Worth Reading: Hacking through subaudible commands
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Cisco Starship Pushes Data Center Management to the Cloud
It’s part of Cisco’s push to “Merakify” its business.
How VM is started
Starting up a virtual machine (VM) is not an easy task, there are a lot of things going on hidden from the plain sight and studying it alone is a challenging task. The goal of this post is to simplify the process of learning how the oVirt hypervisor works. The concept of the oVirt is illustrated in the process of starting up the VM, which covers everything from top to the bottom.
Disclaimer: I am an engineer working close to the host part of the oVirt, therefore my knowledge of the engine is limited.
Architecture
Let me start with explaining the main parts oVirt hypervisor architecture. It will help a lot in understanding the overall process of the VM startup flow. Following is the simplified architecture, where I omit auxiliary components and support scripts. This will allow me to focus on the core concept without distractions.
The architecture comprises of three main components: 1) web UI and engine, 2) VDSM, 3) guest agent.
The web UI is where the user makes the first contact with the oVirt hypervisor. The web UI is the main command center of the engine and allows a user to control all aspects and states of Continue reading
DevOps Barbarians at the Gate
Like it or not, operations teams will need to learn how to code.
Interview Questions for CCNA Candidates with Answers- Basics II
After out Part-I, we are again with Part-II
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| CCNA Interview Questions |
What command copies router configuration from NVRAM to a file server?
copy startup-config tftp
What command assigns and enables IPX on an interface?
ipx network 4a
How does TCP provide flow control and error checking?
Acknowledgements and windowing.
Using Cisco IOS, what PPP data compression methods can be used?
Stacker and Predictor.
What command can verify Application layer connectivity?
Telnet.
What command switches from User to Privileged mode?
enable
What command will deny all telnet traffic from subnet 2.1.3.0?
deny all telnet traffic from 2.1.3.0
Which of the following exist at the Transport Layer?
LLC
IP
SQL
UDP*
ARP
What command line keyword matches Ethernet_SNAP?
snap
Among the five classes of TCP/IP addresses, how many are available to the public?
3.
After entering the command ‘router igrp 50,’ what command enables IGRP on the router for interace E1, with an address of 155.88.3.5 and a mask of 255.255.255.0?
network 157.89.0.0
In what OSI layer do EBCDIC and ASCII exist?
Presentation.
What command Continue reading
Are VXLAN-Based Large Layer-2 Domains Safer?
One of my readers was wondering about the stability and scalability of large layer-2 domains implemented with VXLAN. He wrote:
If common BUM traffic (e.g. ARP) is being handled/localized by the network (e.g. NSX or ACI), and if we are managing what traffic hosts can send with micro-segmentation style filtering blocking broadcast/multicast, are large layer-2 domains still a recipe for disaster?
There are three major (fundamental) problems with large L2 domains:
Read more ...A short Story on vPC- Virtual Port Channel in Cisco Datacenter Environment
Today I am going to talk about vPC and vPC+. These two technologies are used in the datacenter environment over the Cisco Nexus Switches where you bundled the links.
vPC stands for Virtual Port Channel and is a virtualized technology, So it allows links that are physically connected to two different Cisco Nexus 7000 Series devices to appear as a single port channel to a third device. The third device can be a switch, server, or any other networking device that supports link aggregation technology.
There are lot of benefits of vPC which can allow to work better in your datacenter environment
vPC stands for Virtual Port Channel and is a virtualized technology, So it allows links that are physically connected to two different Cisco Nexus 7000 Series devices to appear as a single port channel to a third device. The third device can be a switch, server, or any other networking device that supports link aggregation technology.
There are lot of benefits of vPC which can allow to work better in your datacenter environment
- It actually eliminates Spanning Tree Protocol blocked ports
- with the help of vPC, you can use all the uplink available bandwidths
- Allows dual homed servers to operate in active-active mode
- Providing Fast convergence on link failures
- Providing dual active default gateways for servers
- Simplify your network design and build high resilient and robust Layer 2 Network.
- Excellent Scalability and seamless virtual machine mobility.
So now I will talk about the various components used in the vPC environment. I hope datacenter guys already heard and know about these components. I will just put the component and the meaning of Continue reading
Cisco Router as Terminal Server- Why and how to configure
Today I am going to talk about the Cisco Router as a Terminal server in the datacenter environment. So the question is why and where we are going to use the terminal server?
Let's talk about the Terminal server what exactly is and why we are using the Terminal server in the datacenter environment.
Terminal Server:
Let's talk about the Terminal server what exactly is and why we are using the Terminal server in the datacenter environment.
Terminal Server:
A terminal server commonly provides out-of-band access for multiple devices. A terminal server is a router with multiple, low speed, asynchronous ports that are connected to other serial devices, for example, modems or console ports on routers or switches.
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| Fig 1.1- Cisco Router as Terminal Server |
A terminal server works via a reverse telnet operation. Next, connect the asynchronous octal cable(s) to the 2511's 68-pin SCSI interface(s). Then connect a rolled console cable from the COM1 port (serial) on your PC to the console port on the terminal server. Power the device on and use a terminal emulator such as HyperTerm to connect.
The terminal server allows you to use a single point to access the console ports of many devices. A terminal server eliminates the need to configure backup scenarios like modems on auxiliary ports for every device. You can also configure Continue reading
Cisco SMI Still Exposing Network Switches Online
The number of exposed and vulnerable devices online has remained largely unchanged since researchers began exploring SMI in 2010.
Flow Trend
docker run -p 6343:6343/udp -p 8008:8008 sflow/flow-trendThe simplest way to run the software is using the docker. Configure network devices to send standard sFlow telemetry to Flow Trend. Access the web user interface on port 8008.
Liveblog: Cloud Native Infrastructure
This is a liveblog of the HashiConf 2017 session titled “Cloud Native Infrastructure.” The speaker is Kris Nova, a Senior Developer Advocate at Microsoft. Kris, along with Justin Garrison, authored the O’Reilly Cloud Native Infrastructure book (more information here). As one of the last sessions (if not the last session) I’ll be able to attend, I’m looking forward to this session.
Kris is a self-confessed Linux lover, loves writing in Golang, is a Kubernetes maintainer, and works on Azure at Microsoft.
So, what is “cloud-native infrastructure”? To answer that, Nova first tries to answer “what is a cloud?” Nova breezes by that definition without going into any real detail (or any real definition), and proceeds to talk about what infrastructure is. Again, Nova breezes by that without providing any real definition or depth, and proceeds to ask “Why is infrastructure better in the cloud?” According to Nova, infrastructure is better in the cloud because management can be as simple as an HTTP request. The next few slides in Nova’s presentation compare the “traditional” ways of managing infrastructure (provisioning switches, patching cables, troubleshooting problems) are now, when infrastructure is in the cloud, as simple as a series Continue reading