Cisco ACE 4710 + Round Robin Predictor

[Mubasher Sultan - 2x CCIE # 20149 (R&S | Sec)]

Hi,

I am having a Cisco ACE 4710 (c4710ace-mz.A3_2_0.bin).

I have two SMTP Servers that are load balanced with VIP Address. It is a single arm configuration. (Predictor = Round Robin)

My issue is that, client is complaining that ACE is not doing a proper load balancing among two servers. Because, one server is receiving arround 500 emails while other is getting the 10 - 15 emails at the same time.

I have checked the "show serverfarm SFARM1 detail" command and found that the counter increments for the connections on both servers are increasing one by one which seems that it is fine.

But, client is expecting that emails receiving ratio should be in equal proportion 1:1. Is it possible?

Please comment or any idea...

--

Kind Regards,

Mubasher

[Gilles Dufour]

The loadbalancer loadbalances connections not emails.

So, if the connections are splitted equally ACE is doing its job right.

Nothing else you can do.

Gilles.

[Mubasher Sultan - 2x CCIE # 20149 (R&S | Sec)]

Hi Gilles,

Thanks for the reply,

This is correct that what you mentioned but i was thinking to changed the predictor to "least connections" because the customer was complaining that one server is exhausted with no. of emails (500 emails) and became down one time.

I want to make some tests and clarify the situation that ACE is working fine. Please advise that shall I change predictor to “least Conn” and can it be done online or does require any disconnection or downtime?

Any other idea or suggestion...

B. Regrds,

Mubasher

[Gilles Dufour]

You can give a try to leastconn.

The change can be done live.  No downtime required.

Gilles.

[Mubasher Sultan - 2x CCIE # 20149 (R&S | Sec)]

Hi,

Could you please see the attached config and adivse me more.

Looking for any comments.

Thanks,

Regards,

Mubasher

[sdoremus33]

One thing I found was under policy map

policy-map multi-match VLAN10

  class VS-ETmail

    loadbalance vip inservice

    loadbalance policy PM-Mail

    loadbalance vip icmp-reply

    nat dynamic 1 vlan 10

Also do you have multiple service-policies in your configuratin if so you can also add

policy-map multi-match "name"-vip Note: make sure you add -vip to the policy-map name.

Also with RR Cisco ACE LB will work in one of two ways

1. Per-Packet:

2. Per-Destination: Most apps use this method

You can also setup capture statments to the rservers to get  better understanding of packet flow.

Have you also tried another route: TCP Least connections., etc....HTH