Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches

The Catalyst 3750/3560 series switch can support up to eight compatibly configured Ethernet interfaces in an EtherChannel. The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 8 Gbps (Gigabit EtherChannel) between your switch and another switch or host. With Cisco IOS Software Release 12.2(20)SE and earlier, the number of EtherChannels has a limit of 12. With Cisco IOS Software Release 12.2(25)SE and later, the number of EtherChannels has a limit of 48.

EtherChannel balances the traffic load across the links in a channel through the reduction of part of the binary pattern that the addresses in the frame form to a numerical value that selects one of the links in the channel. EtherChannel load balancing can use MAC addresses or IP addresses, source or destination addresses, or both source and destination addresses. The mode applies to all EtherChannels that are configured on the switch. You configure the load balancing and forwarding method with use of the port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac} global configuration command.

You can find out which interface is used in the EtherChannel to forward traffic based on the load balancing method. The command for this determination is test etherchannel load-balance interface port-channel number {ip | mac} [source_ip_add | source_mac_add] [dest_ip_add | dest_mac_add].

Issue the show etherchannel load-balance command in order to check the frame distribution policy. You can determine which interface in the EtherChannel forwards traffic, with the frame distribution policy as a basis. Issue the remote login switch command to log in remotely to the Switch Processor (SP) console in order to make this determination. Then, issue the test etherchannel load-balance interface port-channel number {ip | l4port | mac} [source_ip_add | source_mac_add | source_l4_port] [dest_ip_add | dest_mac_add | dest_l4_port] command.

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml#catalyst

These are some examples:

  1. 6509#remote login switch
        Trying Switch ...
        Entering CONSOLE for Switch
        Type "^C^C^C" to end this session
    
        6509-sp#test etherchannel load-balance interface port-channel 1 
        ip 10.10.10.2 10.10.10.1 
    
    !--- This command should be on one line.
    
        Would select Gi6/1 of Po1
    
         6509-sp#
  2. 6509#remote login switch
        Trying Switch ...
        Entering CONSOLE for Switch
        Type "^C^C^C" to end this session
    
        6509-sp#test etherchannel load-balance interface port-channel 1 mac 
        00d0.c0d7.2dd4 0002.fc26.2494 
    
    !--- This command should be on one line.
    
        Would select Gi6/1 of Po1
    
         6509-sp#
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Cisco – Interpret the Serial Number

http://www.cisco.com/en/US/products/hw/optical/ps2006/products_tech_note09186a0080094523.shtml

The serial number is defined as such:

  • FAA—Flextronics, San Jose, CA. (Depending on the manufacturer, these first three digits can vary.)
  • NN—The number of years Flextronics has been a Cisco supplier. (For products built in year 2004, the number is 07.)
  • NN—The week number the product was built.
  • XXXX —A unique identifier.

 

 

From http://www.networking-forum.com/viewtopic.php?f=36&t=27266 :

Do a “show inv” that will show you the serial number.

The serial number looks like this:
ABC0011A1B2

The ABC represents the manufacturer/assembler of the part.
The 00 represents the year it was made, starting with 00 for 1997, 01 for 1998, etc.
The 11 represents the week it was made.
A1B1 is the unique portion of the serial number.