SVI Inter-VLAN Routing and Configuration
Overview
The architectures mentioned to date represent the SVI inter-VLAN routing architectures. the main issue with these
architectures is performance—if gigabit speed routing is needed between VLANs, very high performance and
expensive routers are needed. a brand new kind of SVI inter-VLAN routing on the LAN has emerged in recent years
referred to as Layer three change. With a Layer three switch, the historically separated Layer a pair of and Layer three
functions are combined into one device, eliminating the bottleneck related to the cable between a router and switch by
substitution the cable with a high-speed backplane association. Layer three switches conjointly generally perform
routing in specially designed hardware electronic equipment instead of code, exploitation specialised hardware which
will perform routing functions at high speed. this implies that the performance of Layer three switches is far on top of
traditional router-on-a-stick architectures. for instance, if you use a Cisco 3640 series router within the router-on-a-stick
design, you’ll be able to come through routing speeds of up to 40,000 packets per second. If you compare this with a
Cisco Catalyst 3550-24-EMI Layer 3 switch, that is truly cheaper than a Cisco 3640 router, you’ll be able to route
packets at up to 6.6 million packets per second. this is often clearly quite an distinction and highlights the restrictions of
exploitation router-on-a-stick architectures for SVI inter-VLAN routing on the LAN. Of course, the Cisco 3640 router still
encompasses a place within the network; it supports a large form of numerous media, as well as serial and ATM
connections for WAN connectivity; conjointly supports advanced options like firewalling, encryption, so on—all of that
don’t seem to be supported on Cisco Catalyst switches.
The Layer three switch uses application-specific integrated circuits (ASICs), that are hardware chips which will route
traffic at terribly high speeds. These ASICs are put in on the change engine of a Layer three switch, that traditionally
switches frames at Layer 2. The ASICs enable the change engine to conjointly switch frames that contain packets sent
between completely different VLANs. every ASIC is programmed with the data needed to route traffic from one VLAN
to a different, while not having to pass the traffic through the CPU of the routing engine. This info includes the egress
port, egress VLAN, and new destination mackintosh address that ought to be written for the frame that’s sent. Some
kind of route cache is often wont to store such info, with the ASIC looking the cache for routing info for the destination
IP address of packets as they’re received. however this info is programmed into the route cache depends on the Layer
three switch design used; but, the tip result’s basically identical.
SVI Inter-VLAN Routing Topology
Click here to download topology of SVI Inter-VLAN Routing.pkt
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