Author Archives: Venkat

NetNORAD – Facebook TSHOOT tool

Interesting read and video about NetNORAD – a tool used by facebook to detect and isolate network latency/packet drop issues. https://code.facebook.com/posts/1534350660228025/netnorad-troubleshooting-networks-via-end-to-end-probing/   Additional reads: https://github.com/facebook/fbtracert https://github.com/facebook/UdpPinger

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Accessing HomePC from Anywhere[without traffic passing through a third-party app]

Create a free account with a Dynamic DNS service like noip.com and configure it in the modem. This step is to link dynamically assigned IP from your service provider to a static name. Install any remote sharing app like VNC … Continue reading

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Linux DHCP server config for PXE/BMP boot

Dell switches support Bare-metal provisioning(BMP) where a switch can be provisioned to automatically download image and config file from a remote server and boot up with that image file. In a nutshell, the process involves:

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IPv6 – Notes

IPv6: 128 bits. Represented in hexadecimal format as eight 16 bits segments. Two rules for IPv6 representation: Leading zeros in 16 bits can be represented as single 0. Single contiguous string of one or more segments are all zeros can … Continue reading

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BGP Notification Message

A BGP notification message is sent when an error condition is detected by the BGP process. The TCP connection with that BGP peer is closed after sending the notification message. Usually, the BGP process will log this notification in syslog, … Continue reading

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Python Script that SSH to a switch and execute commands for ‘x’ times

Below is a sample python code that can login to a switch via SSH and gather few command outputs and display it on console. SSH sessions are repeated for ‘x’ number of times. Paramiko SSH module is used in this … Continue reading

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Network Troubleshooting Methods

Troubleshooting a network connectivity issue is quite challenging in a complex Data Center Network with live production traffic. Below are few basic methods to identify a node in the traffic path that drops packets which would cause network connectivity issues. This procedure … Continue reading

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NPG (NPIV Proxy Gateway) Mode Vs Full Fabric Mode in FCoE

In this article, I will be discussing about two different modes that an FCF switch can operate in FCoE topology. FCF(FCoE Forwarder) is a switch that supports both Ethernet(FCoE) functionality like FIP, DCBx, LAN protocols and FC(Fiber Channel) functionality like … Continue reading

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Port names in FC/FCoE Topology

Following are most common port names used in FC/FCoE Technology: N_port(Node port)/VN_port: Ports on end host(i:e HBA) and storage array(target port) are called as N_port in FC topology. Called as VN_port in FCoE terminology. HBA’s that handles IP traffic are called … Continue reading

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Configuring Qlogic CNA for FCoE on an ESXi Host

This article is about how to configure FCoE functionality on Qlogic CNA card-QL8262 installed on a Dell PowerEdge R720 server running ESXi 5.5. QL8262 is dual port CNA card that supports LAN, iSCSI and FCoE. Configuring Qlogic FCoE card on an … Continue reading

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