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squircle
join:2009-06-23
OTWAON10

squircle to dsiemon

Member

to dsiemon

Re: [Internet] Per packet overhead on Bell's VDSL? ATM based?

Well the advantage of VDSL2 is that it is much closer to being end-to-end ethernet than ADSL. There's no ATM/AAL5 to worry about (i.e. your 1500 byte packets aren't being chopped into 31 (and a bit) ATM cells), removing the layer that has historically made ADSL connections "lower than advertised."

If you're looking for delay products and such, your best starting point is your line stats on your Cellpipe. If there isn't any upstream/downstream delay, it means there's no interleaving and the WAN link should behave similarly to an ethernet network (VDSL2 even supports VLANs natively). If there is interleaving, that's when the calculations about upstream/downstream delays and such come into effect.

Basically, your VDSL2 modem differs from your ADSL modem in that an ADSL modem is an ethernet to ATM bridge, whereas a VDSL2 modem is an ethernet to ethernet bridge.

QuantumPimp
join:2012-02-19

1 edit

QuantumPimp

Member

IEEE 802.3ah has defined a specific Ethernet TPS-TC using the 64/65-octet encapsulation for Ethernet applications without underlying ATM.

I have no idea how 64/65-octet encapsulation works.