Code : STM#520-1 Samsung Electronics Co., Ltd. OfficeServ7400 Router Operation Distribution EnglishED01

© Samsung Electronics Co., Ltd. 2 Objectives After successful completion of the course the trainees should be able to execute the following activities.

© Samsung Electronics Co., Ltd. 3 Contents Layer 3 Routing Overview Layer 3 Routing Overview Routing Configuration Routing Configuration

© Samsung Electronics Co., Ltd. 4 Layer 3 Routing Overview Layer 3 Routing Overview

© Samsung Electronics Co., Ltd. 5 Overview Introduction Static routing is fine if the network is small, there is a single connection point to other networks, and there are no redundant routes. If any of these conditions is false, dynamic routing is normally used. Look at the dynamic routing protocols used by routers to communicate with each other.

© Samsung Electronics Co., Ltd. 6 IGP and EGP IGP (Interior Gateway Protocol) Routing protocol to communicate between the routers in each AS. RIP (Routing Information Protocol) OSPF (Open Shortest Path First) EGP (Exterior Gateway Protocol) Routing protocols that are used between the routers in different ASs. BGP (Border Gateway Protocol) ASAS IGP IGP EGP

© Samsung Electronics Co., Ltd. 7 IGP and EGP Popular routing protocols

© Samsung Electronics Co., Ltd. 8 Autonomous systems Interior routing Exterior routing

© Samsung Electronics Co., Ltd. 9 Routing information Example R : How the route was learned (RIP) : Destination logical network or subnet 120 : Administrative distance /2 : Metric Value 00:00:23 : Age of entry eth0 : Outgoing interface Metric If there are multiple paths within the AS from a router to a network, the router selects the path with the smallest hop count. RIP : Hop Counts OSPF : Bandwidth, Cost, …. R [120/2] via , 00:00:23, eth0

© Samsung Electronics Co., Ltd. 10 Routing information Administrative distance

© Samsung Electronics Co., Ltd. 11 Static Route (example) / / / / / / / / /24 B A C D E e1 e0 s0 e0 e1 Router B ip route ip route ip route

© Samsung Electronics Co., Ltd. 12 RIP Use UDP datagram UDP datagram Format Metric: Hop Counts Hop Count’s limit : 15 IP headerUDP headerRIP message 20 bytes8 bytes

© Samsung Electronics Co., Ltd. 13 RIP is based on distance vector routing, which uses the Bellman-Ford algorithm for calculating the routing tables. Distance Vector Routing each router periodically shares its knowledge about the entire internet with neighbors the operational principles of this algorithm Sharing knowledge about the entire autonomous system Sharing only with neighbors Sharing at regular intervals (ex, every 30 seconds) Distance Vector Routing Table

© Samsung Electronics Co., Ltd. 14 RIP RIPv1 message format Command(1-6)Version(1)(must be zero) Address family(2)(must be zero) 32-bit IP address (must be zero) Metric(1-16) (up to 24 more routes, with same format as previous 20 bytes) Command : request (1) or response (2) Version of RIPv1 : 1 Address : destination network address Distance : defining the hop count from the advertising router to the destination network

© Samsung Electronics Co., Ltd. 15 RIP RIPv2 message format command(1-6)Version(2)routing domain address family(2)Routing tag 32-bit IP address 32-bit subnet mask 32-bit next-hop IP address metric(1-16) (up to 24 more roues, with same format as previous 20 bytes) 20bytes Route Tag : carrying information such as the autonomous system number Subnet mask : carrying the subnet mask Next-hop address : showing the next hop

© Samsung Electronics Co., Ltd. 16 RIP Timers in RIP Periodic timer : controlling the advertisements of regular update messages Expiration timer : governing the validity of a route The garbage collection timer : advertising the failure of a route Periodic timer Controlling the advertising of regular update messages Using random number between 25 to 35 seconds

© Samsung Electronics Co., Ltd. 17 RIP Expiration timer In normal situation, the new update for a route occurs every 30 seconds But, if there is a problem on an Internet and no update is received within the allotted 180 seconds, the route is considered expired and the hop count of the route is set to 16. Each router has its own expiration timer. Garbage Collection Timer When the information about a route becomes invalid, the router continues to advertise the route with a metric value of 16 and the garbage collection timer is set to 120 sec for that route When the count reaches zero, the route is purged from the table.

© Samsung Electronics Co., Ltd. 18 RIP Timer Example A routing table has 20 entries. It does not receive information about five routes for 200 seconds. How many timers are running at this time? The timers are listed below: Periodic timer: 1 Expiration timer: = 15 Garbage collection timer: 5

© Samsung Electronics Co., Ltd. 19 RIP Routing update RIPv1(Broadcast) RIPv2(Multicast)

© Samsung Electronics Co., Ltd. 20 RIP Routing update

© Samsung Electronics Co., Ltd. 21 RIP RIP (Example) / / / / / / / / /24 B A C D E e1 e0 s0 e0 e1 Router A router rip network /24 network /24 Router B router rip network /24 network /24 Router D router rip network /24 network /24 Router E router rip network /24 Router C router rip network /24 network /24

© Samsung Electronics Co., Ltd. 22 OSPF Characteristics In a distance-vector protocol, each router sends and receives the messages which contain a vector of distances. (hop counts) In a link-state protocol, each router actively tests the status of its link to each of its neighbors, sends this info. to its other neighbors, which then propagate it throughout the AS. From a practical perspective, the important difference is that a link- state protocol will always converge faster than a distance vector protocol. Area 0 Area 1Area n Backbone router Area border router Internal router

© Samsung Electronics Co., Ltd. 23 OSPF Features that make OSPF superior to RIP OSPF can calculate a separate set of routes for each IP type-of- service. Each interface is assigned a dimensionless cost.(throughput, RTT, etc.) Load balancing: When several equal-cost routes to a destination, OSPF distributes traffic equally among the routes. OSPF supports subnets. Point-to-point links bet’n routers do not need an IP addr. at each end. A simple authentication scheme can be used. OSPF uses multicasting instead of broadcasting.

© Samsung Electronics Co., Ltd. 24 OSPF RIP vs OSPF Function/FeatureRIPv1RIPv2OSPF Standard numberRFC 1058RFC 1723RFC 2178 Link-state protocolNo Yes Large range of metricsHop count(16 = infinity) Yes, based on 1-65,535 Update policy Routing table every 30 seconds Routing table every 30 seconds When link state change Or every 30 minutes Update addressBroadcastBroadcast, multicastmulticast Dead interval300 seconds total Variable settings Supports authenticationNoYes Convergence time Media delay + Dead interval Variable(based on Number of routers * DI) Variable(based on Number of router * DI) Variable-length subnetsNOYes Type of service(TOS)NO Yes Network diameter15 hops 65,355 possible

© Samsung Electronics Co., Ltd. 25 OSPF OSPF Message Format

© Samsung Electronics Co., Ltd. 26 OSPF Hierarchical Routing Consists of areas and autonomous systems Minimize routing update traffic Area 0 Area 1Area 2 Autonomous System

© Samsung Electronics Co., Ltd. 27 OSPF The Backbone and Virtual Links Backbone center of communication Virtual link provide path to backbone Avoid configuring virtual link if possible Area 0 Area 1 Area 2 Area 3

© Samsung Electronics Co., Ltd. 28 OSPF Link-State DB & Advertisement Link-State DB represents the network topology shared with OSPF routers in same area LSA (Link-State Advertisement) sourced by router connected to link flooded by all other routers in area transmitted at each link-state change LSA

© Samsung Electronics Co., Ltd. 29 OSPF Link-State Advertisement Operation LSA LSA received Is entry in topological database reset timer for entry add to database flood LSA run SPF to caculate new table Y N

© Samsung Electronics Co., Ltd. 30 OSPF Type of Link-State Packets router network summary external ABRASBR external AS O - OSPF derived intra-area (router) IA - inter-area (summary) E1 - type 1 external E2 - type 2 external OSPF routing table

© Samsung Electronics Co., Ltd. 31 OSPF Configuration Example / / / / / / / /24 B A C D E e1 e0 s0 e0 e1 Router B router ospf network /24 area0 network /24 area1 Router C router ospf network /24 area0 network /24 area2 Router D router ospf network /24 area2 network /24 area2 Area 1 Area 0 Area 2

© Samsung Electronics Co., Ltd. 32 OSPF Virtual Link Example / / / / / / / / /24 B A C D E e1 e0 s0 e0 e1 Area 1 Area 0 Area 2 Area 3 Router C router ospf 100 network area 0 network area 2 area 2 virtual-link Router D router ospf 100 network area 2 network area 3 area 2 virtual-link

© Samsung Electronics Co., Ltd. 33 Configuration Configuration

© Samsung Electronics Co., Ltd. 34 Configure Static Route Configuration Configure routing entry using static route. We can use Default GW option of Interface Network ip route or ip route /

© Samsung Electronics Co., Ltd. 35 Configure Static Route Static Route command & status For static route using Input Configuration Command Current Configuration Status add static route

© Samsung Electronics Co., Ltd. 36 Configure RIP Configuration /24 OS7400 # /24 OS7400 # / /24 PC # OS7400 #3 OS7400 #1 configuration router rip version 2 (or version 1) network /24 redistribute connected OS7400 #2 configuration router rip version 2 (or version 1) network /24 network /24 redistribute connected OS7400 #3 configuration router rip version 2 (or version 1) network /24 redistribute connected OS7400 #1 configuration router rip version 2 (or version 1) network /24 redistribute connected OS7400 #2 configuration router rip version 2 (or version 1) network /24 network /24 redistribute connected OS7400 #3 configuration router rip version 2 (or version 1) network /24 redistribute connected OS7400 #2 Routing Table R>* /8 [120/2] via , eth0, 00:01:23 R>* /8 [120/2] via , eth1, 00:02:02 C>* /8 is directly connected, lo C>* /24 is directly connected, eth1 C>* /24 is directly connected, eth0 OS7400 #3 Routing Table R>* /8 [120/3] via , eth0, 00:03:09 C>* /24 is directly connected, eth1 C>* /8 is directly connected, lo C>* /24 is directly connected, eth0 R>* /24 [120/2] via , eth0, 00:01:08 OS7400 #2 Routing Table R>* /8 [120/2] via , eth0, 00:01:23 R>* /8 [120/2] via , eth1, 00:02:02 C>* /8 is directly connected, lo C>* /24 is directly connected, eth1 C>* /24 is directly connected, eth0 OS7400 #3 Routing Table R>* /8 [120/3] via , eth0, 00:03:09 C>* /24 is directly connected, eth1 C>* /8 is directly connected, lo C>* /24 is directly connected, eth0 R>* /24 [120/2] via , eth0, 00:01:08

© Samsung Electronics Co., Ltd. 37 Configure RIP RIP command and status Example) Configuration of OS7400 #3 -. RIP version 2 -. Redistribute Connected route (address of Network Interface)

© Samsung Electronics Co., Ltd. 38 Configure OSPF Configuration PC # /24 OS7400 # /24OS7400 # / /24 PC # OS7400 #3 OS7400 #1 configuration router ospf network /24 area 0 redistribute connected OS7400 #2 configuration router ospf network /24 area 0 network /24 area 0 redistribute connected OS7400 #3 configuration router ospf network /24 area 0 redistribute connected OS7400 #1 configuration router ospf network /24 area 0 redistribute connected OS7400 #2 configuration router ospf network /24 area 0 network /24 area 0 redistribute connected OS7400 #3 configuration router ospf network /24 area 0 redistribute connected OS7400 #2 Routing Table O>* /24 [110/20] via , eth0, 00:04:21 O>* /24 [110/20] via , eth1, 00:02:22 C>* /8 is directly connected, lo O /24 [110/10] is directly connected, eth1, 00:04:22 C>* /24 is directly connected, eth1 O /24 [110/10] is directly connected, eth0, 00:04:22 C>* /24 is directly connected, eth0 OS7400 #3Routing Table O>* /24 [110/20] via , eth0, 00:02:31 C>* /24 is directly connected, eth1 C>* /8 is directly connected, lo O /24 [110/10] is directly connected, eth0, 00:03:10 C>* /24 is directly connected, eth0 O>* /24 [110/74] via , eth0, 00:02:32 OS7400 #2 Routing Table O>* /24 [110/20] via , eth0, 00:04:21 O>* /24 [110/20] via , eth1, 00:02:22 C>* /8 is directly connected, lo O /24 [110/10] is directly connected, eth1, 00:04:22 C>* /24 is directly connected, eth1 O /24 [110/10] is directly connected, eth0, 00:04:22 C>* /24 is directly connected, eth0 OS7400 #3Routing Table O>* /24 [110/20] via , eth0, 00:02:31 C>* /24 is directly connected, eth1 C>* /8 is directly connected, lo O /24 [110/10] is directly connected, eth0, 00:03:10 C>* /24 is directly connected, eth0 O>* /24 [110/74] via , eth0, 00:02:32

© Samsung Electronics Co., Ltd. 39 Configure OSPF OSPF command and status Example) Configuration of OS7400 #3 -. OSPF area 0 -. Redistribute connected route (address of Network Interface)

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