Do any of the ITU DSL standards limit the maximum MTU that can be supported?
I know that RFC2516 (PPPoE) limits the MTU to 1492 bytes; however when PPPoE is not used this limit should not exist.
The PPP, L2TP and ATM AAL5 standards all have 16-bit length fields allowing for packets up 64k in length.
I have frequently seen wholesale carrier hand offs for ADSL and G.SHDSL with limits on MTU supported anywhere between 1460 and 1500 bytes; however I am not aware of any carriers advertising capabilities above 1500 bytes.
Is there any standards based limitation on DSL connections restricting the packet sizes on DSL lines, or is it simply arbitrary limits from vendors and carriers that are restricting the availability of large frame support in the market?