RackSwitch G8000 Application Guide
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Chapter 8: Basic IP Routing BMD00041, November 2008
This is a situation that switching alone cannot cure. Instead, the router is flooded with cross-
subnet communication. This compromises efficiency in two ways:
Routers can be slower than switches. The cross-subnet side trip from the switch to the
router and back again adds two hops for the data, slowing throughput considerably.
Traffic to the router increases, increasing congestion.
Even if every end-station could be moved to better logical subnets (a daunting task), competi-
tion for access to common server pools on different subnets still burdens the routers.
This problem is solved by using switches with built-in IP routing capabilities. Cross-subnet
LAN traffic can now be routed within the switches with wire speed Layer 2 switching perfor-
mance. This not only eases the load on the router but saves the network administrators from
reconfiguring each and every end-station with new IP addresses.
