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CCNA (200-301) - 1.5 - Compare TCP to UDP (TCP vs. UDP)

TCP I like to think of as certified mail. The data is sent, and you receive a receipt confirming that it was received. Connection Oriented Protocol TCP requires a three way handshake to establish a conversation with the receiving end.  The Three Way Handshake Looks like This. The Sender will send a SYN (Sync) The Receiver will respond with a SYN-ACK (Sync-Acknowledgement) The Sender will respond with an ACK (Acknowledgement)  Now the connection will be established and traffic can be sent. Error Checking A checksum field is included within each seg...
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Cisco ACI - Adding a Tenant from Postman Using the API

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Before following these steps you need to have a token for the API stored in Postman.  The process for this can be found here . Creating the Tenant Right Click on your Collection Name (Cisco ACI Sandbox in my case), and click "Add Request" Right Click on your Collection Name (Cisco ACI Sandbox in my case), and click "Add Request" There are a couple steps in this piece: Name the Request "Create Tenant". Change the yype of request from GET to POST, since we're pushing a configuration. You can use the following URL to test against the sandbox, but you can change the hostname to your own APIC. https:// sandboxapicdc.cisco.com /api/mo/uni.json      4. Lastly in the Body you want to put the following JSON in place, and edit the name to whatever you'd like it to be.  {   "fvTenant" : {    "attributes" : {      "name" : " DBTN-Tenant "      }    } }     5. and finally, Click "Send" Now we will want to valid...
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Cisco ACI - Logging in from Postman Using the API

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 Most Network Engineers I know are like me, and are largely stuck in our ways of using the CLI. Cisco ACI is almost entirely GUI-based and really there isn't much you can do via the CLI.  Tasks that used to be so simple are now increasingly time-consuming. For Example; I had to configure an access port last week and it took me 10 minutes to get all the options correctly selected before I was done configuring the port. What used to be an easy procedure, whether manual or not, is now far more complicated, with several steps that can be easily missed.  To that end: I've started using the Postman Collection Runner to ensure I'm not missing any of the steps needed to complete these tasks.  Anyway, the first step to using the API is knowing how to get the API Token, which I'll now go over using Cisco's sandbox APIC found at sandboxapicdc.cisco.com. Open Postman, and click "+New Collection." Name it whatever name you prefer, and click "Create". Under yo...
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Cisco ACI - Adding a Tenant from the APIC GUI

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  Quick Steps on how to Create a Tenant from the APIC GUI. Step 1) Log into the APIC into the APIC. Step 2) Select 'Tenants' from the tabs at the top Step 3) Select "Add Tenant" Step 4) Name your Tenant then click Submit. Then you can go back to the All Tenants Tab and validate that the Tenant was created.
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Cisco ACI - Performing a Rebuild of an APIC

I recently ran into an issue where I had to rebuild an APIC in our ACI Fabric, and needed to rebuild it entirely.  The procedure is pretty simple, and I had ssh access to the device, so was able to complete it very quickly, you can also run this from the rescue-user either via ssh or console if all else fails. Run the following 3 commands: acidiag touch clean acidiag touch setup acidiag reboot Upon reboot it will bring you directly into the Setup Utility and you can add it back to the ACI Fabric. Official Documentation Source:  https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/1-x/troubleshooting/b_APIC_Troubleshooting/b_APIC_Troubleshooting_chapter_01001.html
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Cisco Nexus - vPC Peer-Switch

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The vPC Peer-Switch feature allows a pair of vPC peer devices to appear as a single logical Spanning Tree Protocol root. With vPC Peer-Switch enabled downstream devices see both switches as the STP root. Without vPC Peer-Switch enabled downstream devices still have to funnel Layer 2 traffic via the STP root using the traditional STP traffic flow. The main advantage of vPC peer-swtich is the improvement in term of convergence time during vPC primary peer device failure/recovery.    Without vPC peer-switch feature vPC primary peer device failure and recovery can create around 3 seconds of traffic disruption  With vPC peer-switch traffic disruption is lowered to sub-second value  This is since peer device down an up events do not generate any Rapid Spanning Tree Protocol Sync behavior, because, there is no logical change in the L2 topology. Things to keep in mind: It is a Cisco recommended best practice to activate vPC peer-switch within a vPC environment. vPC peer-swit...
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Cisco Fiber Channel Port Types

 Quick reference for which Fiber Channel port types can be used for are likely to show up on 350-601 and 300-625 Cisco Exams: • E Port • F Port • NP Port • TE Port • SD Port • Auto Mode E Port In expansion port (E port) mode, an interface functions as a fabric expansion port.  This port can be connected to another E port to create an inter-switch link between two switches. E ports carry frames between switches for configuration and fabric management.  They serve as a conduit between switches for frames destined for remote N ports.  An E port connected to another switch can also be configured to form a port channel.  F Port In fabric port (F port) mode, an interface functions as a fabric port.  This port can be connected to a peripheral device (host or disk) operating as an N port.  An F port can be attached to only one N port. NP Ports An NP port is a port on a device that is in NPV mode and connected to the core switch via an F port.  NP ports fu...
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