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ingress tagged traffic on unmanaged switch
Hi guys,
I'm sure this has been asked but I'm not able to find a relevent discussion. Simpyl I'd like to know how does the netgear's unmanged switchports handle ingress tagged traffic ?
Do the frames get discarded ?
If yes, based on what criteria ? Frame size,ethertype ??
If it forwards it on, why and again based on what criteria ?
Hope to get some clarifications pls
Hi eyesofra,
I inquired your concern to a higher tier of NETGEAR Support. With regard to your questions, it depends on the ASIC (Application-Specific Integrated Circuit) of the switch, and the switch itself. New switches (with E such as GS108Ev3) will likely pass through (based on MAC table). On older, non-E switches, it would fail CRC and drop the packet. E-switches without VLANs may still be aware of VLANs and be able to pass them through.
However, it is advisable that you should not implement an 802.1Q unaware switch in network wherein you have expectation of persevering 802.1Q traffic. There is reason for Plus switches, this would be one of them.Regards,
DaneA
NETGEAR Community Team
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Hi eyesofra,
Welcome to the community! :)
Let me share the links below that I found online and it might help:
Pushing VLAN Tags Through Unmanaged Switches
How does switch treat ingress tagged packet?
Will VLAN tags pass through a basic, simple switch?
Regards,
DaneA
NETGEAR Community Team
Hi Dane,
Thanks for those links. Very helpful links and I think I've been through some in the past when I was looking it up.
I quote a reply to the question from the last link you provided.
The reason being that it depends on your Netgears firmware and how it deals with unknown situations. There are two problems it will encounter - firstly the 802.1q tagged packets will have a non-standard ethertype specified in the frame which it won't recognise. At this point it'll either drop the frame as damaged or pass it on regardless.
Secondly, 802.1q adds a few bytes to the frame, in the case of large frames it'll push them over the 1500 byte MTU. Again, the Netgear will either forward them or drop them depending on how they've written the firmware.
What this person is saying is very accurate indeed. It's gonna be either one of the 2 cases. Now which one of this applies to the typical netgear prosafe unmanaged switch ? Does it :
1) Look at the ethertype, and drops it cause it doesn't recognize 0x8100 (ethertype for tagged)
2) Look at the frame size and drop it if it's above 1518 (normal size for untagged frames). If this case, what sort of switching would does the switches do ? cut-through/store/forward ?
Hi eyesofra,
As far as I know, Netgear unmanaged switches does store-and-forward switching.
Let say for example, there is an unmanaged switch connected to a managed switch. On a managed switch, there are access ports and trunk ports configured. The unmanaged switch is connected to the access port of the managed switch. The VLAN traffic that exits from the access ports of the managed switch is stripped of any VLAN tags and becomes regular ethernet traffic. The regular ethernet traffic gets 802.1Q tagged by the time it enters the access ports of the managed switch. With regard to this, everything will work fine since the unmanaged switch is connected to the access port. As well as anything that is cascaded to the access port of the managed switch will have regular ethernet traffic.
Kindly answer my questions:
a. Have you tried to connect a NETGEAR unmanaged switch to a trunk/tagged port? If yes, what is the exact model of it.
b. What have you observed when you have connected a NETGEAR unmanaged switch to a trunk/tagged port?
Note: I am open to corrections.
Regards,
DaneA
NETGEAR Community Team
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