اريد معرفه اسم الlayer الذي تقوم بهذه الوظيفه
السؤا ل الاول

a)providing a user interface

b)dividing the transmitted bit stream into frames
c)determining which route through the subnet to use
d)data encryption and compression services
e)congestion control
f)controlling access to the shared channel
g)concerning with syntax and cemantics of the information transmitted
h)determining how the initial connection is established and hw it is torn down
السؤال الثاني
ماهو الفرق بين packet switching &circuit switching

ومشكور لكل من يفيد