When you issue a command show port 3/1 on an Ethernet port, you observe the ‘Giants’ column has a non-zero entry.
What could cause of this?
A.
IEEE 802.1Q
B.
IEEE 802.10
C.
Misconfigured NIC
D.
User configuration
E.
All of the above
Explanation:
The 802.1Q standard can create an interesting scenario on the network. Recalling that the maximum size for an Ethernet frame as specified by IEEE 802.3 is 1518 bytes, this means that if a maximum-sized Ethernet frame gets tagged, the frame size will be 1522 bytes, a number that violates the IEEE 802.3 standard. To resolve this issue, the 802.3 committee created a subgroup called 802.3ac to extend the maximum Ethernet size to 1522 bytes. Note: The show port command is used to display port status and counters. Giants denote the number of received giant frames (frames that exceed the maximum IEEE 802.3 frame size) on the port.
Reference: Trunking between Catalyst 4000, 5000, and 6000 Family Switches Using 802.1q Encapsulation
http://www.cisco.com/warp/public/473/27.html
Giants Description:
CatOS sh port and Cisco IOS sh interfaces and sh interfaces counters errors. Frames received that exceed the maximum IEEE 802.3 frame size (1518 bytes for non-jumbo Ethernet) and have a bad Frame Check Sequence (FCS). Common Causes: In many cases, this is the result of a bad NIC. Try to find the offending device and remove it from the network. Platform Exceptions: Catalyst Cat4000 Series that run Cisco IOS Previous to software Version 12.1(19)EW, the giants counter incremented for a frame > 1518bytes. After 12.1(19)EW, a giant in show interfaces increments only when a frame is received >1518bytes with a bad FCS.
link
http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015bfd6.shtml