Networking and Internetworking Devices

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Networking and Internetworking Devices

• Repeaters
• Bridges
• Routers
• Gateways
• Routing Algorithms

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Homework

• p.641 prob 1-18

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(No Transcript)
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Connecting Devices and the OSI Model
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Repeater and OSI Model
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A Repeater
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Function of a Repeater
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Bridge and the OSI Model
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Bridges

• Reduces Collision Domain / Congestion
• Simple
• Addresses manually entered
• Multiport
• Transparent
• Builds routing table itself
• Updates table based on source addresses

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A Bridge
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Function of a Bridge
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Router and the OSI Model
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Routers in an internet
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Routing Concepts

• Least cost routing
• Hop count
• Link-quality
• Speed, congestion, link medium

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Routing concepts

• Non-adaptive
• Adaptive
• Packet Lifetime

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Gateway and the OSI Model
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A Gateway
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Gateway

• Each Side Unaware of The OTHER
• Protocol Converter
• SNA -gt TCP/IP
• AppleTalk -gt TCP/IP
• Novell Netware -gt TCP/IP

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Other Devices

• Multi-Protocol Routers
• IPX, TCP/IP
• Brouter
• Router if known protocol
• Bridge otherwise

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Switches

• Function at Level 2
• Bridging Capability
• Store and Forward
• Telex
• Cut-Through
• Immediate Transfer

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Routing Switches

• Function as routers
• Faster than traditional routers
• USE Level 3 Network Addresses

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Distance Vector Routing

• Knowledge about the entire network
• Routing only to neighbors
• Information Sharing with neighbors

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Link State Routing

• Knowledge of neighborhood
• Shares with all routers flooding
• Information sharing when change

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Dijkstra Algorithm

• Breadth Search from root
• Select lowest cost
• Add node and arc

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Routing Classifications

• Adaptive routing (dynamic)
• Non-adaptive routing (fixed or static)

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Dynamic Routing Algorithms

• Distance Vector Routing
• Link state routing

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Routing Algorithms

• Distance Vector Routing
• Each link is assigned a weight
• Distance to the destination is the sum of the
  weights along the path to the destination

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Routing Algorithms

• Distance Vector Routing
• Each router sends its entire information about
  the entire network to its neighbors.
• Neighbors are other routers with direct link to
  it.
• Information are shared periodically, even if
  nothing has changed.
• Eventually, every router will learn about other
  routers on the network.
• Slow convergence (it takes longer for all routers
  to receive all information)

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Distance Vector Routing Protocol

• RIP (Routing Information Protocol)
• Each router uses broadcasting to send its entire
  information to its neighbors every 30 seconds.
• The best path is based on the least number of
  hops.
• Its suitable for small networks
• RIP is used by IPX/SPX and TCP/IP.

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Distance Vector Routing Table
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Routing Algorithms

• Link state routing
• If there is a change, each router sends its
  information about its neighbors to every other
  router in the network using flooding.
• A router, periodically sends a message to its
  neighbors, the response indicates that the device
  is alive and functioning.
• No response, change has occurred.

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Link State Routing Protocol

• OSPF (Open Shortest Path First)
• More efficient than RIP
• Only the changes are sent
• each router sends its information about its
  neighbors to every other router in the network
  using flooding.
• A router, periodically sends a message to its
  neighbors, the response indicates that the device
  is alive and functioning.
• No response, change has occurred.

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Concept of Link State Routing
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Costs in Link State Routing
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Link State Packet
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Flooding of As LSP
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Flooding of Bs LSP
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Link State Database
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Finding the Shortest Path

• Select a node (A) and make it permanent
• Examine each of the adjacent nodes to A.
• Relabel each one with the distance to A.
• Make the one with the smallest label permanent.
  (14)
• This becomes the new working node.

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Costs in Dijkstra Algorithm
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Shortest Path Calculation
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Link State Routing Table for A