Consider a communications network G with a fixed bidirectional routing ϱ in which node and edge faults F might occur. The diameter D( R(G, ϱ) F of the surviving route graph could be one of the fault-tolerant measurements. This paper shows the following results for a K-connected graph G = ( V, E): (1) If |V| ⩾ 2 K 2, then there is a routing ϱ 1 such that if |F|< K , then D(R (G, ϱ 1) F )⩽3 . (2)If |V|⩾ K 2 and K ≠ 2 and 4, then there is a ϱ 2 such that if |F| < K , then D(R (G, ϱ 2) F ) ⩽5 .