What is a Fabric Extender

In this post I would like to cover the base of what is needed to know about the Cisco Fabric Extender that ships today as the Nexus 2000 series hardware. The Modular Switch The concept is easy to understand referencing existing knowledge. Everybody is familiar with the distributed switch architecture commonly called a modular switch: […]

The Next Nightmare is Coming

BitTorrent was NEVER the Performance Nightmare

BitTorrent is a lightning rod on two fronts: it is used to download large files, which Some puzzle pieces of a picture puzzle.the MPAA sees as a nightmare to their business model, and BitTorrent has been a performance nightmare to ISP’s and some users. Bram Cohen has taken infinite grief for BitTorrent over the years, when the end user performance problems are not his fault.

Nor is TCP the performance problem, as Bram Cohen recently flamed about TCP on his blog.

I blogged about this before but several key points seem to have been missed by most: BitTorrent was never the root cause of most of the network speed problems BitTorrent triggered when BitTorrent deployed. The broadband edge of the Internet was already broken when BitTorrent deployed, with vastly too much uncontrolled buffering, which we now call bufferbloat. As my demonstration video shows, even a single simple TCP file copy can cause horrifying speed loss in an overbuffered network.  Speed != bandwidth, despite what the ISP’s marketing departments tell you.

But almost anything can induce bufferbloat suffering (filling bloated buffers) too: I can just as easily fill the buffers with UDP or other protocols as with TCP. So long as uncontrolled, single queue Continue reading

Troubleshooting Common OpenStack Errors

##############General Tips############## /*Check all services $nova-manage service list (check for XXX or smiley face) Binary Host Zone Status State Updated_At nova-scheduler openstack1 nova enabled :-) 2012-05-12 22:42:14 nova-compute openstack1 nova enabled :-) 2012-05-12 22:42:12 nova-network openstack1 nova enabled :-) 2012-05-12 22:42:14 $ ps -ea | grep nova 11448 ? 00:02:54 nova-cert 12072 ? 00:02:57 nova-network […]

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Cisco UCS B440 Blade Replacement

Cisco announced recently a replacement program for their B440 blades (M1 and M2) http://www.cisco.com/en/US/ts/fn/634/fn63430.html Something I noticed on the front of each blade, where the model is shown, the new generation blades (replacements) have the black background with the silver text, shown as the top blade on the picture below: However, the old blades still have the black text with no background. An interesting way to identify the newer generation of hardware.

Cisco UCS B440 Blade Replacement

Cisco announced recently a replacement program for their B440 blades (M1 and M2) http://www.cisco.com/en/US/ts/fn/634/fn63430.html Something I noticed on the front of each blade, where the model is shown, the new generation blades (replacements) have the black background with the silver text, shown as the top blade on the picture below: However, the old blades still have the black text with no background. An interesting way to identify the newer generation of hardware.

N5K Stuck in Boot Mode

Another trivial post. The upcoming posts following this one will take a more in-depth look at the Nexus technologies. So you do an non-ISSU NX-OS upgrade on a Nexus 5000 switch and something goes wrong. After reload you get the following prompt: The switch did not successfully boot from the images it was suppose to. […]

OpenBSD 5.1 SNMP MIBs

It's May and that means a new version of OpenBSD is out. My SNMP MIBs have been updated for 5.1 and are available for download on the OpenBSD SNMP MIBs page. THIS WILL BE ONE OF THE LAST RELEASES OF THE MIBS FOR NET-SNMP During the OpenBSD 5.1 development cycle, I committed the CARP MIB to the base OpenBSD snmpd. The kernel sensor MIB has been in the base snmpd for a few releases now.

Management VLAN Best Practices in ESXi and Cisco UCS

If you’ve set up an ESXi host, you’ve likely seen this screen: This allows you to configure which VLAN is used for management. But what does this really do? Time after time I run into very smart engineers that primarily work on virtualization and not as much on the physical networking side - and they miss a few of the networking fundamentals that those of us that were brought up in ROUTE/SWITCH know and love.

Management VLAN Best Practices in ESXi and Cisco UCS

If you’ve set up an ESXi host, you’ve likely seen this screen: This allows you to configure which VLAN is used for management. But what does this really do? Time after time I run into very smart engineers that primarily work on virtualization and not as much on the physical networking side - and they miss a few of the networking fundamentals that those of us that were brought up in ROUTE/SWITCH know and love.

Who? What? When? Wired? Wireless? With Cisco ISE

Cisco's Identity Services Engine (ISE) is a powerful rule-based engine for enabling policy-based network access to users and devices. ISE allows policy enforcement around the Who?, What?, and When? of network access.

  • Who is this user? A guest? An internal user? A member of the Finance department?
  • What device is the user bringing onto the network? A corporate PC? A Mac? A mobile device?
  • When are they connecting? Are they connecting to the secure network during regular business hours or at 02:00 in the morning?

These questions can all be answered easily within ISE and are all standard policy conditions that are relatively easy to implement. In the post below I'm going to focus on the How? — How is the user or device connecting to the network? Asked another way, the question is Wired? or Wireless?

Review: Remote Desktop Connection Manager

It’s been a while since I’ve done a review of anything on the site and since I’d rather continue to make use of the category than delete it, I decided to share a piece of software I recently discovered that’s helping make my life easier. Remote Desktop Connection Manager is essentially just that - it manages remote desktop connections. However, it does it in a way that I find appealing and EASIER to use than the native client or other organizational methods out there.

Review: Remote Desktop Connection Manager

It’s been a while since I’ve done a review of anything on the site and since I’d rather continue to make use of the category than delete it, I decided to share a piece of software I recently discovered that’s helping make my life easier. Remote Desktop Connection Manager is essentially just that - it manages remote desktop connections. However, it does it in a way that I find appealing and EASIER to use than the native client or other organizational methods out there.

Load-Sharing across ASICs

Port-channels have become an acceptable solution in data centers to both mitigate STP footprints and extend physical interface limits. One of the biggest drawbacks with port-channels is the single point of failure. Scenario 1- Failure of an ASIC on one switch, which could potentially bring the port-channel down, if all member interfaces were connected on […]

My Cisco Live 2012 program

My Cisco Live 2012 program is below. I was able to select most of the sessions although there were some overlap with one session (something ARC overlapping with another ARC). You might note that the closing keynote is by the guys who play Mythbusters on TV - that'll most likely be a fun filled event! I'll blog about my pre-event feelings if I have the time and interest ;-)



Windows Server 2008 R2 Boot From SAN on Cisco UCS

For those that have worked with any type of blade server system, you know that boot from SAN is just about the coolest thing since sliced bread. Cisco UCS makes this even cooler by integrating with the service profile concept, allowing for stateless compute provisioning across the board. I’ve done boot from SAN many times, but never with Windows. I’ve primarily used ESXi4.1 or ESXi5.0 stored on a Fibre Channel LUN, then the VMs are stored in either a FC or NFS datastore.

Windows Server 2008 R2 Boot From SAN on Cisco UCS

For those that have worked with any type of blade server system, you know that boot from SAN is just about the coolest thing since sliced bread. Cisco UCS makes this even cooler by integrating with the service profile concept, allowing for stateless compute provisioning across the board. I’ve done boot from SAN many times, but never with Windows. I’ve primarily used ESXi4.1 or ESXi5.0 stored on a Fibre Channel LUN, then the VMs are stored in either a FC or NFS datastore.

A Quick and Dirty Netapp SnapMirror

Snapmirror is a Netapp feature that’s pretty commonly used to copy data from one system to another. You can copy volumes, or qtrees. It’s also very useful in Disaster Recovery plans, since volumes can be incrementally backed up to an offsite location. I have a VMWare vCenter instance running on Cisco UCS that utilizes a Fibre Channel LUN to store VM templates. It’s pretty large, since it holds templates for a variety of operating systems.

A Quick and Dirty Netapp SnapMirror

Snapmirror is a Netapp feature that’s pretty commonly used to copy data from one system to another. You can copy volumes, or qtrees. It’s also very useful in Disaster Recovery plans, since volumes can be incrementally backed up to an offsite location. I have a VMWare vCenter instance running on Cisco UCS that utilizes a Fibre Channel LUN to store VM templates. It’s pretty large, since it holds templates for a variety of operating systems.

Cisco UCS Firmware Upgrade Explorations

I’m currently working with a relatively large Cisco UCS installation. Initially, the system was installed and brought up to relatively recent levels of firmware, but a mismatch in the way that the firmware packages were set up in various sub-organizations on some of the UCS systems caused some of the blades to retain the old version of firmware on the M81KR adapters and the CIMC controllers. Due to the scope of the installation, I wanted to ensure that the blades were able to continue operating while I made my changes.
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