Can we combine different kind of interface in Etherchannel?

Question

I see on Cisco guide that:

Each EtherChannel can consist of up to eight compatibly configured Ethernet interfaces. All interfaces in each EtherChannel must be the same speed, and all must be configured as either Layer 2 or Layer 3 interfaces

But when I try combining 2 fast ethernet link and 1 gigabit link in packet tracer, there is no error:

Group: 1
----------
                Port-channels in the group:
                ---------------------------

Port-channel: Po1    (Primary Aggregator)
------------

Age of the Port-channel   = 00d:00h:06m:15s
Logical slot/port   = 2/1       Number of ports = 3
GC                  = 0x00000000      HotStandBy port = null
Port state          = Port-channel 
Protocol            =   LACP
Port Security       = Disabled

Ports in the Port-channel:

Index   Load   Port     EC state        No of bits
------+------+------+------------------+-----------
  0     00     Gig1/1   Active             0
  0     00     Fa0/2    Active             0
  0     00     Fa0/1    Active             0

can anyone explain this ? thank you.

Answer 1

Packet tracer is a simulation for Network academy not a IOS emulator (like say GNS3) if there is a conflict between the doc and packet tracer, packet tracer looses. If you read further in the documentation a LOT of things have to match for an etherchannel bundle can form and link speed is one of them.

A corner case MAY be etherchannel autonegotated ports that end up at different speeds, but etherchannel will react to dynamic changes and drop ports out of the etherchannel so I don't think that will work.

Nor do you want it to as with non nexus hardware the load balance is power of 2 (3 ports will result in 1 of them getting 50% of the traffic) and there is no variable load balancing (a gig port gets 2x traffic of say 5 100 meg ports)