sorry if I put this in the wrong section, feel free to move it, but I hope you could help me here.
I have a gigabit network running with 2 NAS (1 Linkstation Pro, 1 Linkstation Live) and 2 Windows XP PCs, both with Marvell Yukon Gigabit NIC on board.
As Switches I have a Netgear GS608 (Rev2) and a Linksys SLM2008, both support up to 9k Jumbo Frames.
For toubleshooting only one of the switches is connected to the setup.
Now the Jumbo Frames story:
When I set both Linkstation to Jumbo Frames (4k or 7k for example) I can see that packets > 1514 are going fine over to the other Linkstation. (ping test with larger packets works fine)
Write transfer from NAS to NAS via FTP is 40% higher than without Jumbo Frames.
=> My Switch is working with Jumbo Frames (even a friend double checked my switch in his network which also runs under Jumbo Frames, but with Macs) and works fine with the Linkstations running with Jumbo Frames.
Setting Jumbo Frames in the Windows XP PCs NIC properties to 4k or 9k Whireshark tells me in the interface details the MTU size is 4k, 9k according to the settings I did.
Anyhow, when I try to do a ping with a greater packet (ping -f -l 2000 <NAS-IP-or-other-PCs-IP>) it results in the message that the packet cannot be send as the DF-Flag is set.
Snooping the traffic with Whireshark I do not see any (TCP) packets passing over to the remote NAS/PC. The ARP packets back and forth for revealing the MAC address of the destination acoording to the called IP work fine.
Transferring files from the NAS to PC (or vice versa) I see that all TCP packets have 1514 byte size, so nothing about the expected Jumbo Frames.
Is there an additional setting I have to make in Win XP except for the one in the NIC properties?
I tries some changes in the registry, but none worked so far, so I rolled them back.
I use Comodo Firewall as the personal firewall. Also disabled it for testing. => no change.
I am quite frustrated ... do you have any ideas?