Figure 8-5: Multiprotocol Routing Site B Site A uniX Ethernet Old IPX SNA Edge Mainframe Server LAn 1 NetWare SPX Router Z Server TCP/ Multiprotocol Router TCP/ The Internet Ethenet Ethernet LAN2自 Lan 3 P Real routers must handle multiple WW Server nternet and transport layer architectures TCP/IP IPX/SPX SNA etc We will only look at TCP/P routing 8-16
8-16 Figure 8-5: Multiprotocol Routing Multiprotocol Router X TCP/ IP TCP/ IP IPX/ SPX SNA WWW Server Edge Router Z Site A Site B Mainframe Internal Router Y Ethernet LAN 1 Ethernet LAN 2 Ethernet Lan 3 The Internet Old NetWare Server UNIX Server Figure 8-5: Multiprotocol Routing Real routers must handle multiple internet and transport layer architectures— TCP/IP, IPX/SPX, SNA, etc. We will only look at TCP/IP routing
I Figure 8-6: Ethernet Switching versus IP Routing Ethernet Switching Switch ,,,,,,,, Destination address is E5-BB-47-21-D3-56 Ethernet switches are arranged in a hierarchy Mitch 2 So there is only one possible path between hosts witch 3 So only one row can match an Ethernet address Finding this row is very simple and fast So Ethernet switching Is inexpensive per frame handled. Switch 1 OIL ElaTIon Switch A144-D5-1F-AA4C B2CD135B-E4-65 5c32D-553B-A94F B6-9 E5BB47-21-356 A144-D5-1F-AA4C Switch 1, Port 2 B2-CD-13-5B-E4-65 Switch 1. Port 7 One correct row 8-17
8-17 Figure 8-6: Ethernet Switching Versus IP Routing A1-44-D5-1F-AA-4C Switch 1, Port 2 B2-CD-13-5B-E4-65 Switch 1, Port 7 Port 7 on Switch 2 to Port 4 on Switch 3 Port 5 on Switch 1 to Port 3 on Switch 2 Switch 2 Switch 1 Switching Table Switch 1 Port Station 2 A1-44-D5-1F-AA-4C 7 B2-CD-13-5B-E4-65 5 C3-2D-55-3B-A9-4F 5 D4-47-55-C4-B6-9F 5 E5-BB-47-21-D3-56 Ethernet Switching Destination address is E5-BB-47-21-D3-56. Ethernet switches are arranged in a hierarchy. So there is only one possible path between hosts. So only one row can match an Ethernet address. Finding this row is very simple and fast. So Ethernet switching is inexpensive per frame handled. One Correct Row
Figure 8-6: Ethernet Switching Versus IP Routing Routing Interface IP Routing Router B Packet to 60. 3.47. 129 Interface 2 Routing Table for Router A Network 60.xxX Matches IP Address Next-Hop Route Range Metric Router Router c _1603Xx Network 2128.171x 360.347X 9286 BBCB 60.3XX 10.5.3X Host 5128.171.17.X2 Local 60.347.X Because of multiple alternative routes in router meshes routers may have several rows that match an IP address Routers must find all matches and then select the best one This is slow and therefore expensive compared to switching 8-18
8-18 Figure 8-6: Ethernet Switching Versus IP Routing Network 60.x.x.x Packet to 60.3.47.129 Router B Router C Interface 1 Interface 2 Network 60.x.x.x IP Routing Network 60.3.x.x Route 1 2 3 4 5 6 IP Address Range 60.3.x.x 128.171.x.x 60.3.47.x 10.5.3.x 128.171.17.x 10.4.3.x Metric 9 2 8 6 2 2 Router A Routing Table for Router A Host 60.3.45.129 Next-Hop Router B B C B Local C Routing Matches Host 60.3.47.x Because of multiple alternative routes in router meshes, routers may have several rows that match an IP address. Routers must find All matches and then select the BEST ONE. This is slow and therefore expensive compared to switching
Figure 8-7: The Routing Process Routing Processing an individual packet and passing it on its way is called routing Router ports are called interfaces Packet arrives in one interface The router sends the packet out another interface 8-19
8-19 Figure 8-7: The Routing Process • Routing – Processing an individual packet and passing it on its way is called routing • Router ports are called interfaces • Packet arrives in one interface • The router sends the packet out another interface
Figure 8-7: The Routing Process The routing table Each router has a routing table that it uses to make routing decisions Routing table rows Each row represents a route for a range of IP addresses--often a network or subnet All packets with addresses in this range are routed according to that row Route IP Address Range Metric Next-Hop Governed by the route Router 60.3XX 9 B 8-20
8-20 Figure 8-7: The Routing Process • The Routing Table – Each router has a routing table that it uses to make routing decisions – Routing Table Rows • Each row represents a route for a RANGE of IP addresses—often a network or subnet • All packets with addresses in this range are routed according to that row Route IP Address Range Governed by the route Metric Next-Hop Router 1 60.3.x.x 9 B