>XOR based on the last 3 bits of the source and destination MAC address.

I'm not sure about above meaning.Excuse me but,please let me know more easily.If possible,please use an example.

regards.

To answer some of your questions:

1) No difference in load balance between Static and LACP LAGs.
2) The 33xx series uses an XOR based on the last 3 bits of the source and destination MAC address. In addition it will dedicate one port in each LAG for all Unknown, Broadcast, and Multicast traffic.

There is no way to configure the switch to choose a specific port in the LAG, the XOR is done automatically.

An XOR is a comparison of two bits, if the bits are the same it equals 0, if they are different it equals 1.

The 33xx series uses the last three bits of the source and destination MAC address, this results in eight possible combinations, hence the pre-configured eight Port Channels.

So, for example, if the source address had the last three bits of 001, and the destination address had the last three bits of 011, you would first XOR them to get:

001
011
---
010

Then, convert to decimal, add one, and that would be the port member. In this case 010 = 2, plus 1, equals Port member 3 (You add 1 so you don't get a Port Member zero).

The above is in a case where you are using eight ports. If you only had a two port LAG, the switch will only use the last bit. A four port LAG would use the last two bits, etc.

Thanks for your explanation.

>Then, convert to decimal, add one, and that would be the port member. In this case 010 = 2, plus 1, >equals Port member 3 (You add 1 so you don't get a Port Member zero).

I understood that the answer was 3. But it's not clear how you would use this number 3.

Please explain me how this number 3 is used for loadbalance.

And this consideration is only for 33xx ? How about 52xx ?

 

regards.

Thanks for your answer!  But I can't understand.

>it will use only one physical link, you do not actually get the bandwidth of all the port >combined.

Really ? I thought PowerConncet could combine the bandwidth of all port like Cisco catalyst in LAG. What is the advantage of LAG ? Is it only loadbalance and failover ?

> If you started a second file transfer with different units, the XOR may end up putting the >traffic on a different LAG port. 

Sorry. I 'm not sure above explanation. I can't understand how the result of XOR(last 3 bit of source and dest mac address) choose the destination to do a loadbalance.

Please teach me again.

You really cannot use this number. By Port member I am referring to the the actual physical port used to send the traffic. When using a LAG you still have to send traffic down one physical link, so the XOR is used to decide which physical link to send the data for each stream.

So, for example, if you have only one file transfer crossing the LAG (one source address to one destination address) it will use only one physical link, you do not actually get the bandwidth of all the port combined. If you started a second file transfer with different units, the XOR may end up putting the traffic on a different LAG port.

Bottom line - there is no way to configure the switch to put certain traffic on certain LAG ports. By understanding how the XOR works, you can calculate which physical ports the traffic will take between two different devices. Does this help? Not a whole lot. Overall the solution does a good job of keeping traffic balanced, and because it uses source+destination in the calculation, you can even send multiple sources to a common destination, or vice versa, and maintain load balance.

The 52xx series, I believe, only uses the last two bits in its XOR calculation, thus the maximum of four (4) ports in a LAG. It also uses the same XOR source+destination calculation.

The PowerConnect LAG does combine the bandwidth of the ports. The nature of a LAG dictates that each stream of data has to use only one physical port, but if you have multiple streams then each takes a different port in the LAG. This concept of using XOR to determine which port the stream will take is industry standard, Cisco documentation explains they use the same process in EtherChannel.

When using binary, 3 bits will allow up to 8 combinations. Each combination represents one physical port of the LAG. So when the last three bits of the source and destination are XOR'ed the result can be mapped to a physical port:

000 = Lag member 1
001 = Lag member 2
010 = Lag member 3
011 = Lag member 4
etc..

I hope this finally helps clear it up. If you are still unsure of how XOR works or how a LAG uses the XOR results to assign data streams to physical ports I recommend doing some research. At this time we do not have any white papers available describing the details of this process, but the web has plenty of resources that cover this industry practice.

I appreciate your answer. If there's a mailing list of Dell PowerConnect,I want to join.

May I understand that PC33xx use last three bits of source and destination MAC address and

PC52xx use last two bits of source and destination MAC address to do loadbalance ? Right ?