[ovs-discuss] Simple IP load Balancing

[Ritesh Rekhi]

Hi Diego,

Thanks for the reply once again.

You are right 8 entries are not enough. My explaination was just to explain you my design.I can have 255 buckets also which will be more better.

I have a follow up on the way you told me to implement .Is it possible to match last 8 bits on source-ip  by giving mask like 0.0.0.1 or 0.0.0.2 or 0.0.0.3.

In all the OVS manuals you can only do a match to ignore last bits i.e 192.168.1.1 255.255.255.0

Sorry I am new to OVS .That's why these questions.

My idea is that if webserver gets overwhelmed it can send an event to controller to take it out and when load is less it can add itself.

Ritesh

From: Diego Rivero [mailto:riverod9 at gmail.com]
Sent: Monday, August 05, 2013 11:10 AM
To: Ritesh Rekhi
Cc: discuss at openvswitch.org
Subject: Re: [ovs-discuss] Simple IP load Balancing

Hi,

I don't know if there is any method to implement hash function as you need. Because as far as I know the OpenFlow rules are stateless. In case you want to achieve such functionality with only source IP address, set IP address mask to extract 3 bits so that you can pick up the number from 0 to 7 which depends on the source IP address. I have never tried this so you need to test it. Besides that why do you want to do load-balancing with only source IP address? For me it seems that the load of each web server gets unbalanced easily. Moreover I cannot see big advantages to set only 8 flow entries.

Diego

On Mon, Aug 5, 2013 at 11:46 PM, Ritesh Rekhi <rrekhi at paloaltonetworks.com<mailto:rrekhi at paloaltonetworks.com>> wrote:
Hi Diego,

Thanks for replying.Let me explain more on my design.

Let's say you have 8 servers to which you load balance with ip's 2.2.2.1 to 2.2.2.8 and they all are web servers. Now client 1 which is IP 45.45.45.45 comes i.e tcp syn we has the source-ip and come up with a number 1-(through hash to bucket function) and then changes dest ip to one of the servers and send packet out to that port, we also add the flow table entry  where it is matching hash of source-ip and change dest-ip based on the hash.

The reason I want to do hash to bucket function is that I don't know which source-ip's can come and I want same source-ip to go to same server always.With hash to bucket approach there are 2 advantages I only need 8 entries for all the source-ip's in this world and secondly I don't have to send all the packets to controller to make a decision.

With your approach I need to add flow table entries for each source-ip and that will be too much.

Thx
Ritesh


From: Diego Rivero [mailto:riverod9 at gmail.com<mailto:riverod9 at gmail.com>]
Sent: Monday, August 05, 2013 5:44 AM
To: Ritesh Rekhi
Cc: discuss at openvswitch.org<mailto:discuss at openvswitch.org>
Subject: Re: [ovs-discuss] Simple IP load Balancing

Hi,

I don't fully understand your design but it might be better to keep the list of the IP address and the MAC address of the bucket somewhere in an OpenFlow controller. When packet_in for the first time, go through the list and decide which bucket to send the packet to.

Diego,

Sent from my iPhone

On 4-ago-2013, at 10:32, Ritesh Rekhi <rrekhi at paloaltonetworks.com<mailto:rrekhi at paloaltonetworks.com>> wrote:
Hi all,

I want to make a simple Load balancer where I want to change the destination IP for the request and for response change the source-ip.

I can do that easily if I know the source-ip's but I want to do it by hasing source-ip to a bucket and then based on bucket change dest-ip for the request .That way all packets with same source-ip can go to 1 given dest-ip.

Do we have any function where we can hash a field and assign it to a bucket?

Are there any plans to implement any hash to bucket algo?

Thx in advance
Ritesh


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