Virtual Router vs. Physical Router: Key Differences Explained

This article compares virtual routers and physical routers, highlighting their distinct features and functionalities. We’ll explore how the Virtual Router Redundancy Protocol (VRRP) plays a crucial role in virtual router setups.

Understanding Virtual Routers (VRRP Routers)

A virtual router, also known as a VRRP router, is essentially a physical router enhanced with the VRRP protocol.

Virtual Router

VRRP’s primary function is to ensure uninterrupted routing services. It does this by allowing a backup router to seamlessly take over the routing responsibilities of a master router if the master fails.

Imagine a scenario where Router-1 is the master router connected to Host-1. If Router-1 goes down, Host-1 would normally lose its internet connection. However, with VRRP in place, Router-2 (the backup router) automatically steps in and assumes Router-1’s role, maintaining Host-1’s connection without any service disruption.

VRRP is defined in RFC 2338 and RFC 5798. Key characteristics of a virtual router include:

• VRID (Virtual Router Identifier): Uniquely identifies the virtual router.
• IP Addresses: A set of IP addresses associated with the virtual router.
• MAC Address: A MAC address, just like a regular physical router.

VRRP packets include a “priority” field. This field, ranging from 0 to 255, determines the router’s priority in the virtual router group. A higher priority value signifies a greater chance of becoming the master router. Another field “Authentication Type” which takes any one of the following three values {0,1,2}.

• 0- No Authentication
• 1- Simple Text Password
• 2- IP Authentication Header

A virtual router operates in three states:

• Initialize: The initial state when the router starts.
• Master: The router actively forwarding packets. Master router take 255 as priority value
• Backup: The router monitoring the master and ready to take over. Backup router take 0 as priority value

For a deeper dive into how VRRP works, further resources should be consulted.

Physical Routers (IP Routers)

A physical router, or IP router, is a standard router without the VRRP functionality.

Physical Router

It relies on routing tables and destination IP addresses within IP headers to forward packets. These are also sometimes referred to as “logical routers.”

Consider the same scenario as before, but this time with Router-1 and Router-2 as simple physical routers. If Router-1 fails, Host-1’s connection to the internet will break until someone manually updates the routing table on Router-2. This is a significant difference from the automatic failover provided by a virtual router.

Router vs. Switch

Figure-2 illustrates a typical Wi-Fi router that provides internet connectivity to multiple devices like tablets, smartphones, laptops, and desktop PCs. These Wi-Fi routers work in conjunction with a modem, which establishes the connection to the Internet Service Provider (ISP). The router and modem are typically connected. Virtual Wi-Fi routers, which combine the functionality of a virtual router with Wi-Fi capabilities, are also available.

Key Differences Summarized

Here’s a table summarizing the core differences: