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GLBP vs HSRP

chee-ben.tan
Level 1
Level 1

Hi, I wonder what is the big difference between GLBP and HSRP?

Ben

1 Accepted Solution

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There is lot of advantages are there with HSRP (interface tracking, objext tracking) and the same faetures are supported by GLBP also..but the only main difference is , with HSRP , more than one gateway should be used for the traffic get loadbalanced but with GLBP no need to have multiple Gateways.....

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12 Replies 12

passioncas
Level 1
Level 1

Both are gateway redundancy protocol.But with HSRP ,for loadbalancing the traffic , we need to have multiple HSRP groups as well as multiple default gateways.With GLBP , the loadbalancing can be perfromed amongs routers with a single default gateway.....

Hope to help

Rahul

So in other words, there is no advantage using HSRP right? Might as well using GLBP in all deployment?

there is no advantage using HSRP right? Might as well using GLBP in all deployment?

Can you pls elaborate why there is no advantage of HSRP in deployment?

Because by default GLBP able to load balance two gateways while HSRP unable to do that. So my question is at what kind of scenario will be HSRP useful over GLBP?

If you have 2 connections and the requirement is that the traffic should use the first link as long as it is available.In such scenarios HSRP will be useful over GLBP ( no need for load balancing )

There is lot of advantages are there with HSRP (interface tracking, objext tracking) and the same faetures are supported by GLBP also..but the only main difference is , with HSRP , more than one gateway should be used for the traffic get loadbalanced but with GLBP no need to have multiple Gateways.....

I believe one advantage for using HSRP is if you're actually using multiple gateway routers for failover redundancy. It sounds like GLBP is good for when you have 1 gateway router, but want to load balance internally. HSRP has benefit of switching between physical routers if one of the routers goes down for whatever reason, the virtual router continues. 

Possibly you need to better choose you technical words and/or better understand these FHRPs.

For example rather than:

"It sounds like GLBP is good for when you have 1 gateway router . . ."

perhaps you intended:

"It sounds like GLBP is good for when you have 1 gateway IP address . . ."

or consider:

"HSRP has benefit of switching between physical routers if one of the routers goes down for whatever reason, the virtual router continues."

Well, it's not really a virtual router but it's a virtual IP.  Further, GLBP does such switching too, i.e. if a physical router fails, the virtual IP continues to accept traffic directed to it.

If the forgoing doesn't make sense, post a new topic question on whatever aspect(s) are unclear to you.

Award winning level of smug, snide, pedantic, and useless reply. 


@Joseph W. Doherty wrote:

Possibly you need to better choose you technical words and/or better understand these FHRPs.

OR you could just not be like this and actually be positive. 


 


@Joseph W. Doherty wrote:

 

perhaps you intended:

"It sounds like GLBP is good for when you have 1 gateway IP address . . ."

 



No I meant one router. Because HSRP is used with multiple routers. If there's something wrong I wrote, you can just help me and others understand. You don't have to be a snarky jerk. 


@Joseph W. Doherty wrote:

Well, it's not really a virtual router but it's a virtual IP.  Further, GLBP does such switching too, i.e. if a physical router fails, the virtual IP continues to accept traffic directed to it.



Did you wife leave you today? 

"virtual router"
https://www.geeksforgeeks.org/hot-standby-router-protocol-hsrp/


"virtual router"
https://en.wikipedia.org/wiki/Hot_Standby_Router_Protocol

"virtual router" 
https://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/9234-hsrpguidetoc.html

 

 

Many years ago, there was one person, somewhat had a reaction like yours, over a disagreement about the performance capability of a specific small router.  Some cannot take any critique, implying they're mistaken, no matter how it's offered.

That person eventually was banned, not for being, I believe, mistaken, or even being unwilling to accept the possibility of being mistaken, but by going down the path you've just started on.  I.e., I would suggest in future replies, you be a bit more temperate in your writing.  For example, "snarky jerk" and/or "Did you wife leave you today?".

I'll be the first to admit, I'm not the best at offering constructive critique, tactfully.  If someone says 2+2=5, my tendency is mostly to just state bluntly state 2+2=4.

Trying to be more tactful, is why I write: "Possibly you need . . ." or "perhaps you intended" or "Well, it's not really", all, implying, I hoped, I (at least) might have misunderstood what your wrote.  But, might it also be possible, you really don't understand all the nuances of HSRP and/or GLBP?  I recognize that can be difficult to accept, but whether true or not, you cannot advance in learning until you accept it might be true.

Further, I concluded with "If the forgoing doesn't make sense, post a new topic question on whatever aspect(s) are unclear to you.", i.e. I'm open to discussion.

Notwithstanding the above, there are a couple of your comments, that are worthwhile.

"If there's something wrong I wrote, you can just help me and others understand."

Yes, actually that's something I always consider.

This particular posting was initially posted 12/24/2008!

I think many of us consider adding replies to such old posts not very useful, mainly because of technology developments, since.

That's the principle reason why I didn't want to jump into lengthy explanations and also suggested any follow-up be on a new posting.

There are other reasons too.  Such as, do you really want explanations?  If not, why waste my time.

For others, assuming they see the "issues" I did in your comments, no explanation is needed.  To those that don't see the "issues", they might not actually care to know, but if they do care, they too are welcome to ask.  If they don't care, again a waste of my time.  If they do care, and ask, I'll respond, usually trying to whatever level of detail they need to answer their query.

Hopefully, the above does this for your reply to mine, but furthering explanations, let's touch upon, "virtual router", to which you provide references to its usage, all, though, in the context of HSRP.

Hmm, well let's start by an Internet search for those words or that term, "virtual router".

Does HSRP jump to the top of the search results?

Hmm, try searching for the terms "cisco" "virtual router" or words "cisco virtual router", again does HSRP jump to the top of the search results?  When I try, it does not, but results might vary based on search engine.

What such search results, show us, "virtual router" is used lots of ways with various meanings.

(One, which immediately comes to my mind, is true virtual routers, i.e. running distinctly separate router instances [not VRFs] on one physical router.  Possibly Cisco now supports that on the 9K routers, but Brand J, I believe, has had that for some time.  I also think of a router image running under an emulator, like GNS3 or CML as a "virtual router".  Of course, HSRP predates these newer technologies, or even, perhaps SVIs.  But, IMO, if you still tie "virtual router" to HSRP, without being clear about what this fully means in just a HSRP context, it can lead to confusion when you encounter the same term elsewhere.)

Your references, do indeed have the term "virtual router" but, again, in the context of just HSRP.

If you search for "virtual router" and "hsrp" you'll get references like yours, but try searching for "virtual router" and "glbp" or "virtual router" and "vrrp".  HSRP, GLBP and VRRP all run on routers, also L3 switches.  So, unless you further clarify "virtual router", how does that term, alone, distinguish a "big difference" between HSRP and GLBP?

Now, let's examine your first reference.  "virtual router" is only mentioned once, excluding the "Similar Reads" sections where it's used as "Virtual Router Redundancy Protocol (VRRP)".

Where it's used, just the one time, not in context of VRRP, is it italicized?  No!

Bolded?  No!  Text somehow highlighted?  No!

But, in the section "Some important terms related to HSRP :", we first have "1. Virtual IP :"!  Might there be a reason for this emphasis difference?  Might there be a reason why I too suggested using IP address or virtual IP rather than router or virtual router, respectively?

Is the above helpful to you?  I hope so.  There so much you can learn from others!  I've certainly have, especially in active participation.  Nothing quite like trying to answer questions, to improve your understanding about something.

BTW, I also note your account started today.  I.e. possibly you've only just started reading this site, and perhaps haven't read many of the postings I've done over the years.  Further, you might be unaware of the significance of my VIP and Hall-of-Fame awards.  Neither make me an "expert", both are mostly awarded for active assistance, the latter, generally, for a long, long time.  So, (especially) because of those, you might give me the benefit of the doubt, that if my reply appears "smug, snide, pedantic", in may just be by appearance, and not intention, and maybe not as "useless" as it appears either.  In other words, I'm probably not a "jerk", although "snarky", maybe.  Regarding my wife leaving me today, that's ridiculous, I didn't even beat her once today.  ; )

BTW, since @promontorium re-activated this topic question, possibly reading Cisco's own whitepaper description of GLBP - Gateway Load Balancing Protocol, might be helpful.  In the section GLBP has:

The Gateway Load Balancing Protocol feature provides automatic router backup for IP hosts configured with a single default gateway on an IEEE 802.3 LAN. Multiple first hop routers on the LAN combine to offer a single virtual first hop IP router while sharing the IP packet forwarding load. Other routers on the LAN may act as redundant GLBP routers that will become active if any of the existing forwarding routers fail.

GLBP performs a similar, but not identical, function for the user as the HSRP and the VRRP. HSRP and VRRP protocols allow multiple routers to participate in a virtual router group configured with a virtual IP address. One member is elected to be the active router to forward packets sent to the virtual IP address for the group. The other routers in the group are redundant until the active router fails. These standby routers have unused bandwidth that the protocol is not using. Although multiple virtual router groups can be configured for the same set of routers, the hosts must be configured for different default gateways, which results in an extra administrative burden. GLBP provides load balancing over multiple routers (gateways) using a single virtual IP address and multiple virtual MAC addresses. Each host is configured with the same virtual IP address, and all routers in the virtual router group participate in forwarding packets. GLBP members communicate between each other through hello messages sent every 3 seconds to the multicast address 224.0.0.102, User Datagram Protocol (UDP) port 3222 (source and destination).

The second paragraph, of Cisco's description, above, describes what's truly different about GLBP vs. HSRP and VRRP.  The key  (technical) "big difference" is, GLBP supports "multiple virtual MAC addresses", as HSRP, VRRP and GLBP all support a "single virtual IP address".  This section also explains the "big difference" (advantage of) GLBP, when you want to do gateway load balancing.

(NB: I also recall [?] GLBP offered some additional features unique to it until HSRPv2 was released.  One feature of GLBP, often overlooked, is you can customize its load balancing, including, I believe, effectively, disabling it [leaving it acting much like HSRP - and if possible, why would you do this - again, I recall, initially it had a few features not available with the concurrent HSRP available at the same time - I also recall HSRPv2 soon followed - 12.2.14S vs. 12.2.25S].)

Lastly, although @promontorium (correctly!) references "virtual router" is used in descriptions of HSRP, an open source FHRP, that supposedly can do both HSRP and GLBP functions, in its Wiki description, Common Address Redundancy Protocol doesn't appear to use the term "virtual router", at all, describing its function.  My guess, this might be to avoid all the "baggage" that can come along with the term "virtual router", in current usage, which likely wasn't an issue when Cisco was initially trying to explain the function of HSRP (back last century).

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