VRRP (Virtual Router Redundancy Protocol)

hi Andrew
Why have you used the same ip address for interface vlan A and B 192.168.1. 252?

Hello Daniel

You’re right, it seems that it was a typo. The IP addresses on VLAN B have 2 as the third octet. I’ve corrected the post so that it shows the right IP addresses.

Thanks for pointing that out!

Laz

Ok, went through this entire thread and didn’t find a single mention of IPv6 for VRRP. I know the original protocol did not support IPv6, but was wondering if there was an update for support. I’ve been using HSRP for most of my IPv4/v6 links, but am starting to move to more Arista gear and need to start thinking of protocols that support multiple vendors.

Any pointers to IPv6 support would be helpful.

Marcos

Hello Marcos

VRRPv3 supports the use of both IPv4 and IPv6 addresses. You must however ensure that the platform and IOS combination you are using support VRRPv3 in order to implement it. You can find out configuration information at the following Cisco documentation:

I hope this has been helpful!

Laz

Hi,
Is it possible to advertise a vrrp virtual IP over and IGP such as OSPF? Or is the only way to reach the VIP by setting static route to it?

Hello Hassan

First Hop Redundancy Protocols (FHRPs) are used to provide a redundant gateway to hosts. This means that FHRPs like VRRP and others should be implemented on subnets that contain end-user host devices. Typically, FHRPs are not used to connect to subnets that have routers that route traffic further downstream. As such, you should not need to advertise the IP addresses of the redundant gateways using an IGP.

Now having said that, if you still want to use an IGP with VRRP (or HSRP, or GLBP), keep the following rule of thumb in mind: Only the IP addresses of the physical interfaces are advertised. In other words, IGPs will not advertise the virtual IP address. However, keep in mind that VRRP allows you to have a virtual IP address that is the same as the real IP address on the interface of one of the redundant routers. This of course may cause problems in routing if that particular router goes down. The other router will adopt that IP address, but the IGP will attempt to reach the failed router, resulting in failed connectivity.

If you want to achieve load balancing in the core of your network, it is preferable to use the load balancing features of routing protocols rather than an FHRP.

I hope this has been helpful!

Laz

bonsoir monsieur Rene , dans ce cours vous faites la comparaison des protocoles HSRP et VRRP en mentionnant dans le tableau l’une des diiference qui est leur adresse de multidiffusion .:224.0.0.2 et 224.0.0.18 , ma préoccupation est de savoir comment un protocole peut avoir l’adresse de multidiffusion à quoi ça sert concretement à ces protocoles , puisque dans le cour de multidiffusion je pense avoir retenu que ce sont les routeurs qui utilisent les adresses pour diffuser les paquets et les hotes se servent aussi de ces adresses pour en faire la demande

Hello Berthol

In order to operate correctly, many protocols and features use multicast to fulfill their functions. For example, OSPF and EIGRP routers need to send out hello messages and updates to communicate with other OSPF and EIGRP routers and establish their neighbor adjacencies. When such routing protocols are enabled, they automatically become members of specific predefined multicast groups for this purpose.

In a similar manner, VRRP and HSRP devices must communicate with each other in order to establish their function. When VRRP or HSRP is configured on a device, it automatically becomes part of the multicast group corresponding to the reserved multicast address.

Multicast is a convenient way of employing such features because initially, the devices involved have no information about how to reach each other to communicate. If a specific multicast address is reserved for these purposes, then HSRP and VRRP devices will automatically find each other and create their initial communication to make the feature work correctly. In such cases, you don’t need to configure multicast at all, this is all preconfigured by the feature itself.

I hope this has been helpful!

Laz

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