Potamon fluviatile northeastern Greece. In mainland Greece, "P. fluviatile" is found in the drainages of the Axios, Thyamis, Aheron and Arachthos, Pineiós, Piros-Tethreas, Pamisos and Evrotas rivers. In the Ionian Islands, "P. fluviatile" is known to occur at only one site on Corfu, as well as on Kefalonia, Lefkada and Zakynthos. In the Aegean Islands, it is found on Skiathos and Skopelos (Sporades), on Euboea and Skyros, and at a single site on Andros in the Cyclades. "Potamon fluviatile" is at the western distributional limit of the genus "Potamon". Other species in the genus occur through Eastern Europe and the Middle East,
IS-IS of a single area. IS-IS also does not require Area 0 (Area Zero) to be the backbone area through which all inter-area traffic must pass. The logical view is that OSPF creates something of a spider web or star topology of many areas all attached directly to Area Zero and IS-IS by contrast creates a logical topology of a backbone of Level 2 routers with branches of Level 1–2 and Level 1 routers forming the individual areas. IS-IS also differs from OSPF in the methods by which it reliably floods topology and topology change information through the network. However, the