IP Routing Static Routing The Router Router Interface

The Router • Router Interface is a physical connector that enables a router to

Routing Table • Routing table should contain at least 2 items – Destination address

Routing Table Router 3#show ip route Codes: C - connected, S - static, I

Routing order 1. 2. 3. 4. Check for a connected network Search for a

The router • As a packet travels from one networking device to another –

Router Path – step 1 • PC 1 Wants to send something to PC

Router Path – step 2 Step 2 - R 1 receives Ethernet frame. 8/14

Router Path – step 2 – Step 2 - R 1 receives Ethernet frame.

Router Path – step 3 Step 3 - Packet arrives at R 2 §

Router Path – step 4 Step 4 - Packet arrives at R 3 §

Demo – packet tracer 12/14 Groep T Leuven – Information department 2003 -2004 -

Case studies • • • Summary routes Default routes Alternative routes Floating static Load

Exercise • Configure the routing that all traffic goes clock wise 10. 2. 0.

Slides: 14

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IP Routing Static Routing

The Router • Router Interface is a physical connector that enables a router to send or receive packets • Each interface connects to a separate network • Consist of socket or jack found on the outside of a router • Types of router interfaces: – -Ethernet – -Fastethernet – -Serial – -DSL – -ISDN – -Cable 2/14 Groep T Leuven – Information department 2003 -2004 - Information management 2

Routing Table • Routing table should contain at least 2 items – Destination address – Pointer to the destination 3/14 Groep T Leuven – Information department Network 10. 1. 1. 0 missingmanagement ! 2003 -2004 is- Information 3

Routing Table Router 3#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N 1 - OSPF NSSA external type 1, N 2 - OSPF NSSA external type 2 E 1 - OSPF external type 1, E 2 - OSPF external type 2, E - EGP i - IS-IS, L 1 - IS-IS level-1, L 2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is not set 10. 0/24 is subnetted, 7 subnets S 10. 1. 1. 0 [1/0] via 10. 1. 4. 1 S 10. 1. 2. 0 [1/0] via 10. 1. 4. 1 S 10. 1. 3. 0 [1/0] via 10. 1. 4. 1 C 10. 1. 4. 0 is directly connected, Serial 2/0 C 10. 1. 5. 0 is directly connected, Fast. Ethernet 0/0 C 10. 1. 6. 0 is directly connected, Serial 3/0 S 10. 1. 7. 0 [1/0] via 10. 1. 6. 2 Leuven – Information department 2003 -2004 - Information management 4/14 Groep TRouter 3# 4

Routing order 1. 2. 3. 4. Check for a connected network Search for a matching host route Search for a matching network route Search for a default gateway (last resort) 5/14 Groep T Leuven – Information department 2003 -2004 - Information management 5

The router • As a packet travels from one networking device to another – -The Source and Destination IP addresses NEVER change – -The Source & Destination MAC addresses CHANGE as packet is forwarded from one router to the next. – -TTL field decrement by one until a value of zero is reached at which point router discards packet (prevents packets from endlessly traversing the network) 6/14 Groep T Leuven – Information department 2003 -2004 - Information management 6

Router Path – step 1 • PC 1 Wants to send something to PC 2 here is part of what happens – Step 1 - PC 1 encapsulates packet into a frame. Frame contains R 1’s destination MAC address 7/14 Groep T Leuven – Information department 2003 -2004 - Information management 7

Router Path – step 2 Step 2 - R 1 receives Ethernet frame. 8/14 Groep T Leuven – Information department 2003 -2004 - Information management 8

Router Path – step 2 – Step 2 - R 1 receives Ethernet frame. § R 1 sees that destination MAC address matches its own MAC. § R 1 then strips off Ethernet frame. § R 1 Examines destination IP. § R 1 consults routing table looking for destination IP. § After finding destination IP in routing table, R 1 now looks up next hop IP address. § R 1 re-encapsulates IP packet with a new Ethernet frame. § R 1 forwards Ethernet packet out Fa 0/1 interface. 9/14 Groep T Leuven – Information department 2003 -2004 - Information management 9

Router Path – step 3 Step 3 - Packet arrives at R 2 § R 2 receives Ethernet frame § R 2 sees that destination MAC address matches its own MAC § R 2 then strips off Ethernet frame § R 2 Examines destination IP § R 2 consults routing table looking for destination IP § After finding destination IP in routing table, R 2 now looks up next hop IP address § R 2 re-encapsulates IP packet with a new data link frame § R 2 forwards Ethernet packet out S 0/0 interface 10/14 Groep T Leuven – Information department 2003 -2004 - Information management 10

Router Path – step 4 Step 4 - Packet arrives at R 3 § R 3 receives PPP frame § R 3 then strips off PPP frame § R 3 Examines destination IP § R 3 consults routing table looking for destination IP § After finding destination IP in routing table, R 3 is directly connected to destination via its fast Ethernet interface § R 3 re-encapsulates IP packet with a new Ethernet frame § R 3 forwards Ethernet packet out Fa 0/0 interface Step 5 - IP packet arrives at PC 2. § Frame is decapsulated & processed by upper layer protocols. 11/14 Groep T Leuven – Information department 2003 -2004 - Information management 11

Demo – packet tracer 12/14 Groep T Leuven – Information department 2003 -2004 - Information management 12

Case studies • • • Summary routes Default routes Alternative routes Floating static Load sharing Trouble shooting static routes 13/14 Groep T Leuven – Information department 2003 -2004 - Information management 13

Exercise • Configure the routing that all traffic goes clock wise 10. 2. 0. 0/24 10. 5. 0. 0/24. 1 64 kbps . 2 10. 1. 0. 0/24 16 kbps . 1 . 2. 1 10. 7. 0. 0/24 14/14 Groep T Leuven – Information department . 1 . 2 128 kbps 10. 6. 0. 0/24 10. 4. 0. 0/24. 1 . 2. 1 10. 3. 0. 0/24 . 2 2003 -2004 - Information management 14