Microservers disconnect after installing gigabit switch

Soldato
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I've replaced a 10/100 hub with a Netgear Gigabit Switch. I have two HP microservers running Synology DSM 4.2.

When I ping them from my pc only one of them is accessible at any time and this for only a few seconds until it times out and for the other to reply. Another few seconds and they swop over again.

Any ideas?
 
Soldato
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Manually. The only change is the new switch. Taking either one off the network means the other works as normal.

Putting the old hub back in place and everything works.
 
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Soldato
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But if the MACs are the same then that'll cause issues. Could be the old hub is dumb enough to let you off with it but the new switch is smart enough to haul on the reins and complain about it.

You'll need to change one of the MACs. I'm rusty with XPenology but it can be done so some GoogleFu will sort you out.
 
Caporegime
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What's happening is the ARP table in your switch is getting continuously updated with different information about what port the device with that MAC address is connected to.

You will need to change one of the MAC addresses.
 
Soldato
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MAC addresses are embedded, but it's very simple to override them.

A very quick search indicates that XPEnology does have its MAC set in software. Presumably it's a part of fooling DSM to run on non-Synology hardware.

Googling 'xpenology mac address' turns up guides on how to change the MAC (and linked serial).
 
Soldato
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The conflict has resurfaced but I have not changed anything on the boot usb stick. Here are the contents of both conf files. I let one microserver boot using one conf file and then rename it as grubb, and rename the other conf to grub when I boot thesecond microserver. Any ideas?

-------------------------------------------------------------------
grub.conf

#serial --unit=0 --speed=115200
#terminal serial
default 1
timeout 3
hiddenmenu
fallback 0

title SYNOLOGY_1
root (hd0,0)
kernel /zImage root=/dev/md0 ihd_num=5 netif_num=4 syno_hw_version=DS3612xs
initrd /rd.gz

title SYNOLOGY_2
root (hd0,1)
# cksum /grub_cksum.syno
vender /vender show
# hw_model
kernel /zImage root=/dev/md0 ihd_num=5 netif_num=4 syno_hw_version=DS3612xs
initrd /rd.gz
------------------------------------------------------------
grubb.conf

#serial --unit=0 --speed=115200
#terminal serial
default 1
timeout 3
hiddenmenu
fallback 0

title SYNOLOGY_1
root (hd0,0)
kernel /zImage root=/dev/md0 ihd_num=5 netif_num=4 syno_hw_version=DS3612xs
initrd /rd.gz

title SYNOLOGY_2
root (hd0,1)
# cksum /grub_cksum.syno
# vender /vender show
# hw_model
kernel /zImage root=/dev/md0 ihd_num=5 netif_num=4 syno_hw_version=DS3612xs mac1=00113205

-------------------------------------------------------
 
Associate
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Hubs transmit packets on all interfaces, which is why your ping works fine as at least one of the servers responds.

Switches are smarter and will only transmit on a single interface. If both pc's nics have the same mac address, the switch will quickly become confused and you'll get dropped packets.

As already said, xpenology spoofs the mac address and can be varied in the usb's config file.
 
Soldato
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It's been running fine for the last 3.5 years. The only major change being that we have upgraded to fibre broadband and have a new router. Both microservers have static IP adresses so I can't see that being an issue.
 
Soldato
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I changed the default subnet/dhcp that came with the router to suit my environment.

Though it's probably worth putting the old router back in place to see if it makes any difference.

Edit: Same problem with the old router.
 
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Soldato
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