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Technical News & Discussion => Windows News & Discussion => Topic started by: davej99 on Feb 24, 2009, 10:19:20

Title: Jumbo Frames and Broadband
Post by: davej99 on Feb 24, 2009, 10:19:20
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?
:dunno:
Would appreciate some expert insight.
Thx Dave.
Title: Re: Jumbo Frames and Broadband
Post by: Rik on Feb 24, 2009, 10:23:35
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.
Title: Re: Jumbo Frames and Broadband
Post by: uxbod on Feb 24, 2009, 10:30:46
From the switch to the router would be 100Mb.
Title: Re: Jumbo Frames and Broadband
Post by: davej99 on Feb 24, 2009, 10:38:47
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?

Title: Re: Jumbo Frames and Broadband
Post by: uxbod on Feb 24, 2009, 10:47:12
IMHO it will split the frame up into standard size ones.
Title: Re: Jumbo Frames and Broadband
Post by: davej99 on Feb 24, 2009, 16:42:17
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!
Title: Re: Jumbo Frames and Broadband
Post by: Rik on Feb 24, 2009, 16:50:14
I suppose it's linked to the same handshaking that defines the transfer speed, Dave.