus [DEWI88]. The network interface was a bottleneck because it could only buffer two incoming packets at.
