Cisco SG200-50 and RedHat EL Bonding

[MrSchorsch]

Hi there,

I've configured a network with 5 (and more Servers later). Each Server has 4 1GB Network interfaces, configured to bond.

I'm using balanced-XOR mode so this doesn't need special switch configuration.

Now I want to add some fault tolerance, therefor I want to add a second switch (SG200-50) and put two links from each server to both switches.

The switches should be connected with 4 links as LAG Group.

Is it possible to get fault tolerance AND load balancing over more than one switch in mode "balanced XOR"? Also is this possible by using SG200 Series?

What do I need to configure, I'm not as familar with Cisco Switches.

Kind regards

Georg

[cchamorr]

Hello, 

I'm not really sure I understand your question completely but I do know how the SG200 Small business switches work so I will provide some information that could be helpful for you.

First of all, here is the administration guide for the devices:

http://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbss/sf20x_sg20x/administration_guide/78-21139.pdf

On page 116 you will find the information about How to configure LAGs on the device.

It explains the load balance methods the switch can use.

In short, yes, you can configure LAG's on the switches. Yes, it will provide redundancy. Yes, it does perform load balance.

I would recommend to check the section on the admin guide and let us know if you have any questions.

For better understanding, here is a link to a demo interface for that device:

http://www.cisco.com/assets/sol/sb/SG200_Emulators/SG200_Emulator_v1-2-9/config/home_SG_200-50P_1_2_9.htm

It is not on the latest firmware version but it will give you a very good idea on how it works.

I hope this helps.

[MrSchorsch]

Hi,

thanks for your answer. I allready know the Sg200 can configure LAGs.

I've tested in past. For mode Balance-xor on my servers, I've understand, its not neccessary to configure LAG on those portgroups.

At this time, all 4 links from one Server are connected to one switch, means this switch has up to 20 links for 5 Servers.

this works really fine, load balancing seems good and so on. But if this switch fails, the hole network is inoperable. Therefor I want to add a second switch. I want to link each switch with two lines from each server.

At all I want to have load balancing and fault tolerance over both switches. Same like in my actual one switch setup.

Don't know whether this is possible?

[Michal Bruncko]

> Therefor I want to add a second switch. I want to link each switch with two lines from each server.

I hope that in general this will work - as you said - without having LAG/LACP channels in place. The only problematic situation could be that one of that switches lost uplink NW connectivity but it stays in operable state. This will cause that half part of your communications could be affected as your server will not be able to identify that kind of connection failure. Yes, in case that second switch will go down completely - which results in server links state transitions to DOWN, all existing communications will be moved to rest two active links.

To avoid situation described before it would be fine to have both switches in single stack (i.e. having same control and data bus) - which means if one stack member switch lost uplink connectivity, second member switch can still be used to provide it without affect to production traffic.

But as I remember only SG500 switches provides stacking capability.