My Study Journey

show controllers to check  the type or health of cables

Modern Cisco Switches support auto-mdix which allows you not to worry so much about the cables connecting the devices. But for the test you have to know this:

straight-through – unlike devices

crossover – for like devices

UTP – unshielded twisted pair is common.

DTE – data terminal equipment.

DCE – data communications equipment.

 

 

Cisco break up networks into three easy to manage layers to tiers.

Access Layer – Provides workgroup/user access to the network as a result this layer is sometimes called the workstation layer.

Distribution Layer – policy based connectivity and controls the boundary between the access and the core layers

Core Layer – fast transport between distribution switches within the enterprise campus. called the bone layer

Access Layer

• Layer 2 Switching
• Port Security
• QoS classification and marking and trust boundaries
• ARP
• VACLs
• Spanning Tree
• PoE and auxiliary VLANs for VoIP

Distribution Layer

• Aggregation of Lan or WAN links
• Policy-based security in the form of ACLs and filtering
• Routing services between LANs and VLANs between routing domains
• Redundancy and load balancing
• Boundary for route aggregation and summarization configured on interfaces towards the core layer.

The Core Layer

• Providing high-speed switching.
• Providing reliability and fault tolerance

 

Collapsed Core Design takes the functions of the distribution layer and moves them (collapses) them into the core layer.

 

Cloud services

• Can be requested on demand
• Can dynamically scale
• Use a pool of resources
• Offer variety of network access options
• Can be measured and billed back to the user

Cloud Technology

• IaaS – cloud provider makes available to the client – hardware, software, servers, storage, other infrastructure components
• SaaS – cloud provider makes powerful software available to clients.
• PaaP – cloud provider makes virtual machines available to clients virtual machines so that they can develop software applications in a test environment. Software development tools are also provided as a part of the platform.
• XaaS – Any aspect of IT that is delivered through the cloud model

 

Firewalls – Can be implemented as software as software running as an application on OS, might be built in to os, might be a network appliance. Comes in different forms. The job is to protect one portion of your network or computer system from another portion. Device connects to inside protected network from outside. outside network is usually the internet. ASA is a Cisco firewall. ASAv is a virtual version of that.

Access Points – connects users to network quickly and efficiently as possible with security.  Usually dual band because they support frequency bands for various iterations of 802.11 wireless standards.

Wireless Controllers – Manages many access points in one environment. Brains of the operation and control aspects like security and frequency usage and antennae strength.

Wireless networks often use CSMA/CA – carrier sense multiple access with collision avoidance. Carrier sensing is used, but nodes try to avoid collisions by transmitting only when channel is sensed to be idle.

LAN with ethernet cables use carrier sense multiple access with collision detection. Listens to other signals while transmitting, if it detects that there are two sending at the same time, it stops transmitting, frame, then sends jam signal and waits for random time before resending.

Wireless Lan Controllers configure wireless policies, management, or security settings at anytime through centralized provisioning and management. Faster response to business needs by centrally managing wireless networks. Standardized access point configuration for software versioning. wireless intrusion prevention system capabilities, network wide qos for voice/video access wired/wireless networks, network wide centralized security policies across wired and wireless networks, mobility security and management for ipv6 and dual stack clients.

UDP – Connectionless, very little overhead, used for voice and video traffic, can multiplex using port numbers to work with multiple applications

TCP – Connection oriented, more overhead than udp, uses flow control, sequencing , acknowledgements to ensure reliable, ordered delivery of segments, can multiplex using port numbers to work with multiple applications.

TCP – HTTP, FTP, Telnet, SSH, SMTP

UDP – DHCP, RIP, SNMP, TFTP, DNS

TCP features  error recovery, flow control using windowing, connection establishment and termination, ordered data transfer, data segmentation.

 

OSI – Application, Presentation, Session, Transport, Network, Data Link, Physical

TCP/IP – Application, Presentation, Transport, Internet, Network Interface

Physical – Defines the electrical and Physical apps.

Data Link – Detects/corrects errors found at physical. Defines layer 2 protocols to establish and terminate a connection between two physically connected devices.

Network – Provides for logical network addressing, arp, to resolve layer 3 ip address to layer 2 mac ethernet address on lans.

Transport – Controls reliability of communication flow control mechanisms, TCP, for reliability, UDP for unreliability

Session – Controls connection between two systems it establishes, manages, and terminates connection between local and remote systems.

Presentation – layer ensures that network formats are converted in a way that application layer can understand them.

Application – services for end user apps so that communication with another app across network is effective

Data and header info are built at each of the layers.

 

Segments – Application

Packets – Presentation

Frames – Transport

Bits – Network Interface

 

 

 

Cisco Administrative Distance

• Static Route 1
• EIGRP 5
• BGP 20
• Internal EIGRP 90
• IGRP 100
• OSPF 110
• IS-IS 115
• RIP 120
• EGP 140
• ODR 160
• External EIGRP 1770
• Internal BGP 200
• Unknown 255