Tuesday 27 October 2009

Cisco Intelligent Information Network

The Cisco Intelligent Information Network (IIN) is a framework aims to align IT resources with business objectives across multiple products and infrastructure layers.

It aims to provide you with a route map to integrate resources and information assets, and benefit from a truely converged network infrastructure.

IIN helps to reduce maintenance costs of managing separate voice and data infrastructures.

IIN is achieve by following SONA as the architectural framework to guide your network development. Taking advantage of Cisco Unifiied Communication products and allowing you to virtualise your applications and infrastructure across multiple sites. It results in greater speed, enables scalability, and reduce costs.

To attain the goal of implementing IIN you need to progress through 3 phases
i) Integrate teh transport network
ii) Move to intregrate services
iii) Finally, intregrate the applications used in the enterprise.

Friday 23 October 2009

Cisco Service Orientated Network Architecture - SONA

courtesy of cisco.com

Right then, the first topic you'll cover off in each of the CCNP courses is SONA or how Cisco would like you to set up your network in order to sell you everything in their portfilio :o)

It details the common services deployed in the network and aims to reduce the gap between resources and applications.

Advantages include:
  • Offers a structured path to IIN (the Intelligent Information Network - discussed later)
  • Provides an outline to build integrated systems across a converged network through 3 phases
  • it increases the flexibility and efficiency in the business
SONA incorpates a Network Infrastructure layer, Interactive Services layer, and Application layer.

That's about it. Visit cisco.com for more information.

Monday 5 October 2009

Collision Domains vs Broadcast Domains

Collision Domains

layer 1 of the OSI model

A hub is an entire collision domain since it forwards every bit it receives from one interface on every other interfaces

A bridge is a two interfaces device that creates 2 collision domains, since it forwards the traffic it receives from one interface only to the interface where the destination layer 2 device (based on his mac address) is connected to.

A bridge is considered as an "intelligent hub" since it reads the destination mac address in order to forward the traffic only to the interface where it is connected

A switch is a multi-interface hub, every interface on a switch is a collision domain. A 24 interfaces switch creates 24 collision domains (assuming every interface is connected to something, VLAN don't have any importance here since VLANs are a layer 2 concept, not layer 1 like collision domains)

Broadcast Domains

Layer 2 of the OSI model

A switch creates an entire broadcast domain (provided that there's only one VLAN) since broadcasts are a layer 2 concept (mac address related) routers don't forward layer 2 broadcasts, hence they separate broadcast domains

With all this information, you can say that on your diagram, there are 2 broadcast domains (1 router that separates 2 LAN segments composed by one or many switches, with only 1 VLAN per segment).

There are 8 collision domains, one per pair of devices connected to each other (switch to router, switch to switch, switch to computer etc...) since we are talking about layer 1 concept (physical connection).

Thursday 1 October 2009

Administrative Distance

Administrative distance is the measure used by Cisco routers to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) using an administrative distance value. A lower numerical value is preferred, e.g. an OSPF route with an administrative distance of 110 will be chosen over a RIP route with an administrative distance of 120.
The following tables gives the default administrative distances used by Cisco routers.
Protocol Administrative distance
Directly connected route / static route using exit interface 0
Static route with next-hop IP address 1
EIGRP summary route 5
External BGP 20
Internal EIGRP 90
IGRP 100
OSPF 110
IS-IS 115
RIP 120
EGP 140
ODR 160
External EIGRP 170
Internal BGP 200
Unknown 255