Schlagwort: network

Enhancing Network Performance … Again

Last week I boosted network performance at Translink again.

The core switches used to be connected via single 1Gbit/s links, whereas all other ports are also 1Gbit/s. Unsurprisingly they had problems with several connections traversing the core. So I decided to increase the bandwidth (and by the way improve redundancy) by configuring an 8-port EtherChannel between each two core switches.

Of course the redundancy could also be improved by just patching more links between the switches, but in this case there would only be one usable link at a time, because the Spanning Tree Protocol (STP) would block the remaining links to prevent a loop in the network. By configuring the EtherChannel the switches consider the eight ports of the EtherChannel as one logical port and load-balance the traffic over all links.

Enhancing Network Performance

A project I’m working on that will never end is the enhancement of network performance, as there is always something that can be optimized.

So I did a lot of documentation work in the past week to reveal the most important things to optimize. After exposing the most crucial networking issues I started eliminating them: patching some more uplinks to improve redundancy, reconfiguring devices and so on. Unfortunately I cannot provide any details about the network here, as these facts are confidential.

But anyway, every configuration change I make and every uplink I patch is a small step towards a network which considers the best practices I have learned, e.g. the hierarchical network design:

Cisco Enterprise Campus 3.0 Architecture: The Layers of the Campus Hierarchy

Extending the Cisco Heaven

Another project I’m currently working on is the rollout of Cisco routers at Translink’s depots and garages, which are connected to the corporate network via ATM. At the moment these branch offices all use the standard all-in-one devices provided by the ISP. These devices unfortunately do not support advanced networking functions like VLANs, DHCP forwarding or routing protocols, which are needed for centralized network management. So that’s why they evaluate the Cisco router rollout.

After doing some internet research I configured my test device, a brand new Cisco 887VA, for PPP over ATM. After a failed test last week and a refinment of the configuration I successfully tested the setup at a train station near my office on Wednesday.

Cisco 887VA-SEC-K9
Cisco 887VA-SEC-K9

New Tasks, New Toys (Follow-Up)

As you can read in an earlier post, I had to set up a testing environment for Cisco Smart Install, which is now up and running.

The Smart Install director (the device which manages iOS and configuration deployment to the Smart Install clients) acts as a DHCP server and configures new switches coming factory settings with an IP address, default gateway and a TFTP server address (DHCP option 150). Right now the director deploys images and configuration files only to devices with specific MAC addresses, as I only want to configure my test client at the moment. It is also possible to filter deployment based on device model and type or IP address (if already configured).

Cisco Smart Install console output on client
Cisco Smart Install console output on client

After being upgraded and/or reconfigured by Cisco Smart install the switch is ready to be used in the corporate network without the need to be configured manually. This feature is also called zero-touch deployment. The Smart Install director console output shows the successful image and config upgrade process:

Cisco Smart Install Director console output
Cisco Smart Install Director console output

Network Documentation

As most of you employed in IT may know, there are always some projects you do „by the way“ (e. g. Oliver, René and Mateusz should know what I mean). 😉

I also got (another) „by the way“ project: document the whole Translink corporate network from core to access layer and from OSI layer 1 to 3. This includes all networking devices as well as every cable that connects two devices.

I think I will use a top down approach and start with the network core and WAN links between the sites and then care about the inhouse network site after site. Probably I will also have to develop a hostname scheme as not all devices in the network have unique hostnames yet.

I’ll tell you what I make out of it in later posts.

Have a nice weekend!

New Tasks, New Toys

After having heard that every new switch is configured manually and that there is no default configuration template, I suggested to use Cisco Smart Install to install and configure switches automatically. Bad idea! Now the shit hit the fan. My new task is to set up a testing environment for Cisco Smart Install. To do this I got a Cisco Catalyst 3750G L3 switch as well as a Cisco Catalyst 2960:

my new toys
my new toys

After searching for the documentation and CLI commands I plugged in the 3750G’s power supply and was totally euphoric … and then bitterly disappointed. There is no iOS image on the switch. 🙁 So I have to transfer an image via console cable which takes about 4 hours. It is not easy to stay calm when you want to start your work and recognize that you have to wait for the XMODEM console transfer at approximately 873 bytes per second. 😛 As I am writing this post I am still waiting for the XMODEM transfer to finish, so I think I won’t start configuring Cisco Smart Install today. 🙁

TGIF

I’m really looking forward to enjoying the weekend, so I think this picture best illustrates what I feel like. 😉

T.G.I. Friday's
Thank God it's Friday!

Yesterday I was given the task to document the MAC addresses of the devices that are connected to ten of Translink’s Cisco Catalyst 2950 access layer switches at Milewater Road. It took me about an hour with some e-mailing and surfing in between. Not a very interesting task, but at least some work on consoles of Cisco devices. 🙂

Now I’m keeping myself busy with documenting Mateusz’s business intelligence application again and waiting for the end of the work day at 2 o’clock …

Cisco Heaven

Yesterday my work day started with a visit at Translink’s „data center“ at Belfast Central Station.

They have servers …

server rack
Servers at Belfast Central Station

… networking equipment …

switches and cables
Some network equipment at Belfast Central Station

… and when it comes to structured cabling Translink strives for perfection! 😉

cabling
Structured cabling at Belfast Central Station

As you can see it’s rather a storeroom with a rack, some switches and an air conditioning system put in than a real data center.

I went there with my colleagues John and John, who both do most of the networking stuff at Translink. Why did we go there? The IS department just got a new redundant SAN system and plans are to move one part to Central Station to improve redundancy. To prepare this we met a network technician from Northgate (an IT service provider supporting Translink’s networking staff). He was introduced to Translink’s core network infrastructure with multiple sites connected via fibres and copper wires. After that he rushed through the core switch consoles, reviewed the configurations and presented some things that need to be changed in order to make the SAN replication work. We will get a full report soon.

The whole Translink data network is built on Cisco technology (as far as I know) so I hope there will be several opportunities to utilize my networking skills earned in the CCNA course in this (and coming) project(s).