VRRP Concepts - Gateway Redundancy

In this session, we will learn about VRRP, gateway redundancy in the network. It's a feature that's usually used to redundancy two backbone switches.

 

It's not as easy as you think if you can do redundancy work on the switch, it's going to be at some level, so watch carefully.

 

 

1.  VRRP (Virtual Redundancy Routing Protocol)

 

 

: VRRP requires a Layer 3 switch or router that acts as a gateway to communicate with equipment with different network addresses on equipment that does not have routing capabilities, such as PCs or servers.

 

Operate more than one gateway in a network-dependent environment. VRRP is the protocol that automatically allows other devices to act as gateways when one gateway goes down.

 

VRRP operates between gateway devices, and the PC sets the virtual IP address set in the VRRP device as the gateway address. One of the VRRP devices acts as an active device, which handles packets destined for the gateway address.

 

A non-active VRRP device monitors the active device. If the active VRRP device goes down, the router that was in standby takes over the active device role and continues to act as a gateway.

 

 

The figure on the left shows the case where the Single Point of Failure service is disconnected when the only Gateway R1 connected to the external network is down.

 

As shown in the figure on the right, when R1 is down through gateway redundancy, it shows an auto-failover through R2. (To Avoid Single Point of Failure) No service disconnect VRRP is standard protocol.

 

 

 

 

2. Principles of VRRP Operation

 

 

 

 

Both devices determine Master and Backup based on priority values.

 

1) When VRRP is enabled, VRRP advertisement packets are exchanged between R1 and R2, and R1 with a higher priority value becomes the master.

 

2) The master sends a VRRP advertisement packet to Backup at a set advertisement-interval interval (usually 2 seconds) to notify that he is alive.

 

3) If R1 no longer sends VRRP packets, R2 recognizes that R1 has a problem after a certain period of time (Dead Timer).

 

4) R2 sends a VRRP advertisement packet and a GARP packet to indicate that it has become a master.

 

5) The backup appliance changes its role to Active because it has a higher priority than the Master appliance, and the Master appliance changes its role to Standby because it has a lower priority than the backup appliance.

 

- The above process changes the priority of each equipment and changes the role of each process.

 

 

 

* Virtual MAC

: Assign virtual MAC to IP received through virtual router

 

* Virtual IP

: Allocate virtual IP instead of Real IP. This IP becomes gateway

 

* advertisement Message

: Give me a message every second. Health check.

 

* advertisement Interval

: Advertisement message sent. Time not received => After this time, the equipment is recognized as down

 

* Priority Default Value 100 (High Value Master) Let's compare the standard protocols VRRP, HSRP used by Cisco, and VRRP-EX versions.

 

 

 

 

VRRP [ Virtual Redundancy Routing Protocol ]

 

: Default Gateway Redundancy Technology

 

- Each of the two equipment has one Real IP

- Two devices use one Virtual Mac

- Internal users use the default gateway with the master's Virtual Mac and Real IP

- In the event of a master equipment failure, the backup equipment's Real IP has the master's Real IP, and the Mac uses Virtual Mac.

 

 

 

 

HSRP [ Hot Standby Routing Protocol ]

: Default gateway redundancy technology (independent protocol used only on Cisco equipment)

 

- Both devices have Real IP and Real Mac on their respective interfaces.

- Both devices have Virtual IP and Virtual Mac for practical communication.

- Standby equipment uses Virtual IP, Mac in case of Active equipment failure

 

 

 

 

VRRP-EX [ Virtual Redundancy Routing Protocol – Extended ]

: Gateway Redundancy Protocols Used by Foundry Equipment

 

- VRRP의 Enhancement

- Both devices have Real IP and Real Mac on their respective interfaces.

- Both devices have Virtual IP and Virtual Mac for practical communication.

- In the event of an Active Equipment failure, the Standby Equipment uses Virtual IP, Mac Note that VRRP and HSRP in the field actually do not work well.

 

Although it is compatible with the same vendor, it is difficult to guarantee that redundancy between other vendors will work without having to try it yourself.

 

Even if you use a standard protocol in theory, it seems that there is always a difficulty in compatibility because each vendor has its own characteristics.

 

 

 

 

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