5 161
1 1.1 DDT WG DDT WG 1. \DDT" 2. DDT WG DDT WG 1.2 x ( IP) y ( X.25) x y \x overy" x y 1.1 IP X.25 IP IP IPX Appletalk OSI IP \encapsulation" \encapsulation header" \decapsulation" 163
164 1993 WIDE TCP/IP network TCP/IP network IP TCP Data IP TCP Data X.25 IP TCP Data X.25 network 1.1: TCP/IP over X.25 1.3 1. \IP in IP" (ipproto=4) IPng IP (IPv4) IP (IPng) IPv4 IPng \IPng over IPv4" IPng IPv4 [64][65] IP \IPX over IP"[66], \OSI CLNP over IP"[67][68] GRE (Generic Routing Encapsulation)[69][70]
5 165 2. [71] (Mobile Host: MH) MSR (Mobile Support Router) \IP within IP" (ipproto=94) 3. forwarding [72] [73] IDRP AS border gateway [74] AS AS IP [75] \IP over IP" \Internet Encapsulation Protocol"[76] \PPP over TCP" [77] 4. IP option IP IP option 40 1.4 TP-num
166 1993 WIDE 1. TTL 1 MTU MTU MTU [78] 2. QoS QoS (Quality of Service) QoS 3. packet lter 4. ( ) cost/metric 5.
5 167 [76] 6. CPU 7. MTU MTU MTU MTU 8. 9. (Layer Violation)
168 1993 WIDE 10. 1.5 DDT WG 2 \DDT" TP-10 \DDT" \DDT" 3 TP-9 TP-1, TP-2, TP-3, TP-4 TP-5, TP-6, TP-7, TP-8 4 DDT \DDT" \DDT" \DDT" 5 DDT WG '94
2 2.1 DDT Ethernet \DDT" 1 DDT DDT 2.1 \IP over IP" DDT H a H b H a, H b P a, P b V a, V b N v H a, H b 2 N v V a, V b N v N v 2.1 H a H b IP N v H a (\DDT") N v V a V b TCP H b (\DDT") H b 1 DDT \Doki Doki Tunneling" \Delightfully Dangerous Tunneling" 169
170 1993 WIDE Ha Hb Application Application Transport (TCP) DDT pump DDT pump Transport (TCP) Network (IP) Network (IP) Ether DDT DDT Ether Na Pa Va Virtual Network DATA TCP IP (Nv) Vb Pb Nb DATA TCP IP IP Normal Internet 2.1: IP over IP DDT 2.1 H a ( \Network (IP)") DDT (\DDT") IP (\DDT pump") (\Ether") (\N a ") 2.1 P a P b N v H b (\Ether") (\Network (IP)") DDT TCP 2.2 2.2.1 rewall
5 171 Bypass Network Internet G Firewall Gateway Organization Network G Isolated Gateway Isolated Island 2.2: DDT DDT DDT 2.2.2 DDT rewall DDT ( 2.3 )
172 1993 WIDE H Firewall Router GW Global Internet Addres Space DDT Virtual Network Physical Network Private Address Space Ha Hb 2.3: DDT H Firewall Router Imaginary Host Imaginary NAT Ha Communication Real Communication Ha Mapped by NAT Real Host 2.4: NAT NAT (Network Address Translator)[79] DDT NAT rewall NAT NAT NAT DDT ( 2.4 )
5 173 2.2.3 A Secure Virtual Network DDT DDT secure TOS[80] rewall DDT 2.2.4 DDT 2 Ethernet OSI 2.3 BSD DDT DDT 1. 4.3 BSD tahoe BSD Networking Software Release 2 (NET2) 2. 3. 2.3.1 4.3 BSD 4.3BSD 2.5 [81]
174 1993 WIDE trap ) ) ) 2.5: 4.3BSD OSI 7 TCP XX output() XX input() XXintr() XX intrq 2.3.2 2.6 1 ( )
5 175 Socket Layer Protocol Layer tcp_output in_ddt_output in_ddt_input tcp_input ip_output ip_output ipintr ipintr Interface Layer ddt_output IF_output IF_input ddt_input HARDWARE 2.6: DDT BSD ddt output() 4.3 BSD ddt input() 1 484 2 ( ) in ddt output() in ddt input()
176 1993 WIDE 471 2.3.3 DDT MTU next hop MTU next hop MTU MTU 0 next hop MTU \The Path MTU discovery algorithm"[82][83] \IP MTU Discovery options"[84] 2.3.4 An Unnumbered Link DDT N a N b DDT N a subnet N b DDT N a N a subnet N a (1) subnet default (2) CIDR[85] (3) "unnumbered link" (3) \unnumbered link" H a H a P a H b P b (ifcong) P b P b
5 177 Application Daemon TCP IP Ether IF_tun /dev/tun0 Ethernet 2.7: Pnet unnumbered link 4.3BSD tahoe unnumbered link IFF UP o 2.3.5 Pnet DDT Pnet[86] 2.7 Pnet Pnet tunxx /dev/tunxx IP tunxx /dev/tunxx /dev/tunxx tunxx IP ptyxx ttypxx Pnet Pnet DDT
178 1993 WIDE DDT 2.3.4 \unnumbered link" Pnet
3 (TP-9) 3.1 3.1.1 Layer Violation SAP (Service Access Point) System V STREAMS 3.1 IP 1 1 1 1.3 4 179
180 1993 WIDE TOP: Information RFC822 SMTP TCP IP Encryption IP MAC RFC822 SMTP TCP IP MAC Compression Encryption BOTTOM: Device STACK Available Protocols 3.1: \IP" STREAMS 2 3 3.2 ( OSI 7 ) 2 3 \view" view view view 3.3 view
5 181 src dst ATM Information RFC822 SMTP TCP IP Encryption IP Ether FDDI Ether : (2 ) : ( ) 3 3.2: Information RFC822 Application Transport Internet interface SMTP TCP IP Encrypt IP Ether Application Transport Internet interface view-a STACK view-b 3.3: \view"
182 1993 WIDE 3.1.2 (TP-9 ) 2 3 3.2 (TP-1, TP-2, TP-3) (TP-4) 2 3 3.2.1 (TP-1, TP-2, TP-3) 1. (TP-1) (2 TTL ) 2. (TP-2) (2 QoS ) 3. (TP-3) (2 )
5 183 3 Connectionless Connection-Oriented Connectionless Connectionless 2 3 TTL, QoS, ID ( ) TTL, QoS, ID 3 2 1. 2 TTL TTL TTL TTL TTL 2. 2 QoS QoS QoS 3. 2 ( ID ) ID ID TTL, QoS, ID 3 ID Connection-Oriented Connection-Oriented 2
184 1993 WIDE 1. 2 TCP Connectionless 2. QoS ftp port TOS 3. QoS ID QoS ID ID 3.2.2 2 3 : x y x y 1. 2
5 185 2. 3 3 3 (TP-4) 2 3 2 3 : x y x y Ethernet IP IP Ethernet 3 1. 2. 3. cost/metric up/down 2 TP-4
186 1993 WIDE 1. 1-1 x y x y 1-2 \down" 1-3 \down" \down" 2. 3. Distance Vecotr Link State 3.3 TP-5, TP-6, TP-7, TP-8 (TP-5) (TP-6) CPU IP [87] MTU MTU (TP-7) MTU MTU [82][83][84]
5 187 MTU MTU MTU 0 (TP-8)
4 DDT DDT DDT 4.1 { { { / { { { DDT Short Term ( ) 188
5 189 DDT 4.2 DDT DDT DDT 1 3 DDT DDT DDT (Firewall) 1 WIDE
190 1993 WIDE : ISDN DDT 2 3 IP TTL MTU ICMP ICMP ICMP : telnetx ftpmail IP TTL : udprelay DDT DDT DDT
4.3 5 191 / 4.1 2 1. / 2. 1 DDT 2 DDT DDT DDT DDT
192 1993 WIDE 4.4 DDT DDT DDT DDT
5 DDT WG '94 1994 DDT WG { { CIDR skip { { DDT { 3 { 3 IP { 3 { (TP-8) 193
194 1993 WIDE