Multi-ISP load balancing and HSRP failover or GLBP?

[tkatsiaounis]

Hello.I have the following problem.I have three different isp lines and i want to use all of them on two routers with HSRP for maximum redundancy.All of my lines end with an rj45 cable and i want to put all of them on a switch and behind the switch connect my two routers with HSRP. More specifically i have one 4mbps line one multilink 2x2MBps and one leased 20 MBps. Can i use all three of them on the same time? Sample schema is

line1 line2 line3

switch

router 1 router 2

Both routers are Cisco 3845 and switch is catalyst 2960G 24TC-L.Should i better use GLBP?

Any help will be great cause i am confused.Any details you might need don't hesitate to ask.

Thanks in advance.

[Rupesh Kashyap]

You can do this only if you are using GLBP.

[tkatsiaounis]

Ok Thanks.

Any configuration guidelines?

I forgot to mention that one line is not for internet access it is for some branches we got.Is that a problem?

[Giuseppe Larosa · Accepted solution]

Hello Theofanis,

the problem is that usually each ISP will provide to you a different ip address and ip subnet.

You can do this but you need to think on using three Vlans, three Vlan subifs on each router, and one HSRP or GLBP group for each Vlan.

However to be able to use HSRP or GLBP the ip subnet cannot be a /30 because at least four hosts are needed :

isp router ip address, HSRP VIP, R1 ip address, R2 ip address.

Verify with your ISPs if they are providing you this.

Usually an ISP gives you a /30 for the link and a /29 or /28 for the internal LAN.

If so this schema cannot be implemented and you need to put two ISP links on one router and one link on the second router.

You can use GLBP on the client vlan if multiple clients exist to perform some load balancing outbound.

About connecting all the links directly to the lan switch be aware that it will be a single point of failure.

Hope to help

Giuseppe