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8 votes
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Why is a virtual MAC address needed in FHRP protocols?

The reason for using a virtual MAC address instead of each router's own MAC address, is that in case of a failover, you don't want to have to learn the new MAC address for the virtual IP address on ...
Teun Vink's user avatar
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6 votes
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HSRP change priority didn't failover

You forgot to use the standby 5 preempt command. It is also a good idea to set a preempt delay. Hot Standby Router Protocol (HSRP): Frequently Asked Questions: Q. Which HSRP router requires that I ...
Ron Maupin's user avatar
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6 votes
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Cisco HSRP CAM vs ARP timeout

What the ISP means is that as they make changes, you may lose connectivity for a time because the ARP table entries your router has with them will not match the changes it is making. If you reduce the ...
Ron Maupin's user avatar
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5 votes
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How exactly does a router get elected as an Active router in HSRP?

Cisco has many documents to explain such things. For example, Hot Standby Router Protocol (HSRP): Frequently Asked Questions: Q. If there is no priority configured for a standby group, what ...
Ron Maupin's user avatar
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3 votes

HSRP limitations on Catalyst 3560

An HSRP group on an interface is an instance. Each layer-3 interface could have an HSRP group 1, but each is a different instance, and, indeed, are actually different HSRP groups, despite having the ...
Ron Maupin's user avatar
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3 votes

What is VRRP used for?

VRRP is used to create a virtual router that can be made redundant by using two routers in a cluster. One router is active, the other is in standby. When the active router fails, the virtual router's ...
Zac67's user avatar
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3 votes
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What is VRRP used for?

VRRP, and other FHRPs such as HSRP, allow you to have a default gateway configured on your hosts that does not really exist. One router will take over the virtual router IP and MAC addresses, and if ...
Ron Maupin's user avatar
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3 votes
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VRRP vs HSRP for load sharing

FHRPs, like VRRP, and HSRP, don't load balance anything; that is not their purpose. The purpose of an FHRP is to give a virtual gateway, which can fail to a different physical router in the case of a ...
Ron Maupin's user avatar
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2 votes

What are the differences between VRRP and HSRP?

HSRP : 1) CISCO Proprietary 2) RFC 2281 3) Multicast group Ip: 224.0.0.2 V1 224.0.0.102 V2 4) Port No. UDP 1985 5) PREEMPT: By default disabled 6) Virtual Mac address: 0000.0c07.acxx ...
Kashyap Mehta's user avatar
2 votes
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Best way to setup VRRP if a router fails

One thing I noticed is that you are not tracking the links to the firewall, and you have no way configured for VRRP to fail over to the other switch if a link goes down. You will fail over if the ...
Ron Maupin's user avatar
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2 votes

Why is a virtual MAC address needed in FHRP protocols?

In RFC 5798 which defines the operations of VRRP, you will find in section 7.3 the following: (emphasis mine) 7.3. Virtual Router MAC Address The virtual router MAC address associated with a virtual ...
JFL's user avatar
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2 votes
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Can a router be part of multiple HSRP groups?

Yes, of course that is not only possible, but it is usually the case. Each VLAN will have at least one (possibly more) HSRP groups, even on the same interface. It used to be a common practice to set ...
Ron Maupin's user avatar
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2 votes
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hsrp on both side of router

in this topology, i should configure a HSRP group on interface 0/0/1(192.168.1.0 network) of router7 and router8, and configure another HSRP group on interface 0/0/0(172.24.0.0 network) of router7 ...
Ron Maupin's user avatar
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2 votes
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Does VRRP or HSRP work with 2 different upstream ISPs?

An FRHP (First Hop Redundancy Protocol), like HSRP and VRRP, will present virtual IP and MAC addresses to the LAN, and the LAN hosts can be configured to use the virtual IP address for the LAN gateway....
Ron Maupin's user avatar
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1 vote
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HSRP limitations on Catalyst 3560

Well I found an exact answer with documentation to match. The answer is 32. HSRP can be configured on 32 interfaces. (Documentation to provide an exact answer was what I had asked for, not various ...
Shōgun8's user avatar
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1 vote
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VRRP or Carp in Cisco 1900 Series

Yes, Cisco supports VRRP. Cisco maintains many documents regarding this, e.g. First Hop Redundancy Protocols Configuration Guide, Cisco IOS Release 15M&T: Enabling VRRP SUMMARY STEPS ...
Ron Maupin's user avatar
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1 vote
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Possible reasons for both VRRP and HSRP on same router

Having both HSRP and VRRP on a router is fine, as long as they are configured on different interfaces, which seems to be the case. There are probably several things wrong with the way this is ...
Ron Maupin's user avatar
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1 vote

HSRP Issue Both sides are active ( Layer 3 4300 X serires)

Your two devices cannot communicate over that VLAN, so they cannot exchange HSRP messages on that VLAN. Each comes up thinking it is the active router. One will remain the active router, and one will ...
Ron Maupin's user avatar
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1 vote
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How to setup VRRP with two routers and a single uplink (Internet connection)

You can use VRRP, assuming your routers support it, but it requires at least two or three IP addresses in the same network. You need an address for each of the routers, and one address for the virtual ...
Ron Maupin's user avatar
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