Posts Tagged ‘ios’

VLANs in IOS and NX-OS

Tuesday, March 30th, 2010

There are always limitations and system-reserved resources on network platforms.  For years, certain VLANs have been “off-limits” on IOS platforms.  With NX-OS, we also have “off-limit” VLANs, however they are different from the IOS counterparts.


Nexus (NX-OS) protocol support (and cleanup)

Monday, March 29th, 2010

Over the years, Cisco has been very instrumental in the design and standardization of many networking protocols.  There are lots of examples where a need for a protocol was identified and Cisco filled the need with a Cisco-proprietary protocol.  Cisco-proprietary can sound bad, but it really isn’t.  Let’s give them some credit here – network equipment vendors are in competition and don’t typically play well together.  Often times vendors pitch proprietary solutions in an attempt to carve out a niche that delineates them from their competitors.

There are several standards organizations in existence today (IEEE, IETF, CableLabs, etc.) which many vendors work with and closely follow.  While this sounds ideal (and is very beneficial), standards often take a significant amount of time to be ratified, leaving any current needs unaddressed from a standards perspective.  The only alternative (for a quick resolution) is a proprietary solution, while the standards process is given time to complete. (more…)

Missing VLANs are not automatically created in NX-OS

Wednesday, February 17th, 2010

In IOS, if we assign a switchport to a non-existent VLAN, the switch will kindly create the missing VLAN for us. NX-OS does not do that – if a switchport is assigned to a missing VLAN, the interface will be placed in the down state. Let’s look at it… (more…)

EtherChannel behavior in NX-OS

Tuesday, February 9th, 2010

I’ve had a lot of discussions with clients about the behavior of Port-Channel interfaces and their associated physical counterparts.  It’s necessary for many parameters of the physical and logical interfaces to be the same.  Here’s the behavior within NX-OS and the preferred way that I make changes to EtherChannels.

In this, we’re going to continue working with the logical interface Po100 and the physical interfaces Eth1/19 and Eth1/20 which will be in the EtherChannel. (more…)

NX-OS – great interface range support

Friday, January 29th, 2010

(as I’ve been working with NX-OS as of late, I decided to jot down some thoughts and findings – this is one part in a series of posts on NX-OS)

Have you ever visited a friend’s house and said “I like what you’ve done with the place!”  Many of us have – in which case you should be able to relate to this post.  There are moments in working with NX-OS where I want to tell Cisco “I like what you’ve done with the place!”  This post is about just such a finding — the great support of interface ranges within NX-OS.


A Primer on Some of the Differences Between IOS and NX-OS

Sunday, January 17th, 2010

There are many similarities between IOS and NX-OS, however there are some significant differences as well. Before delving further into this topic, here’s what I was working with: NX-OS 4.0(1a)N1(1) (Nexus 5000) and IOS 12.4(17). This article gives a brief summary of the some of the differences (and similarities) of NX-OS and IOS. (more…)

Cisco VSS presentation

Wednesday, November 25th, 2009

Over the past couple of weeks I’ve presented to several Cisco User Groups on Cisco Virtual Switching System 1440 (VSS).  I’ve attached my presentation here (which can also be found on several Cisco User Group websites where I’ve presented).

This is (and is intended to be) a technical presentation, not a sales pitch or a high-level presentation.  Not only are configuration snippets shown, but some example scenarios are given. (more…)

Busy, busy, busy

Friday, November 20th, 2009

It’s been awhile since I’ve posted any articles.  I’ve been very busy with life.  Part of the busyness stems from studying other non-Cisco solutions (Juniper and Citrix).  I’ve been able to add several letters after my credentials from these vendors, including the JNCIA-ER, JNCIA-EX, JNCIA-WX, JNCIS-ER, JNCIS-ES and CCA NetScaler 9.  I’ve worked on keeping my focus within the R/S and data center (SLB, WAF, WAN optimization, etc.) specialties.


NVRAM errors when saving configuration

Thursday, June 25th, 2009

I was working on a client switch (VSS, modular IOS 12.2(33)SXH or IOS 12.2(33)SXI — I forget at this point) and ran into the following error message when attempting to save the configuration (more…)

Beware the config register…

Thursday, May 28th, 2009

Okay, I had a really embarrassing experience at a client site recently. While deploying a set of VSS switches, I ran into a sup that continued to boot into ROMMON mode. Typically this can be caused by:

  • Missing or invalid IOS image
  • Incorrect boot statement(s) in the configuration
  • Configuration register configured to boot into ROMMON mode
  • Corrupt memory (can happen)