I recently changed the EtherChannel load-balance algorythm on some 3750 switches and lost connectivity. The switches are running the IP Services code and the EtherChannels are Layer-3 and spread over two switches in a stack (Port-Channel 1 is G1/0/1 & G2/0/1 and Port-Channel 2 is G1/0/2 & G2/0/2). They were configured with the default src-mac load-balance algorythm which obviously on a routed link has no load balancing effect since the source MAC never changes. I changed this to src-dst-ip and some hosts lost connectivity - i.e. I could ping from one VLAN to hosts somewhere in the rest of the network and from another VLAN I couldn't. The OSPF adjacencies stayed up on the stack so I am a bit lost as to why the connectivity failed. The load-balance decision is performed locally by the switch so why should I have lost connecivity?
Since this was a live network I removed the command to restore connectivity.