[c-nsp] How can I increase Ethernet MTU?

Victor Sudakov vas at mpeks.tomsk.su
Wed Jan 28 03:59:38 EST 2015

Victor Sudakov wrote:
> There is one more point. Some switches are connected via
> communications equipment (e.g. iPASOLINK radio relay) rather than
> directly. Those switches' GigabitEthernet ports are running in the
> 100Mb/s mode because the iPASOLINK equipment has FastEthernet ports
> with maximum frame size = 2000.
> Does the "system mtu jumbo" affect GigabitEthernet ports in 100Mb/s
> mode? Is anything larger than 1500 supported in 100Mb/s mode on Cisco?

I have created a small lab http://i.imgur.com/D13GBeL.png with the
switches I had at hand.

The result is positive. Two GigabitEthernet ports, even if working in
100Mb/s mode and connected via equipment with FastEthernet ports only,
do forward jumbo frames (1600 bytes in my lab).

Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru

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