Jumbo Frames and Broadband

[davej99]

Just invested in a new Gb  ethernet Laptop, NAS and switch. My question is what happens when I connect the switch to my 100Mb modem/router with jumbo frames switched on? Will the whole NW revert to 100Mb? Will the gateway give up? Will I get fragmentation problems? Does it matter?

Would appreciate some expert insight.
Thx Dave.

[Rik]

TBH, Dave, I have no idea. To my mind, the two systems should cohabit perfectly, as a 10 & 100 Mbps connection would, but I've never tried it to be certain. What I'd expected is that the LAN would chunter along at 1Gb, while the WAN works at 100Mb.

[uxbod]

From the switch to the router would be 100Mb.

[davej99]

Thx for the replies.

Uxbod, yes the switch/router has negotiated 100Mbps. My puzzle is what happens when a jumbo frame from the PC NIC destined for the internet arrives there, or does the NIC know to send regular frames?

[uxbod]

IMHO it will split the frame up into standard size ones.

[davej99]

Uxbod is right, I think. Having set Gbps cards to an MTU/Jumbo frame of circa 7K, the router gateway runs at circa 1.5K as usual. Don't ask me how!

[Rik]

I suppose it's linked to the same handshaking that defines the transfer speed, Dave.