HSRP Vs VRRP Vs GLBP

 

Routing Protocols gives redundancy at layer 3

Redundancy between 2 switches, you connect 2 or more links between them.

Similarly to allow redundancy for your clients, you might want to connect 2 routers as the gateway to exit from the network.

FHRP  First Hop Redundancy Protocol

Gives redundancy at First Hop level gives redundancy at the gateway level

On PC I can configure only one IP address as default gateway. If that device (router) goes down then I would need to configure manually on my PCs the new default gateway.

So from the perspective of PC needs --> First Hop Redundancy

FHRP technology allows the 2 routers to share a single IP address. Or we can say a shared ip address between the 2 routers which is called as the VIP – Virtual IP .where you have the rights to prefer a specific router as forwarding router and another routers as Backup router.

Along with VIP the routers will also share mac address.

Forwarding router is the router which will be answering for the VIP and will forward the traffic .

FHRP establish the relationship between the 2 routers, hellos are exchanges between those routers and incase the forwarding/active/master router goes down then the standby router will become active and will now be answering for the VIP and will forward traffic for the clients.

We have the rights which router to be preferred as forwarding/active/master and backup/standby by manipulating the priority values.

Remember FHRP is the technology it is not the actual implementation.

There are 3 main FHRP Implementations HSRP VRRP AND GLBP

Protocol Features	HSRP - Hot Standby Protocol	VRRP - Virtual Redudancy Protocol	GLBP - Gateway Load Balancing Protocol
Scope	Cisco Proprietary	IEEE standard	Cisco proprietary
Standard	RFC2281	RFC3768	none
OSI Layer	Layer-3	Layer-3	Layer-2
Load Balancing	No	No	Yes
Multicast Group IP address	224.0.0.2 in version 1   224.0.0.102 in version 2	224.0.0.18	224.0.0.102
Transport Port Number	UDP 1985	UDP 112	UDP 3222
Timers	Hello – 3 sec	Advertisement – 1 sec	Hello – 3sec
	Hold – 10 sec	Master down time = 3*Advertisement Time + Skew TimeSkew Time = (256- Priority)/256	Hold – 10sec
Election	Active Router:1.Highest Priority2. Highest IP address (Tiebreaker)	Master Router: (*)	Active Virtual Gateway:
		1-Highest Priority	1-Highest Priority
		2-Highest IP (Tiebreaker)	2-Highest IP (Tiebreaker)
Router Role	One Active Router, One Standby Router , One or more listening Router/s	– One Active Router- One or  More Backup Routers	One AVG (Active Virtual Gateway)- up to 4 AVF  Routers on the group  (Active Virtual Forwarder) passing traffic. - up to 1024 virtual Routers (GLBP groups)  per physical interface.
Preempt	If Active Router(Highest Priority) is down and up again, Preempt should be configured to become a Active Router again	By default Preempt is ON in VRRP,  If Active Router is down and up again, It will automatically become a MasterRouter	If Active Router(Highest Priority) is down  and up again, Preempt should be configured  to become a Active Router again.
Group Virtual Mac Address	0000.0c07.acxx	0000.5e00.01xx	0007.b4xx.xxxx
IPv6 support	Yes	No	Yes

 

Mnemonics for Networking

Mnemonics is derived from a Greek word “mnemonikós”, which means Mind, this learning technique is used for information intention.  Mnemonics allows us to easily transform unrelated information into a form which is easily understood by our brain than its original form. In simple words, it helps us to remember unrelated information easily.

Here is a technique to remember a list of unrelated items in order using Mnemonics:

1)  7 layers of OSI model:

Please Do Not Tell Sales People Anything

Physical – Datalink – Network – Transport – Session – Presentation – Application

2) 7 layers of OSI model in reverse order:

All People Seem To Need Data Processing

Application – Presentation – Session – Transport-Network- Datalink – Physical

3)DORA – DHCP process of Discover, Offer, Request, Acknowledge

4)Big Dogs Really Like Me – the order of K values in EIGRP: bandwidth, delay, reliability, load, MTU

5)Remembering the list of Cisco IOS log severity levels.

Every Alley Cat Eats Watery Noodles In Doors

Emergency (0)
Alert (1)
Critical (2)
Error (3)
Warning (4)
Notifications (5)
Information (6)
Debug (7)

6)To remember BGP Best Path Algorithm

We Love Oranges AS Oranges Mean Pure Refreshment.

Weight (Highest is Better)
LOCAL_PREF (Highest is Better)
Originated Locally
AS_PATH (Shortest Wins)
ORIGIN Type (IGP is Lower than EGP and EGP is Lower than Incomplete)
MED (Lowest is Better)
Paths (External > Internal)
RID (Router ID – Lowest is Better)

Thanks for reading 

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