Distributed Core Network Architecture

There is no doubt you have probably heard by now the importance of supporting ‘east-west’ traffic flow in large data center networks. So why is this and what does it mean? And when Gartner claims that 80 percent of data center network traffic now travels from server-to-server, just what impact does this have on network design/architecture? Continue reading

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XenServer, Hyper-V, and ESXi – Architecture, API, and Coding

VirtualizationBelow is a link to the slide deck for a presentation I gave to some friends/colleagues for a Berkeley Virtualization and Cloud Computing certification course I took in early 2012. For my final project I did a XenServer, Hyper-V, and ESXi hypervisor comparison in regards to market share, architecture/installation, and APIs/coding. The project involved not only a presentation but coding for all three hypervisors – XenServer, Hyper-V, and ESXi. Technical details, demos, and coding examples are provided in the presentation. You can also download all code from either the download section of this site or for the latest code updates download from GitHub. Continue reading

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Dell Force10 – Layer 2 Multipathing via Virtual Link Trunking (VLT)

In this blog I use one Dell Force10 S50N [FTOS 8.4.2.7] and three Dell Force10 S4810 switches [FTOS 8.3.12.1] to demonstrate Dell Force10’s layer 2 mulipathing technology called Virtual Link Trunking (VLT). With VLT, you can create a LAG for a server, switch, or any device that supports LACP to two different upstream switches.

Traditionally, a LAG from an access switch or server could only connect to a single upstream switch. For redundanacy purposes, many users would implement stacking on the upstream switches and then use a port-channel/LAG up to the stacked switch now seen as one logical entity. However, stacking is not the preferred solution here. Two main reasons for this is that stacking provides a single control plane mechanism that is managed by the master switch; there is no hitless failover. Compare this to VLT which provides a dual control plane mechanism and is hitless in nature. Additionally, when upgrading the switch firmware, the entire stack would need to be brought down. With VLT, one switch can be upgraded at a time without bringing down the other switch.

Stacking is more seen at the ToR or access layer. The ToR switches are usually stacked and VLT is then used upstream to the aggregate and core switches. However, if the ToR switch supports VLT such as the S4810 does, VLT can also be used from the switch down to the server. 1 GbE switches like the Dell S50N and Dell S60 do not support VLT, so, in these cases, stacking can still be employed.

In the least recommended approach, if no VLT or stacking is used at the aggregate layer connecting to the ToR on a layer 2 network, spanning tree protocol (STP) would need to be employed to block redundant links. This would create link and switch level redundancy. The issue with this is that you lose half the ports/bandwidth on the switch. By leveraging VLT, you can have an active-active multi-path connection from an access server/switch to two upstream switches seen as one logical entity employing a dual control plane mechanism. No putting-up with STP or blocked ports! Continue reading

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Multi-Area OSPF in a Mixed Cisco and Dell Force10 Environment

In this lab I use one Cisco 2621XM [IOS 12.4(2)T], one Cisco 2621 [IOS 12.3(18)], one Cisco 3660 [IOS 12.1(1)T], one Cisco 3640 [IOS 12.1(2)T], one Cisco 3550-24PWR-SMI [IOS 12.2(44)SE6], one Dell Force10 S60 [FTOS 8.3.3.7], and one Dell Force10 S50N [FTOS 8.4.2.6] to demonstrate multi-area OSPF in a mixed environment of Cisco and Dell Force10 switches. Below is a diagram of my lab setup. Continue reading

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Blocking Hackers From Accessing Your Switch via Telnet/SSH

It’s amazing how much rattling at the doors and attempted intrusions companies become accustomed to seeing on their networks. Here I show a simple way to block telnet/SSH access to your switch. First, you should never use telnet to manage your switch over the Internet because the traffic is sent unencrypted and it is therefore insecure; SSH is the better option. Perhaps you only want to manage the switch from an internal network or only want to allow or block some hosts from using telnet/ssh. Below, I block all telnet/ssh access to the switch. I’m using a Dell Force10 S50N switch [FTOS 8.4.2.6]. Continue reading

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Trunking and DHCP Across Dell Force10 Switches

I did this lab some time back and thought it would be useful to post. In this lab I use a Dell Force10 S25P (FTOS 8.4.2.6) switch and Dell Force10 S50N (FTOS 8.4.2.6) switch to demonstrate trunking and Dynamic Host Configuration Protocol (DHCP) for multiple subnets. Both of these switches are layer 2/3 switches, however, I use the S25P to do all the routing and use the S50N strictly as a layer 2 switch. Continue reading

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Gratuitous ARP and Basics of Connecting a Cisco IOS Switch with a Cisco CatOS Switch

Cisco Catalyst C4003

Cisco Catalyst C4003

Some of you may have an old Cisco Catalyst switch laying around that you may want to put to use. CatOS is the old Cisco operating system for Catalyst switches that predates IOS; it can still be found on some of the old Catalyst switches which are now End of Life (EOL). In this lab I connect a Cisco Catalyst 3548-XL (Model WS-C3548-XL-EN) [IOS 12.0(5)WC13] with a Cisco Catalyst 4003 chassis (Model WS-C4003) [CatOS 5.5(20)] to demonstrate basic configuration and switching between the two. Gratuitous ARP is also discussed and demonstrated in this lab. The setup is as shown in the below lab diagram. Continue reading

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Using Dell EqualLogic iSCSI Arrays for Remote Storage

Dell EqualLogic storage can provide an easy and cost effective solution for adding remote storage to your virtualized environment. The PS Series Storage arrays can be a great solution as you can easily expand storage by combining multiple PS Series storage arrays into a single storage area network (SAN). For instance, the PS6100XS is a 2U chassis which provides 13TB of storage using 2.5” disks (7 hot-pluggable solid state disk (SSD) drives and 17 hot-pluggable serial attached SCSI (SAS) hard disk drives). Continue reading

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NVIDIA – Pushing the Limits of the GPU in “Batman: Arkham City” [Video]

I wouldn’t say I’m a big “gamer,” but I do once in a while like to play video games more to see the advancements in graphics/compute technology than anything else. PC games are usually my choice as the quality seems to far surpass those of video consoles. The latest PC game I tried just this weekend was “Batman: Arkham City”; to say the least I was very impressed. Continue reading

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Updating Windows XP/Vista/7 Graphic Card Drivers

If you are running Windows XP/Vista/7, you can find more info on the exact model of the graphic card by doing the following:
Continue reading

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