Real servers &VIP on same subnet - sticky? redundency ?

Unanswered Question
Feb 25th, 2007

Good Day,

I am a learner in content networking, & currently working on a Design requirement involving ? request assistance from the experts again.

In my scenario, the clients will hit the VIP on port 80/81, and the CSS shall load balance between 2 IIS servers via L2 switches. I shall use Cisco CSS 11503?s in redundancy.

The servers and the VIP should be on the same subnet and the CSS should also perform session stickiness and also have redundancy between the CSS?s.

The setup might look something like this.

User port -80/81



_ L3_

| |


| |


| |

Srv1 Srv2




What are my options for redundancy?

Can I do VIP redundancy on the client side, where traffic is coming in & do interface redundancy on the server side and using the redundant interface IP address as the default gateway for the servers OR, should I be looking at Box-to-Box redundancy option.

What are my options for sticky, as we will only use HTTP on port 80/81

I was planing of using Arrow point cookie or sticky srcip.

Note: Real servers and the VIP shall use the same subnet. how is the sticky and redundency compatibility in this case?

Request your Advice,


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andreas.larsen@... Mon, 02/26/2007 - 00:25

1. Options for redundancy. I would go for VIP and interface redundancy. Drawback with that is that you will have to do configuration on both CSS identical. But you can share the load between them if you want to.

2. I would go for sticky on cookie if I where you. Src IP isn't as good if you have to fail a server and you have alot of clients hiding between the same ip address ( proxy ) all thoose will fail to another server. If you do have session failover on the Webplatform that isn't such a big issue. But in general I find it better to do sticky on cookie.

3. Real servers and VIP on the same network is no problem really. It will work the same way. Redundancy and sticky will be the same.

Rate if you find this usefull please

gagansethi Mon, 02/26/2007 - 01:30

Thanks Andreas,

I shall also like to prefer vip with interface redundency .. but can it be done with one subnet only? i.e. the server subnet.

second, do you mean arrowpoint cokie.. when u say sticky on cookie ?

will you call such a scnerio as ONE ARM... also, what if i want to add another pair of server for a new l/b enviornment. and they too are from the same subnet as the first pair of servers(1st enviornment)

will this be no problem.



andreas.larsen@... Mon, 02/26/2007 - 04:07

1. Yes that can be done on one subnet. however I would have interface redunancy on the other interface also with some sort of reporter that checks that the upstream router/firewall is alive.

2. Either you do a cookie insert or you let the webserver set the cookie.

3. Not sure about the name of the scenario. But adding more servers to the same subnet isn't a problem as long as you have enough ip address for VIP and hosts =)


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