05-12-2008 05:46 PM - edited 03-05-2019 10:55 PM
hi every body!
I read in cisco book that maximum size for ethernet frame is 1518 byte.
My question is why? it should be larger than 1518 because:
(assuming mtu=1500)
ethernet(dix)header=26 byte.
IEEE ethernet(802.3) header= upto 28 bytes
IEEE 802.3 with snap= upto 35 bytes.
If we use any ethernet standard with mtu=1500, it would be above 1518 bytes.
Any idea?
thanks alot!
have a nice day!
Solved! Go to Solution.
05-12-2008 08:24 PM
Hello Sarah,
The Ethernet frame size will remain the same i.e. 1518 unless they are configured( ex vlan tagging) to understand frames gt > 1518
You cannot mix match different ethernet headers.Generally,when use different ethernet headers, MTU for the ethernet layer reduces below 1500.
Support for frame size gt>1518 are highly vendor/implementation specific.
Good info on different types of Ethernet frame formats
http://www.firewall.cx/ethernet-frames-intro.php
HTH
Padmanabhan
05-12-2008 08:24 PM
Hello Sarah,
The Ethernet frame size will remain the same i.e. 1518 unless they are configured( ex vlan tagging) to understand frames gt > 1518
You cannot mix match different ethernet headers.Generally,when use different ethernet headers, MTU for the ethernet layer reduces below 1500.
Support for frame size gt>1518 are highly vendor/implementation specific.
Good info on different types of Ethernet frame formats
http://www.firewall.cx/ethernet-frames-intro.php
HTH
Padmanabhan
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