Ip Routing Benefits; Routing Between Ip Subnets - Lenovo RackSwitch G8264 Application Manual

IP Routing Benefits

Routing Between IP Subnets

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G8264 Application Guide for ENOS 8.4
The switch uses a combination of configurable IP switch interfaces and IP routing
options. The switch IP routing capabilities provide the following benefits:
 Connects the server IP subnets to the rest of the backbone network.
Provides the ability to route IP traffic between multiple Virtual Local Area

Networks (VLANs) configured on the switch.
The physical layout of most corporate networks has evolved over time. Classic
hub/router topologies have given way to faster switched topologies, particularly
now that switches are increasingly intelligent. The G8264 is intelligent and fast
enough to perform routing functions at wire speed.
The combination of faster routing and switching in a single device allows you to
build versatile topologies that account for legacy configurations.
For example, consider a corporate campus that has migrated from a router‐centric
topology to a faster, more powerful, switch‐based topology. As is often the case, the
legacy of network growth and redesign has left the system with a mix of illogically
distributed subnets.
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), competition 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
switching performance. This eases the load on the router and saves the network
administrators from reconfiguring every end‐station with new IP addresses.