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Showing posts from May, 2016

[Proxy ARP] What is Proxy ARP?

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Why I mention Proxy ARP is because in OpenStack environment, this function exists in FIP namespace with DVR enabled. The way to check whether the FIP namespace's Proxy ARP enabled is here:
# ip netns exec fip-545b57e2-0fa5-46da-89a2-591f7a5474ce cat /proc/sys/net/ipv4/conf/fg-2f3f4992-23/proxy_arp
1

We also can see the arp and ip mapping:
# ip netns exec fip-545b57e2-0fa5-46da-89a2-591f7a5474ce ip neighbor
10.12.20.32 dev fpr-6ddabb95-1 lladdr 42:72:88:ca:07:72 STALE

The following is the explaination about Proxy ARP
http://linux-ip.net/html/ether-arp-proxy.html

Occasionally, an IP network must be split into separate segments. Proxy ARP can be used for increased control over packets exchanged between two hosts or to limit exposure between two hosts in a single IP network. The technique of proxy ARP is commonly used to interpose a device with higher layer functionality between two other hosts. From a practical standpoint, there is little difference between the functions of a packet-fi…

[Docker] the first experience with building docker image

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It is essential to look for the docker image first if you need some services or functions running on docker container. But, once you want to customize it, you probably need to build your own docker image. The official document gives you a very complete description for you to do so. Please refer to this https://docs.docker.com/engine/userguide/containers/dockerimages/
The following command list are my steps to build a customized Drupal docker image.
The are two ways to build your own image:
1. Updating and committing an image First, it would be better to have a Docker Hub account like this:


Second, to create a repository for your docker image.


If it's done, you can see this:



So, we can continue to the next step.
# Download the offical Drupal docker image
$ docker search drupal
$ docker pull drupal
$ docker images

# Create a container and update it ( be aware of the follwing parameters )
$ docker run -i -t --name danny_drupal -p 8000:80 drupal /bin/bash
  -i, --interactive           …

[Python] Problem with Python logging RotatingFileHandler in Django website

If seeing the log files are not rotated properly or correctly in Django web site, you most likely encounter the problem as the following article described:

Problem with Python logging RotatingFileHandler in Django website
"The log is done via RotatingFileHandler which is configured with 10 log files, 1000000 byte each. The log system works, but this are the log files I get: -rw-r--r--1 apache apache 83Jul2313:30 hr.log -rw-r--r--1 apache apache 446276Jul2313:03 hr.log.1-rw-r--r--1 apache apache 999910Jul2306:00 hr.log.10-rw-r--r--1 apache apache 415Jul2316:24 hr.log.2

[Linux Bonding] 802.3ad bond interface has shown RX dropped packets

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If someone uses Linux Bonding and finds some or a lot of RX dropped packets in bond interface, please ignore these dropped packet message because of the following informations:

1. Linux Bonding and Single Nic with 1GE switch are no difference in packet loss
I use iperf tool with UDP to test packet drop and jitter and the result shows that there are no difference of packet loss between linux bonding and single nic.




2. Bond0 RX packet dropped is not a bug.
Please check out this: https://bugs.launchpad.net/ubuntu/+source/bridge-utils/+bug/1041070
This is related to the bonding mode and _not_ a bug. The bonding module will drop duplicate frames received on inactive ports, which is normal behavior. [0] Overall the packets should be getting into the machine without problems since they are received on the active slave. To confirm this do the following 1) Check dropped packets from all interfaces. So if eth0/eth1 are connected to bond0, we may see dropped packets for bond0 and eth0, but not for…