Basics of Dynamic Routing
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Basics of Dynamic Routing. Presented by Aaron Jarvis Network Engineer. Agenda. Introduction to Dynamic Routing Choosing the Right Protocol Configuring Dynamic Routing How the ITaP Production Data Network uses dynamic routing. Agenda. Introduction to Dynamic Routing

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Basics of dynamic routing

Basics of Dynamic Routing

Presented by Aaron Jarvis

Network Engineer


Agenda

Agenda

Introduction to Dynamic Routing

Choosing the Right Protocol

Configuring Dynamic Routing

How the ITaP Production Data Network uses dynamic routing


Agenda1

Agenda

Introduction to Dynamic Routing

Choosing the Right Protocol

Configuring Dynamic Routing

How the ITaP Production Data Network uses dynamic routing


Introduction to dynamic routing

Network

  • What is routing?

    • How data is forwarded between subnets

    • Network Layer or Layer 3 in the OSI Model

    • Provides end-to-end reachability

Data Link

Introduction to Dynamic Routing

Physical


Introduction to dynamic routing1

  • How are routing decisions made?

    • Forwarded based on the destination IP address

    • Router builds/maintains a routing table

      • Current view of the network

      • Populated either dynamically or manually

Introduction to Dynamic Routing

router#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - 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 192.5.40.54 to network 0.0.0.0

69.0.0.0/19 is subnetted, 1 subnets

O E2 69.51.160.0 [110/1] via 192.5.40.54, 6d21h, Port-channel61

O E2 199.233.104.0/24 [110/1] via 192.5.40.54, 3w4d, Port-channel61

192.5.40.0/24 is variably subnetted, 19 subnets, 4 masks

D 192.5.40.238/32 [90/131328] via 192.31.0.13, 2d16h, Vlan4094

[90/131328] via 192.31.0.113, 2d16h, Vlan4084

O IA 192.5.40.225/32 [110/2] via 192.5.40.54, 3w4d, Port-channel61

O IA 192.5.40.227/32 [110/4] via 192.5.40.54, 3w4d, Port-channel61

C 192.5.40.240/28 is directly connected, Vlan898

D 192.5.40.168/29 [90/3072] via 192.31.0.113, 7w0d, Vlan4084

[90/3072] via 192.31.0.13, 7w0d, Vlan4094

Snip……


Agenda2

Agenda

Introduction to Dynamic Routing

Choosing the Right Protocol

Configuring Dynamic Routing

How the ITaP Production Data Network uses dynamic routing


Choosing the right protocol

  • Interior Routing Protocols

    • Used within an autonomous system

    • Used within an area of administrative control

  • Exterior Routing Protocols

    • Used between autonomous systems

    • Used to peer with networks in which you have no administrative control

Choosing the Right Protocol


Choosing the right protocol1

  • Interior Routing Protocols

    • Static

    • RIP

    • OSPF

    • EIGRP

    • ISIS

  • Exterior Routing Protocols

    • BGP

  • NOTE: This is not an exhaustive list of protocols available but merely a list of those commonly used.

Choosing the Right Protocol


Choosing the right protocol2

  • Static Routing

    • May be suitable on small networks

    • Administration intensive as changes have to be made on each router

    • Commonly used for default routing

      • 0.0.0.0/0  Next Hop Router

Choosing the Right Protocol


Choosing the right protocol3

  • Dynamic Routing Protocol Types

    • Distance Vector

      • Routing Information Protocol(RIP)

      • Interior Gateway Routing Protocol(IGRP)

      • Enhanced Interior Gateway Routing Protocol(EIGRP)

    • Link State

      • Open Shortest Path First(OSPF)

      • Intermediate System to Intermediate System(ISIS)

    • Path Vector

      • Border Gateway Protocol(BGP)

Choosing the Right Protocol


Choosing the right protocol4

  • Routing Information Protocol(RIP)

    • RFC 1058(RIPv1), 1988

      • Classful, no support for VLSM

      • No support for authentication

    • RFC 2453(RIPv2), 1998

      • Classless, support for CIDR

      • Support for authentication

    • Uses hop count as routing metric

    • Slow to converge

    • Not very scalable

      • Limited to 15 hops

Choosing the Right Protocol


Choosing the right protocol5

  • Interior Gateway Routing Protocol(IGRP)

    • Invented by Cisco to overcome limitations of RIP

    • Allows for hop count up to 255

    • Allows for multiple route metrics

      • Bandwidth

      • Delay

      • Load

      • MTU

      • Reliability

    • Classful, no support for VLSM

Choosing the Right Protocol


Choosing the right protocol6

  • Enhanced Interior Gateway Routing Protocol(EIGRP)

    • Replaced IGRP

    • Maintains a Topology table

      • Successors, feasible successors

    • Allows for multiple route metrics

    • Classless, support for CIDR

    • Very fast to converge

    • Maintains neighbor relationships

    • Diffusing Update Algorithm(DUAL)

    • Not as CPU intensive as OSPF

Choosing the Right Protocol


Choosing the right protocol7

  • Open Shortest Path First(OSPF)

    • RFC 2328(OSPFv2), 1998

    • Maintains neighbor relationships

    • Concept of Areas

      • Different areas can be used to control flooding of routing information

    • Classless, supports VLSM

    • Fast to converge

    • CPU Intensive Dijkstra Algorithm

    • Designing can be complicated

Choosing the Right Protocol


Choosing the right protocol8

  • Intermediate System to Intermediate System(ISIS)

    • RFC 1142, 1990

    • Dijkstra Algorithm

    • Mainly used by large service providers

    • Does not use IP to carry routing information

      • Uses ISO addresses

    • Level Concept

      • Level 1 or Intra Area

      • Level 2 or Inter Area

      • Level 1/2 or Both

    • Classless, supports VLSM

Choosing the Right Protocol


Choosing the right protocol9

  • Border Gateway Protocol(BGP)

    • RFC 4271(BGPv4), 2006

    • Peers manually defined

    • Used typically for multi-homing to ISP(s)

    • Very scalable

    • Makes decisions based upon AS Path

    • Lots of policy options

    • Very granular control

Choosing the Right Protocol


Agenda3

Agenda

Introduction to Dynamic Routing

Choosing the Right Protocol

Configuring Dynamic Routing

How the ITaP Production Data Network uses dynamic routing


Configuring dynamic routing

  • How to configure dynamic routing?

    • Choose a protocol that meets your needs

    • Each vendor has specific commands but should have a configuration guide available to assist

    • Plan well to ensure a functional network

      • Create a diagram

      • Consider high availability technologies

        • HSRP

        • VRRP

Configuring Dynamic Routing


Configuring dynamic routing1

  • Best Practices

    • Only enable a routing protocol for interfaces you intend on using

      • If compromised can cause a lot of problems

    • Enable authentication(if available)

      • Use authentication to ensure that the remote routers are valid peers

Configuring Dynamic Routing


Configuring dynamic routing2

  • Best Practices Cont…

    • Control Network Advertisements

      • Only allow networks to be advertised that should be

    • Private Address Space

      • Use only within your organization

    • Private AS Numbers

      • Strip before sending to ISP

Configuring Dynamic Routing


Agenda4

Agenda

Introduction to Dynamic Routing

Choosing the Right Protocol

Configuring Dynamic Routing

How the ITaP Production Data Network uses dynamic routing


How the itap production network uses dynamic routing

  • Routing Protocols Used

    • Interior

      • EIGRP

      • OSPF

      • Static

    • Exterior

      • BGP

How the ITaP Production Network Uses Dynamic Routing


How the itap production network uses dynamic routing1

  • Whiteboard Drawing

How the ITaP Production Network Uses Dynamic Routing


Basics of dynamic routing

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