RE-300-E1ZXR10 Routing Technology—— Basic Routing Principles V1122 ZTE University Data Communication Group ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Objectives • Router definition and function • Basic conception • Working principle of router • IP routing process ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Router definition(1) Router——A kind of computer device used to interconnect network Router must have the following features: Multiple three layer interfaces to interconnect different networks Implement the protocol up to the network layer Have the function of storing 、 forwarding 、 path-finding ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Router functions(2) The core function of router is interconnecting networks and data forwarding. routing ： building route table and refreshing switching ： forwarding packet between networks. Insulate broadcast packets ， define access rule. Connecting different kinds of networks. Rate adapting between networks. ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Objectives • Router definition and function • Basic conception • Working principle of router • IP routing process ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Basic concepts • routed protocol • routing protocol • routing table • metric • connected route • static route • dynamic route • default route • distance • the longest matching principle • Classful / classless routing ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Routing protocol and routed protocol 10.120.2.0 172.16.2.0 E0 S0 Network Destination Exit Interface 172.17.3.0 Protocol Network Connected 10.120.2.0 fei_0/1 RIP 172.16.2.0 e1_1 OSPF 172.17.3.0 e1_2 Routed protocol: IP Routing protocol: RIP, OSPF ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route table • The information that router need to forward data is stored in a table, called ’route table’ • Router check the destination address of the packet,and choose the next hop based on the information in route table. • Route table is stored in RAM ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route table composition Route table composition: • Destination address • Mask • Next hop address (Gateway) • Forwarding physical interface • Source of the information(Owner) • Route priority • metric ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route table composition Example Dest Mask Gw Interface Owner pri metric 172.16.8.0 255.255.255.0 1.1.1.1 fei_0/1.1 static 1 0 172.16.8.0 -- Destination network address 255.255.255.0 -- Destination network mask 1.1.1.1 -- Next hop address fei_0/1.1 -- Route learning interface and forwarding interface static -- how does router learns this entry 1 -- route priority 0 -- Metric ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route table establishing and refreshing How is route established at the beginning? How to maintain the route table after it is established? ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route Types Directly Default route connected route Static route Dynamic route ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Directly connected route 10.0.0.1/24 192.168.0.1/30 172.16.0.1/24 A 192.168.0.2/30 B IPv4 Routing Table: Dest Mask Gw Interface Owner pri metric 10.0.0.0 255.255.255.0 10.0.0.1 fei_0/1 direct 0 0 10.0.0.1 255.255.255.255 10.0.0.1 fei_0/1 address 0 0 192.168.0.0 255.255.255.252 192.168.0.1 e1_1 direct 0 0 192.168.0.1 255.255.255.255 192.168.0.1 e1_1 address 0 0 ZXR10# Directly connected route When network address is configured and the status of the interface is valid, the network configured on this network will appear in the route table and associated with this interface ， the route will change with the status of the interface. ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Static route configuration Stub Network 172.16.1.0 SO 10.0.0.0 B A B Network 172.16.2.2 172.16.2.1 ip route 10.0.0.0 255.0.0.0 172.16.2.2 This is a unidirectional route, there should be an opposite route configured on the counterpart router. ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Default route configuration Example Stub Network 172.16.1.0 SO Network A B B 172.16.2.2 172.16.2.1 ip route 0.0.0.0 0.0.0.0 172.16.2.2 Default route is configured on the egress router in a st ub network. ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Dynamic route OSPF RIP OSPF RIP 1.0.0.0/8 2.0.0.0/8 3.0.0.0/8 Routing protocol is a software process running on the r outer. It will exchange routing information with other ro uters ， studying route information of network not direc tly connected and adjusting the route information when t opology changes. ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route priority Select the route that has the highest priority to the route table 。 RIP OSPF 10.0.0.0/16 fei_1/1 10.0.0.0/16 fei_1/3 10.0.0.0/16 fei_1/3 Notice ： the comparison of Route table route priority must be between identical routes. ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Default route priority Route Route Source Source Default Default priority priority Connected interface 0 Static route 1 External BGP 20 OSPF 110 IS-IS 115 RIP v1, v2 120 Internal BGP 200 Special (For inner process) 255 ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Float static route fei_1/1 e1_2/1.1 DDN Network serial_3/1 PSTN How to configure static route when there are redundant links? ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Float static route fei_1/1 e1_2/1.1 DDN Network serial_3/1 PSTN ZXR10(config)#ip route 10.0.0.0 255.0.0.0 e1_2/1.1 ZXR10(config)#ip route 10.0.0.0 255.0.0.0 serial_3/1 5 ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Longest match principle ZXR10#show ip route IPv4 Routing Table: Dest Mask Gw Interface Owner pri metri c 1.0.0.0 255.0.0.0 1.1.1.1 fei_1/1.1 direct 0 0 1.1.1.1 255.255.255.255 1.1.1.1 fei_1/1.1 address 0 0 2.0.0.0 255.0.0.0 2.1.1.1 fei_1/1.2 direct 0 0 2.1.1.1 255.255.255.255 2.1.1.1 fei_1/1.2 address 0 0 3.0.0.0 255.0.0.0 3.1.1.1 fei_1/1.3 direct 0 0 3.1.1.1 255.255.255.255 3.1.1.1 fei_1/1.3 address 0 0 10.0.0.0 255.0.0.0 1.1.1.1 fei_1/1.1 ospf 110 10 10.1.0.0 255.255.0.0 2.1.1.1 fei_1/1.2 static 1 0 10.1.1.0 255.255.255.0 3.1.1.1 fei_1/1.3 rip 120 5 0.0.0.0 0.0.0.0 1.1.1.1 fei_1/1.1 static 0 0 10.1.1.1? ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Objectives • Router definition and functions • Basic conception • Working principle of router • IP routing process ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Router working principle • Routing function ： Study and maintain the network topology,produce and maintain ro ute table • Forwarding function ： Data transferring and processing procedure(Receiving data on one interface,then choose an appropriate interface to send it out, includin g the work of frame encapsulation and decapsulation) ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route function Study and maintain the network topology mechanism is reg arded as the function of routing.It requires several basic in formation ： • What kind of protocols to route ？ • Is the destination network address in the route table? • Which interface to send out the packet ？ • What is the next hop address ？ ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Forwarding Function Frame checking and cache the Coming packet ＝ interface Associate destination address with Route Maintained by routing protocol the next hop interface ＝ table Create the frame head with the ARP cache Maintained by physical address ＝ （ LAN ） Mapping list （ WAN ） ARP or RARP process Packet encapsulation and Out interface forwarding ＝ ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Route working process summary Add route based on route priority Search entry in route table Based on destination address Routing Routing Routing process Routing process process Route Forwarding process table process Longest match principles Routing protocol study possible route,select the best route based on metric ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Objectives • Router definition and functions • Basic conception • Working principle of router • IP routing process ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Communication in the same network To router1 Network Hub/switch A ┉┉┉ Communication requirement ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Communication process A B Network Hub IP address ： 192.168.1.1 IP address ： 192.168.1.2 MAC address ： MAC address ： 00:20:AF:00:00:01 00:20:AF:00:00:02 No need to consider higher layer protocols Encapsulate IP decapsulate address in IP packet Protocol IP layer packet and send Receiving I IP layer layer to 192.168.1.2 P packet ARP Ethernet Encapsulate MAC Decapsulate Ethernet address in frame MAC frame and send to MAC Receiving M address AC frame 00:20:AF:00:00:02 ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Communication between different network Router Router DDN PPP Network A Network B Ethernet Ethernet Communication requirements ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Communication between different network Network PPP Ethernet Ethernet fei-1/1 e1_2/1.1 e1_2/1.1 fei-1/1 HOST A HOST B No need to consider No need to consider Protocol higher layer protocols higher layer protocols IP IP IP IP IP IP IP layer IP layer IP layer IP layer packet packet packet packet packet packet Ethernet Serial Serial Ethernet Ethernet Ethernet interface interface interface interface MAC PPP MAC frame frame frame Send host router router Receiving A host B PPP packet ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Communication process Get peer IP address Whether in the same YES YES Is the peer MAC Data link layer network address in ARP table? encapsulation with peer NO NO Get peer MAC Address by ARP Send data at physical layer YES Is gateway YES Is the gateway MAC Data link layer configured ？ address in ARP? encapsulation NO NO End Get gateway MAC Send error message address by ARP ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. IP communication process IP communication process basic conception: • IP communication is hop by hop communication • Source IP and destination IP address is unchanged • Every time the packet passed a data link layer,there will be a new encapsulation of the packet • The return path is not related to the forwarding path ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Network protocol layer process X C Y A B X Y Application Application Presentation Presentation Session A B C Session Transport Transport Network Network Network Network Network Data Link Data Link Data Link Data Link Data Link Physical Physical Physical Physical Physical ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Routing process example R1 route table 192.168.4.0 255.255.255.0 192.168.4.1 e1_1/1.1 direct 0 0 192.168.2.0 255.255.255.0 192.168.2.1 fei_1/1 direct 0 0 192.168.1.0 /24 192.168.1.0 255.255.255.0 192.168.4.2 e1_1/1.1 rip fei_1/1 120 1 R2 192.168.6.0 255.255.255.0 192.168.4.2 e1_1/1.1 rip 120 1 e1_2/1.1 e1_1/1.1 192.168.3.0 255.255.255.0 192.168.4.2 e1_1/1.1 rip 120 2 192.168.6.0 /24 192.168.4.0 /24 e1_1/1.1 e1_1/1.1 R3 R1 fei_1/1 fei_1/1 Destination address: 192.168.3.3 192.168.3.0 /24 192.168.2.0 /24 192.168.2.3 A B 192.168.3.3 ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Routing process example R2 route table 192.168.4.0 255.255.255.0 192.168.4.2 e1_1/1.1 direct 0 0 192.168.6.0 255.255.255.0 192.168.6.1 e1_2/1.1 direct 0 0 192.168.1.0 /24 192.168.1.0 255.255.255.0 192.168.1.1 fei_1/1 direct 0 fei_1/1 0 R2 192.168.2.0 255.255.255.0 192.168.4.1 e1_1/1.1 rip 120 1 e1_1/1.1 e1_2/1.1 192.168.3.0 255.255.255.0 192.168.6.2 e1_1/1.1 rip 192.168.4.0 /24 120 1 192.168.6.0 /24 Destination Address: e1_1/1.1 e1_1/1.1 192.168.3.3 R3 R1 fei_1/1 fei_1/1 192.168.2.0 /24 192.168.3.0 /24 192.168.2.3 1.Destination address:192.168.3.3 192.168.3.3 ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Routing process example R3 route table 192.168.3.0 255.255.255.0 192.168.3.1 fei_1/1 direct 0 0 192.168.6.0 255.255.255.0 192.168.6.2 e1_1/1.1 direct 192.168.1.0 /24 0 0 fei_1/1 192.168.1.0 255.255.255.0 192.168.6.1 e1_1/1.1 rip R2 120 1 192.168.4.0 255.255.255.0 192.168.6.1 e1_1/1.1 rip e1_1/1.1 e1_2/1.1 120 1 192.168.4.0 /24 192.168.6.0 192.168.2.0 /24 255.255.255.0 192.168.6.1 e1_1/1.1 rip 120 2 Destination address: e1_1/1.1 e1_1/1.1 192.168.3.3 R3 Return path ？ R1 fei_1/1 fei_1/1 192.168.2.0 /24 192.168.3.0 /24 192.168.2.3 192.168.3.3 ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Review • Definition of router • Router functions • Basic conceptions in routing • IP routing process within the same subnet • IP routing process between different subnet ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited. Questions • What’s the two main functions of router? • How is the route table established? • What is the standard when a router is selecting the route to route table? • When forwarding IP packet, If there are many mat ches, what will router do? • Describe the encapsulation and decapsulation duri ng the process of IP routing . ZTE University univ.zte.com.cn The information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.