INTER-VLAN ROUTING

Question 1

What are the three inter-VLAN routing options: Illustrate them

Answer 1

Legacy Inter-VLAN routing - This is a legacy solution. It does not scale well.
Router-on-a-Stick - This is an acceptable solution for a small to medium-sized network.
Layer 3 switch using switched virtual interfaces (SVIs) - This is the most scalable solution for medium to large organizations

*See netacad for illustrations

Question 2

Describe Legacy inter-VLAN routing

Answer 2

In this method, multiple router interfaces are used, each connecting to a switch port in different VLANs. These interfaces are served as default gateways, which requires additional cabling when the network has to be expanded.

Hence, adding additional network cables and improving infrastructure is more expensive.

Question 3

Describe Router-on-a-stick

Answer 3

In this method, unlike the legacy routing, one physical interface port is used for routing the traffic between the network segments. The network administrator doesn’t need to create separate VLAN interfaces like fa0/1 to fa0/10.

Instead, all the interfaces from 1 to 10 are created with a single interface. This method is simple to implement and used for small to medium-sized networks.

Question 4

Describe Layer 3 switch using Switched Virtual Interface (SVI)

Answer 4

Currently, this method of inter-VLAN routing that uses layer 3/multilayer switch and Switched Virtual Interfaces (SVI) is the most preferred.

SVIs are created for VLANs exists on the switch which performs the same function for the VLANs as that of a router.

Layer 3 switches are expensive, which are primarily suitable for large organization networks.

Question 5

What are the advantages of Layer 3 switch using Switched Virtual Interface (SVI)

Answer 5

They are much faster than router-on-a-stick because everything is hardware switched and routed.
There is no need for external links from the switch to the router for routing.
They are not limited to one link because Layer 2 EtherChannels can be used as trunk links between the switches to increase bandwidth.
Latency is much lower because data does not need to leave the switch in order to be routed to a different network.
They more commonly deployed in a campus LAN than routers.

Question 6

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Question 7

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