266 SAN Multiprotocol Routing: An Introduction and Implementation
8.4 Managing scalability with IVR
It is also possible to use VSAN and IVR to prevent fabrics from growing too large
because you add more ports on a modular basis. Although modern switches
typically include ways to limit registered state change notifications (RSCNs),
such as zone-limited RSCNs, some architects prefer to create smaller fabrics as
a way to improve high availability. This is not necessarily a good idea because it
introduces additional complexity. If you think about an Ethernet network, typically
you do not want to introduce multiple routers into your core network. The same
applies to VSAN and IVR. The guideline is to
resist the urge to route.
You can use VSAN and IVR to manage the growth of your network and to limit
the impact of a misconfiguration in a network that is subject to regular change. As
you add additional switch groups, you can isolate them, as shown in Figure 8-7.
Figure 8-7 Using VSAN and IVR to manage scalability