HA and loadbalancing

Unanswered Question
Oct 29th, 2008

Hi, I need to desing High Availibility for a medium size network, for that I need to know the technical difference beteen 3750 and 4500 switches, will the first one supports both the things.

Kindly provide solution for 3750 and 4500 for attached network desing. Can 3750 be replaced by 4500 in the above situation, since we are already having 3750 switches.

Thank you

I have this problem too.
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John Blakley Wed, 10/29/2008 - 08:54

At the current company I'm at now, we have a 3750, but the previous company that I was at we had 2 4705R. The 4705, IMHO, is a much better switch, and it can definitely replace your 3750 in this scenario, and in many ways be better.


bishnbaajee Wed, 10/29/2008 - 09:40

Thank you for your response, but I need to know which one is prefereble, stackble HA using 3750's or IP based HA using 4500 series, and what is the advantage.

Kindly provide the solution with both the senarios.


francisco_1 Thu, 10/30/2008 - 02:19

there are benefits with stacking but in your case i would go for the 4507 using maybe HSRP or GLBP for HA host loadbalacing. with the 4507 you have more backplane bandwidth, more ports density, scalable. With the 3750's how do you physically connect them to get full redundancy? not easy an question to answer.


bishnbaajee Thu, 10/30/2008 - 07:15

Thank you, but I need to provide justification to replace 3750 to 4507. for that I need the technical differences of both.

Kindly suggest...

bishnbaajee Thu, 10/30/2008 - 08:13

i need to configure GLBP bwteen the 4507 switches which is connected to servers and access switches 2950*5.. what i should add to my sample configuration..kindly provide.


John Blakley Thu, 10/30/2008 - 08:22

You need to add the preempt command on your secondary switch.

glbp 100 ip

glbp 100 priority 100

glbp 100 timers msec 200 msec 700

glbp 100 preempt

IF the primary switch goes completely down, then glbp will kick over to the second switch. You can also have the forwarder switch if your line protocol goes down on the other end by:

global config:

track 100 inter po1 line-protocol (check syntax)

in your etherchannel interface on both switches you can weight them:

glbp 100 weighting 50 lower 20 upper 50 (this means that 50 is the weight, if the weight goes lower than 20, then it will move traffic to the other AVF, if it regains between 20 - 50, then it will forward out this AVF.)

glbp 100 weighting track 100 decrement 30 (this is from memory too).


bishnbaajee Thu, 10/30/2008 - 08:35

could you please provide a link to chek the cofig example..for ether channel and GLBP complete sytax..



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