
Histoire de café
Lieux pour prendre un café a Paris ou pour trouver de quoi se faire une bonne tasse
Lomi ou l’on peut prendre un café sur place ou acheter du café
Coffee shop 3ter
3ter rue Marcadet – 75018 Paris
Sinon l’arbre a café (a coté de Réaumur) :
- Adresse de la Boutique
10 rue du nil, 75002 Paris - Adresse de l’Atelier
142 avenue du Maine, 75014 Paris
Happy 2019

Hello,
—-
Hello, a new year begins for us all as always many good things and soon for those who will cross my path and even those who will be only here. Have fun, enjoy these beautiful things for these new days.
Babel: Routing protocol
A french project for new routing protocol simple efficient:
https://www.irif.fr/~jch/software/babel/
It’s avoid routing loop
Optical amplification 100G and more for distance > 10km
In optical communication network, signal travels through fibers in
every large distances without significant attenuation. However, when it
comes to the distance up to hundreds of kilometers, to amplify the
signal during transit becomes rather essential. In this case, an optical
fiber amplifier is required to achieve signal amplification in long
distance optical communication. This article aims to give a brief
introduction to the most deployed fiber [amplifier— Erbium doped fiber
amplifier
(EDFA)](https://www.4fiber.com/wdm-optical-network/edfa.html?lipi=urn%3Ali%3Apage%3Ad_flagship3_pulse_read%3BzkwpjuCWQbyowJSDogVyyg%3D%3D).
What is EDFA?
An
EDFA is an optical or IR repeater that amplifies a modulated laser beam
directly, without opto-electronic and electro-optical conversion.
Generally speaking, it is an optical repeater device that is used to
boost the intensity of optical signals being carried through a fiber
optic communications system.
Working Principle of EDFA
EDFA
serves as a kind of optical amplifier which is doped with the rare
earth element erbium so that the glass fiber can absorb light at one
frequency and emit light at another frequency. An external semiconductor
laser couples light into the fiber at infrared wavelengths of either
980 or 1480 nanometers. This action excites the erbium atoms. Additional
optical signals at wavelengths between 1530 and 1620 nanometers enter
the fiber and stimulate the excited erbium atoms to emit photons at the
same wavelength as the incoming signal. This action amplifies a weak
optical signal to a higher power, effecting a boost in the signal
strength. The following picture shows 13dBm output C-band 40 channels
booster EDFA for DWDM Networks.

The Advantages of EDFA
The
EDFA obtains the advantages of high gain, wide bandwidth, high output
power, high pumping efficiency, low insertion loss, and it is not
sensitive to the polarization state.
It provides in-line
amplification of signal without requiring electronics, and the signal
does not need to be converted to electrical signal before amplification.
The amplification is entirely optical.
It provides high power transfer efficiency from pump to signal power.
The amplification is independent of data rate.
The
gain is relatively flat so that they can be cascaded for long distance
use. On the debit side, the devices are large. There is gain saturation
and there is also the presence of amplified spontaneous emission (ASE).
The Applications of EDFA
The
EDFA was the first successful optical amplifier and a significant
factor in the rapid deployment of fiber optic networks during the 1990s.
By adopting it in conventional optical digital communication system
applications, we can save a certain amount of optical repeaters.
Meanwhile, the distance relay could also be increased significantly,
which is vital for the long-haul fiber optic cable trunking systems. The
EDFA is usually employed in these circumstances:
EDFA can be
employed in the high-capacity and high-speed optical communication
system. It offers a constructive and ideal solution for handling low
sensitivity of receivers and short transmission distances because of a
lack of OEO repeater.
In addition, EDFA can be adopted in
long-haul optical communication system, such as land trunk optical
transmission system and the submarine optical fiber cable transmission
system. It helps to lower construction cost dramatically by reducing the
quantity of regenerative repeaters.
Moreover, EDFA can also be
employed in wavelength-division multiplexing (WDM) system, especially
dense wavelength-division multiplexing (DWDM) system. It enables the
problems of insertion loss to be solved successfully and reduces the
influences of chromatic dispersion.
Conclusion
By
far, being the most advanced and popular optical amplifier, EDFA has
been widely adopted in the optical fiber communication networks.
Featured by flat gain over a large dynamic gain range, low noise, high
saturation output power and stable operation with excellent transient
suppression, it surely will capture a rather vital and indispensable
position in optical communication in the near future.
Sample [EDFA products](www.4fiber.com)
Other documentations
Optimizing and Scaling on a Leaf-Spine Architecture
Posted by (and sources): Mike Peterson on May 05, 2016
Source: her/ici
Description
The Internet of Things (IoT)
and the proliferation of virtualization have caused traffic between
devices in the data center to grow. Referred to as “east-west traffic,”
this term accounts for traffic going back and forth between servers in a
data center.
When you run lots of east-west traffic through a
topology designed for north-south traffic (traffic that enters and exits
the data center), devices connected to the same switch port may contend
for bandwidth – and end-users experience poor response time.
If
hosts on one access switch need to quickly communicate with hosts on
another access switch, uplinks between the access layer and aggregation
can be a point of congestion. A common three-tier network design may
worsen the issue, constraining the location of devices like virtual
servers.
Moving to a Leaf-Spine Architecture
That’s where leaf-spine architecture
comes in, scaling horizontally through the addition of spine switches.
This two-layer topology allows devices to be exactly the same number of
segments away.
With each leaf switch connecting to each spine
connection, the number of spine switches is limited to the number of
uplink ports on the leaf. The most common leaf switches come with only
four 40G QSFP+ uplink ports, limiting your network to only four spine
switches. This starts to limit network scalability.
One way to
achieve more scale is to break the 40G SR4 channel into four 10G duplex
channels, turning the four 40G uplink ports into 16 available uplinks.
This increases the number of spine switches that can be a part of the
mesh network to 16, providing four times the scalability.
Scaling Networks: 10G vs. 40G
Let’s use an example to compare scaling in leaf-spine architecture between 10G and 40G networks.
With
40G uplinks, the number of spine switches is fixed at four, based on
the leaf having four uplinks. Typically, each spine has a total of four
line cards. These line cards come with 36 40G ports per line card. The
total number of available ports to connect to leaf switches is 144; each
leaf has 48 ports to connect to network devices, allowing for a maximum
of 6,912 computers to connect to the 40G mesh network.
When you
scale out on a 10G network, scaling is increased by a factor of four.
Each 40G uplink is broken into four 10G channels, allowing for 16 spine
switches. With four line cards, and 36 40G ports per line card split into 10G legs, there are
a maximum of 576 leaf switches (144 ports x 4). With each leaf having
48 ports, you can connect 27,648 computers – four times the scaling
throughout the mesh network.
10G Channels: Potential Obstacles
Moving to four 10G channels in leaf-spine architecture introduces a new concern: Latency
(the amount of time it takes for a packet of information to travel from
point A to point B) increases because the pipes are split into smaller
lanes. The smaller the lanes, the slower the traffic. Although
throughput remains the same, latency increases.
One of the biggest challenges to
implementing a mesh network is cabling. Mesh networks require LC patch
cords to create a cross-connect, ensuring that all leaf switches and
spines are properly connected. A cross-connect is created in the main
distribution area (MDA), creating several cabling issues: insertion
loss, maintaining polarity, increase in cable counts, etc. Rack challenges include density, required U space and power availability.
To
create the 10G channel, a complex cross-connect must be created. Each
eight-fiber MPO port on the switch is broken up into an LC duplex
connection; 144 MPOs become 576 LC duplex connections per switch, for a
total of 18,432 LC duplex ports (both sides of the cross connect).
To connect the 10G channels to each leaf and spine, a total of, 9,216
LC duplex patch cords are needed. As a result, additional channels for
MACs (moves, adds and changes), cable routing and space constraints are
possible.
This essentially breaks an MPO into four lanes and
makes an LC connection. Each lane is combined with lanes from other
spines and converted back into an eight-fiber MPO (Base-8) with four
channels from four different spine switches. Cable management, space utilization, documentation and labeling become extremely difficult to troubleshoot and maintain.
Shuffle Cassettes Save Space and Reduce Complexity
There’s
a new leaf-spine architecture solution available that drastically
reduces the amount of space needed, as well as the number of cables in
the MDA: Belden shuffle cassettes.
These cassettes eliminate the need to create a cross-connect to separate 40G channels into 10G,
and recombine to connect to each leaf, handling lane reassignments
internally. Each shuffle cassette has four MPOs in and out; each leaf
requires four shuffle cassettes.
COMPARING TOTAL MODULES
<table><tbody><tr><th>Traditional
MPO-LC-MPO</th><th>Belden Shuffle
Cassette</th><th>*Savings*</th></tr><tr><td>704
modules</td><td>416 modules</td><td>*288
modules*</td></tr><tr><td>176U
space</td><td>104U space</td><td>*72U (roughly
1.6 racks)*</td></tr><tr><td>9,216 patch
cords</td><td>2,304 patch cords</td><td>*6,912
patch cords*</td></tr></tbody></table>
By
utilizing the same connector, reducing connections and standardizing on
components across the channel, Belden’s shuffle cassettes allow for
scaling in leaf-spine architecture, reduce the opportunity for human
error, speed up deployment time and reduce time spent on MACs. By using a
shuffle cassette that fits into any Belden housings, you reclaim
valuable floor space.
Automation for network
Ansible on network world
Presentations
Ansible (Python)
Replay of Ansible presentation made by Francois
Ansible tutorial
Network automation with ansible
First configuration of network devices
Zero Touch Provisioning
Network definition language
looks a lot like cmdb light, same approach to config and design generation language defines objects and comiled to fill db they generate complete templates
Robotron top down network management at facebook scale
Talk 2: Wedge100 + Backpack: From the Leaf to the Spine Zhiping Yao + Xu Wang, Facebook
Other tools (not Ansible)
Opencontrail
[multi-hypervisor-support-using-opencontrail]
(http://www.opencontrail.org/multi-hypervisor-support-using-opencontrail/)
[qualisystems](http://www.qualisystems.com/)
Napalm
[napalm automation]
(https://github.com/napalm-automation/napalm)
[Napalm @spotify on Github](https://github.com/spotify/napalm)
More for DevOps Chef (ruby)
[chef]
(https://learn.chef.io/)
[Puppet](https://puppet.com/) (not used @Criteo)
Python for Network
[https://pynet.twb-tech.com/](https://pynet.twb-tech.com/)
Criteo Tools for network diff between 2 configuration files (Cisco/Arista) :
[https://github.com/criteo/netcompare?files=1](https://github.com/criteo/netcompare?files=1)
Why use Docker / Ansible in front of Puppet / Chef :
[http://thenewstack.io/are-docker-users-migrating-to-ansible-and-away-from-puppet-and-chef/](http://thenewstack.io/are-docker-users-migrating-to-ansible-and-away-from-puppet-and-chef/)
# Monitoring / Graphs
* Time series DB
[Opentsdb](http://opentsdb.net/)
[Grafana](http://play.grafana.org/#/dashboard/db/grafana-play-home?panelId=6&fullscreen&edit)
* Front-end
[Graphite](https://graphiteapp.org/)
[Elastic kibana](https://www.elastic.co/fr/products/kibana)
[ElasticSearch](https://www.elastic.co/fr/products/elasticsearch)
# Virutalenv (VM/libvirt/container/…)
If you want to test some apps/stuff you can use one of this « tools »
– Docker : [https://www.docker.com/](https://www.docker.com/)
– Virtualenv : (more for dev) [http://virtualenv.readthedocs.org/en/latest/](http://virtualenv.readthedocs.org/en/latest/)
– Vagrant : (more for dev) [https://www.vagrantup.com/](https://www.vagrantup.com/)
# Other
[http://druid.io/](http://druid.io/)
## Videos and presentations
Storm usage at Criteo: [http://www.infoq.com/fr/presentations/storm-criteo](http://www.infoq.com/fr/presentations/storm-criteo)
Youtube Network Automation and Programmability Abstracation Layer [https://www.youtube.com/watch?v=93q-dHC0u0I](https://www.youtube.com/watch?v=93q-dHC0u0I)
<iframe allowfullscreen= »allowfullscreen » height= »314″ src= »//www.youtube.com/embed/93q-dHC0u0I » width= »560″></iframe>
@34:47 you will find Steve Feldman.
The only feldman I know is him ?
<iframe allowfullscreen= »allowfullscreen » height= »314″ src= »//www.youtube.com/embed/h8VWASQB8wk » width= »560″></iframe>
Blog : [https://pynet.twb-tech.com/blog/automation/cisco-ios.html](https://pynet.twb-tech.com/blog/automation/cisco-ios.html)
# Tools for DEV
[http://sourabhbajaj.com/mac-setup/Python/virtualenv.html](http://sourabhbajaj.com/mac-setup/Python/virtualenv.html)
[http://hetland.org/writing/instant-python.html](http://hetland.org/writing/instant-python.html)
# Tools
[https://www.esev.com/blog/post/2015-01-pgp-ssh-key-on-yubikey-neo/](https://www.esev.com/blog/post/2015-01-pgp-ssh-key-on-yubikey-neo/)
# A Trier:
[https://github.com/digitalocean](https://github.com/digitalocean)
[https://www.digitalocean.com/company/blog/](https://www.digitalocean.com/company/blog/)
[http://xplproject.org.uk/](http://xplproject.org.uk/)
[http://networkstatic.net/programming/](http://networkstatic.net/programming/)
[https://www.opennetworking.org/blog/?Itemid=316](https://www.opennetworking.org/blog/?Itemid=316)
[http://northboundnetworks.com/collections/flowmaker](http://northboundnetworks.com/collections/flowmaker)
[https://herdingpackets.net/2014/02/06/using-the-cisco-csr1000v-in-gns3-with-virtualbox/](https://herdingpackets.net/2014/02/06/using-the-cisco-csr1000v-in-gns3-with-virtualbox/)
[http://highscalability.com/](http://highscalability.com/)
Network BGP on TOR
Layer 3 design with spine and leaf
Routing
* prefix list automation:
[Bgpq3](https://github.com/snar/bgpq3)
# Network design
### Google new network design
Read this paper: [Conferences sigcomm](http://conferences.sigcomm.org/sigcomm/2015/pdf/papers/p183.pdf)
### Facebook DC design
Information about 1st design @FB:
http://networkingnerd.net/2013/09/23/your-data-center-isnt-facebook-and-thats-just-fine/
Facebook DC design Next Gen:
Introducing data-center fabric the next generation facebook DC network
A video presentation about L3 spine and leaf @FB (useful demo @2’22 »)
[https://www.youtube.com/watch?v=mLEawo6OzFM&t=142]
Pictures of FB DC:
[Photo tour new facebook data-center in iowa (2014)](http://www.datacenterknowledge.com/archives/2014/11/20/photo-tour-new-facebook-data-center-in-iowa/)
Servers:
http://si.wsj.net/public/resources/images/BN-FO246_1114fb_WN_20141114145545.jpg
FB servers
### LinkedIn DC design plus L3
DC design spine and leaf and water-cooling at LinkedIn
[http://www.networkworld.com/article/3161184/data-center/linkedin-pumps-water-down-to-its-server-racks-uses-an-interesting-spine-and-leaf-network-fabric.html](http://www.networkworld.com/article/3161184/data-center/linkedin-pumps-water-down-to-its-server-racks-uses-an-interesting-spine-and-leaf-network-fabric.html)
And from linkedin blog:
[https://engineering.linkedin.com/blog/2016/03/project-altair–the-evolution-of-linkedins-data-center-network](https://engineering.linkedin.com/blog/2016/03/project-altair–the-evolution-of-linkedins-data-center-network)
### Other company L3 design
An old article from Metadata blog:
[http://muratbuffalo.blogspot.fr/2010/11/portland-scalable-fault-tolerant-layer.html](http://muratbuffalo.blogspot.fr/2010/11/portland-scalable-fault-tolerant-layer.html)
### Tools for network BGP and design
[http://www.pica8.com/company/press-releases/pica8-adds-bgp-support-extends-routing-to-the-data-center-edge.php](http://www.pica8.com/company/press-releases/pica8-adds-bgp-support-extends-routing-to-the-data-center-edge.php)
[http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/whitepaperc11-522337.html](http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/whitepaperc11-522337.html)
IETF draft for L3 in the DC:
[https://tools.ietf.org/html/draft-ietf-rtgwg-bgp-routing-large-dc-00](https://tools.ietf.org/html/draft-ietf-rtgwg-bgp-routing-large-dc-00)
Presentation from Nanog about
[https://www.youtube.com/watch?v=GNe_mIxQZcc](https://www.youtube.com/watch?v=GNe_mIxQZcc)
From Arista:
[https://www.youtube.com/watch?v=TLbzvbfWmfY](https://www.youtube.com/watch?v=TLbzvbfWmfY)
LoadBalancer
How to load balance applications in a L3 DC (Replay of a meetup)
[https://www.youtube.com/watch?v=MKgJeqF1DHw](https://www.youtube.com/watch?v=MKgJeqF1DHw)
Hardware
[http://www.qantas.com.au/travel/airlines/our-network/au/en](http://www.qantas.com.au/travel/airlines/our-network/au/en)
Latex premier documents
Utilisation de latex, mise en place d’un Docker avec tous les outils :
Dockerfile:
<pre class= »prettyprint linenums »><code>
#This is a comment FROM debian:jessie-slim
#FROM debian:jessie MAINTAINER Jerome Baudet <jerome@baudet.io>
RUN echo « deb http://ppa.launchpad.net/ansible/ansible/ubuntu trusty main » >> /etc/apt/sources.list
RUN apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 93C4A3FD7BB9C367
RUN apt-get update && apt-get install –fix-missing -y sudo curl texlive-latex-base texlive-xetex latex-xcolor texlive-math-extra texlive-latex-extra texlive-fonts-extra texlive-bibtex-extra fontconfig lmodern preview-latex-style texlive-latex-recommended tipa prosper preview-latex-style cabal-debian pandoc pandoc-data texlive-doc-fr sshpass openssh-client openssh-server vim vim-latexsuite
RUN apt-get autoremove
RUN apt-get clean
RUN mkdir /var/run/sshd
RUN mkdir /root/.ssh
COPY authorized_keys /root/.ssh/
RUN sed -i ‘s/PermitRootLogin prohibit-password/PermitRootLogin yes/’ /etc/ssh/sshd_config
#SSH login fix. Otherwise user is kicked off after login
RUN sed ‘s@sessions*requireds*pam_loginuid.so@session optional pam_loginuid.so@g’ -i /etc/pam.d/sshd
ENV NOTVISIBLE « in users profile »
RUN echo « export VISIBLE=now » >> /etc/profile
#will ease up the update process
#updating this env variable will trigger the automatic build of the Docker image
#ENV PANDOC_VERSION « 1.19.2.1 »
#install pandoc #
RUN cabal update && cabal install pandoc-${PANDOC_VERSION} #
EXPOSE 2200
VOLUME [« /data »] CMD [« /usr/sbin/sshd », « -D »]
#ENTRYPOINT /bin/bash
</pre></code>
What You Need to Know About Alien Crosstalk Today

Contact | Subscribe
– – – – – –
The industry has been predicting the growth of 10GBASE-T for years, and it’s finally happening. More networks are planning 10G migrations. Why? Due to demand from more advanced devices, users and applications.
But new concerns come into play with this Ethernet standard. Alien crosstalk – the interference caused by wire pairs in one cable inducing noise into other wire pairs in adjacent cables – is the transmission parameter that most significantly impacts 10GBASE-T performance.
## What is Alien Crosstalk?
Alien crosstalk is a combination of alien near-end crosstalk (NEXT) and alien far-end crosstalk (FEXT); the noise source originates from a common mode signal that is converted onto the differential mode signal through some type unbalance on cable and components.
## Why is Alien Crosstalk Bad for Today’s Applications?
In high-speed, high-bandwidth applications – used today to accommodate more users and more devices – alien crosstalk can cause many problems. In a cable bundle, it’s possible that cable pairs in one cable pick up interference from pairs of another cable. The digital signal processors (DSPs) used in [10GBASE-T architectures](http://www.ethernetalliance.org/subcommittees/10gbase-t/faqs/) can’t remove unpredictable exterior noise. Noise sensitivity increases at higher frequencies, such as 500 MHz, which is the highest frequency of Category 6A cabling.
This interference isn’t just a nuisance; it has the potential to shut your entire network down – which leads to unplanned downtime, financial losses, a productivity nosedive and unhappy users.
## What Causes Alien Crosstalk?
Alien crosstalk originates from a common mode signal that is converted onto the differential mode signal through some type of unbalance on the cable and components. Category 6A cabling and components are designed and tested to reduce alien crosstalk to a level low enough that it does not interfere with the differential mode signal.
Make sure all components are [Category 6A](http://www.belden.com/blog/datacenters/index.cfm?page=5). This is especially important to note for patch cords. When high-quality, Category 6 cable is tested, it may pass Category 6A patch cord requirements because only near-end crosstalk and return loss are measured. When these patch cords are bundled and placed in a Category 6A channel, however, the channel fails alien crosstalk requirements. Why? Because Category 6 cable isn’t designed to handle high data-speed requirements.
Don’t over-tighten cable ties. Cable ties that increase tension can force cables together and impact alien crosstalk. When using cabling ties to dress the cabling, make sure the ties are free to rotate after tightening.
## What Do Standards Say About Alien Crosstalk?
[[Poll Goes Here]]Alien crosstalk reduces cabling’s operational bandwidth due to increased channel noise levels; as a result, ANSI/TIA standards state that [Category 6A cabling](http://www.belden.com/blog/datacenters/Installing-Category-6A-The-Future-is-Now.cfm) best meets the demands of 10G. (According to current standards, Class E and Category 6 cabling aren’t recommended for new 10GBASE-T installations over 37m.)
Here are a few reasons why Category 6A is the best choice:
– Achieving [10GBASE-T](http://www.hpctoday.com/best-practices/10-things-to-know-before-deploying-10-gigabit-ethernet/) over copper requires 500 MHz bandwidth and full duplex transmission, which Category 6A provides
– It must follow stringent ISO/IEC and ANSI/TIA transmission-parameter regulations
– It uses specially designed jackets and cross-webs that physically separate internal twisted pairs from external twisted pairs, ensuring low alien crosstalk
– It provides a guaranteed alien crosstalk margin above minimum TIA-568-C.2 requirements
– Category 6A specifications allow compliant cabling for 10GBASE-T transmission
Belden’s Category 6A cabling solutions provide a simple design without compromising performance or quality, ensuring robust performance and reliable networks. Learn more about our [10GSX cables](http://info.belden.com/10gxs), which feature a smaller diameter, a rounder jacket, a smaller bend radius, fewer twists and easy-to-remove barrier tape.
<div style= »text-align: center; »>[](http://info.belden.com/ecos/iot-convergence-wp)</div>Source: Spine and Leaf (1st) test