, - . .
. , ( , , - legacy), , . Internet, , EGP BGP. , , .
IP, CONS CLNS OSI, IPX, AppleTalk, DECnet, Banyan VINES, Xerox XNS.
IP RIP, IPX RIP, NLSP, OSPF, IS-IS OSI, EGP, BGP, VINES RTP, AppleTalk RTMP.
. - , Ethernet, Token Ring, FDDI, Fast Ethernet, Gigabit Ethernet, 100VG-AnyLAN .
- , , .
(serial lines) RS-232, RS-449/422, V.35 ( 2-6 /), HSSI, 52 /, 1/1, / BRI PRI ISDN. , .
.25, frame relay, ISDN , , .
. , , frame relay, /3, SDH . , : , , . . , - , , .
- . - , 5 20-30 .
, .
3- , .