Fwd: Some questions about Link Aggregation and Failover

Jon Radel jon at radel.com
Fri Mar 9 14:53:14 UTC 2012

On 3/9/12 4:08 AM, Damien Fleuriot wrote:
> Well that's exactly what I'm trying to show you.
> Link aggregation will *NOT* allow you to get 200mbs between 2 servers by
> sending data over the 2 cables.
> As per the example I pasted below, link aggregation uses a load
> balancing algorithm to share the traffic across several links.
> It will *NOT* use *BOTH* links for a single "source ip - destination ip"
> pair.

All of which is explained at least twice in the document the OP claims 
to have used


once in the section on LACP:

"LACP balances outgoing traffic across the active ports based on hashed 
protocol header information and accepts incoming traffic from any active 
port. The hash includes the Ethernet source and destination address, 
and, if available, the VLAN tag, and the IPv4/IPv6 source and 
destination address."

and once in Example 32-1, which is presumably being used as the cookbook 
for this project:

"Since frame ordering is mandatory on Ethernet links then any traffic 
between two stations always flows over the same physical link limiting 
the maximum speed to that of one interface. The transmit algorithm 
attempts to use as much information as it can to distinguish different 
traffic flows and balance across the available interfaces."

Has use of Gig ethernet been considered?

--Jon Radel
jon at radel.com

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