2.2.3 Edge-core-edge topology Edge-core-edge is the most scalable topology, it is used for installations where a core-edge  fabric made up of multislot director-class SAN switches is insufficient. This design is useful for  large, multiclustered system installations. Similar to a regular core-edge, the edge switches  can be of any size, and multiple ISLs must be installed per switch.  Figure 2-4 shows an edge-core-edge topology with two different edges, one of which is  exclusive for the FlashSystem and high-bandwidth servers. The other pair is exclusively for  servers. Edge-core-edge fabrics allow better isolation between tiers. For additional information, see  2.2.6, “Device placement” on page 19. Figure 2-4 Edge-core-edge topology Chapter 2. Storage area network  17