Cisco Cisco IOS Software Release 15.2(3)E

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You should review this section before you begin working with the switch. These are known limitations 
that will not be fixed, and there is not always a workaround. Some features might not work as 
documented, and some features could be affected by recent changes to the switch hardware or software.

Traffic on EtherChannel ports is not perfectly load-balanced. Egress traffic on EtherChannel ports 
are distributed to member ports on load balance configuration and traffic characteristics like MAC 
or IP address. More than one traffic stream may map to same member ports based on hashing results 
calculated by the ASIC.

If this happens, uneven traffic distribution will happen on EtherChannel ports. 

Changing the load balance distribution method or changing the number of ports in the EtherChannel 
can resolve this problem. Use any of these workarounds to improve EtherChannel load balancing:

–

for random source-ip and dest-ip traffic, configure load balance method as src-dst-ip

–

for incrementing source-ip traffic, configure load balance method as src-ip

–

for incrementing dest-ip traffic, configure load balance method as dst-ip

–

Configure the number of ports in the EtherChannel so that the number is equal to a power of 2 
(i.e. 2, 4, or 8)

For example, with load balance configured as dst-ip with 150 distinct incrementing destination IP 
addresses, and the number of ports in the EtherChannel set to either 2, 4, or 8, load distribution is 
optimal.(CSCeh81991)

When the rate of received DHCP requests

exceeds 2,000 packets per minute for a long time, the 

response time might be slow when you are using the console. 

The workaround is to use rate limiting on DHCP traffic to prevent a denial of service attack from 
occurring. (CSCeb59166)