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Switches, Hubs, and Modems
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Undersized/Giant Packets

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Luca Mondin
Occasional Visitor

Undersized/Giant Packets

I have a lot of errors in the events page of my procurve software of kind "Too many Undersized/Giant Packets on port xy.
On that port I conneceted an IBM AS400. Usually this problem verified during the night bakcup.
Please anyone could explain me why this problem occurs.
Any help is appreciated.

Thanks in advance,
Mohieddin Kharnoub
Honored Contributor

Re: Undersized/Giant Packets


A non-jumbo port will generate â Excessive undersize/giant packetsâ in event log, if the port is working on a speed of 1 Giga, and and it must be configured to forward Jumbo packets.

What you need is to enable Jumbo frames support on this port xy Vlan.

Switch(config)#vlan < vid > jumbo

Good Luck !!!

Science for Everyone
rick jones
Honored Contributor

Re: Undersized/Giant Packets

While an MTU mismatch could result in the switch perceiving giant packets on a port, if the host isn't trying to use jumbo frames, the undersized packets _might_ be indicitive of a duplex mismatch. But that is just a guess. Unless you know that autoneg is fubar on the AS400 system, probably best to have everything set to autoneg.
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