jumbo frame question

mcveigh

Diamond Member
Dec 20, 2000
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I installed a new SMCGS24C-SMART switch for a network with only a few gigabit devices.
the main one being the file server and a graphics workstation.

the other 6-8 users connect to a database on the server (small)
everything works fine. and I think I see a slightly faster performance of the database from the endusers PC when everyone is accessing it.
the old switch was an ancient no-name 10/100 model.

I enabled jumbo frames on the server, switch, and 2 PC's. I thought doing this would lead to problems as not everyone was GB w/ jumbo frames.

but everything still works fine. I haven't done any in depth testing of it, waiting till after new years.
Is the switch just compensating maybe breaking down the packets in to smaller chunks?

EDIT: I may setup 2 VLAN's but was just wondering if I am opening up a can of worms the way I have it now
 

spidey07

No Lifer
Aug 4, 2000
65,469
5
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TCP applications aren't affected by the difference in frame size. the 3-way handshake the TCP uses to setup the connection includes the max segment size (MSS).

So you're stations with 1500 byte frames will use a MSS of 1460 as will the server for that TCP connection. applications that don't use TCP could be affected. The switch isn't doing anything special unless it is routing - then the router will break up the packet into smaller fragments.
 

mcveigh

Diamond Member
Dec 20, 2000
6,457
6
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OK that is good.

I may turn them off anyways. or setup the VLANs I'd rather not have any issues
 

JackMDS

Elite Member
Super Moderator
Oct 25, 1999
29,516
408
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The PCs with the Jumbu frames enable might have a reduction in Internet Bandwitdh if they conncets directly to a Cable/DSL Router.
 

mcveigh

Diamond Member
Dec 20, 2000
6,457
6
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they all go thru the switch then the router is connected to the switch
 

Madwand1

Diamond Member
Jan 23, 2006
3,309
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Everything should be fine with TCP. To check this for yourself, you could set up Wireshark or something similar and look at the frame sizes.