Monday, March 24, 2014

24 March 2014 - Routing

We are going old school today .... The Netacad.com site is down.

Todays topics:

crossover cables - build one

Router boot up process

reading the show version output

     look at wikipedia Cisco IOS for further info on understanding versions

static vs dynamic routing
     Routing Tables
      reading the show ip route command

encapsulation  HDLC, Frame Relay, PPP
hdlc, ppp, frame relay


Routing Protocols:

primary object is to determine the best patch to include in the routing table

May use one of the following metrics:  Hop Count (RIP) or Bandwidth (OSPF)

Path Determination:
     Directly connected network  (destination address in on same network as interface)
     Remote network (destination is on a remote network - packet forwarded to another router)
     No route determined (drops packet, send ICMP unreachable message to source)

The switching function of the router accepts the packet on one interface and forwards it out another.

          decapsulates layer 3 packet removing Layer 2 frame header and trailer
          examines IP address to find best route
          encapsulates Layer 3 packet in new Layer 2 frame and sends it out

     Layer 3 packet does not change except for the TTL.  Layer 2 updates source and destination data-link addresses.


clip on routers and routing

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