Networking

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1. Network architecture


 Distribution layer - which is sometimes referred to as the aggregation layer, provides route filtering and interVLAN routing. Management ACLs and IPS filtering are typically implemented at the distribution layer. The distribution layer serves as an aggregation point of access layer network links. Because the distribution layer is the intermediary between the access layer and the core layer, the distribution layer is the ideal place to enforce security policies and to perform and to perform tasks that involve packet manipulation, such as routing. Summarization and next-hop redundancy are also performed in the distribution.



2-tier architecture

Collapsed Core Layer


3-tier architecture


Cisco three-tier network design model


Core Layer - The core layer typically provides the fastest switching path in the network. As the network backbone, the core layer is primarily associated with low latency and high reliability.



2.  Power over Ethernet (PoE)


Cisco Catalyst switched monitor and policy PoE ports. If a device attempts to draw more power than a port is configured to provide, a syslog message will be issued and the port will be shut down and enter the error disable state.


Cisco Inline Power

PSE (Power Sourcing Equipment)


a) kinds of PoE

- PoE  from 2003 802.af (type 1) 15.4W

- PoE+  from 2009 82z.at (type 2) 30W

- PoE++ (4PPoE, UPOE) (2011) 802.bt (type 3) 60W CISCO

- PoE++ (4PPoE, UPOE) (2018) 802.bt (type 4) 90W CISCO


b) 2 Types of PoE

- Active

    - CDP protocol (LLDP protocol)

    - negotiation how many power device need 

- Passive

    - Always on

    - 24VPoE

    - ubiquiti (golden switch)

c) quiz

You have issed the power inline policy command from interface configuration mode on a Cisco switch. 

Which of the following best describes what will occur when an attached PD attempts to draw more than ists allocated amount of power from the configured interface 

a) The port will enter an error-disabled state.

b) The port will restart, and a log message will appear on the console.

c) The port will enter an error-disabled state, and a log message will appear on the console.

d) A log message will appear on the console.

answer: C)


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