Posts Tagged ‘5000’

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.

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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…)

The FEX information is cached until it’s re-assigned to a different FEX

Tuesday, February 2nd, 2010

Continuing our journey into the world of FEXs on the Nexus 5000 and 2000, today we’re going to look at the behavior of the FEX configs themselves on the Nexus 5000.

All of the configuration and software information (firmware/images) for the FEX (Nexus 2148T) are kept on the parent switch (a Nexus 5000-series switch). Going on this, what happens when the FEX goes offline? Do I lose my config?

A stack of 3750 switches can be provisioned ahead of time, so that as stack members are added (assuming that they’re the correct type/model), no changes must be made – just move on. What kind of behavior is available on the Nexus 5000/2000?

I haven’t found provisioning available yet for FEXs on the N5k, however I did notice that the configurations for the FEX are retained when the FEX goes offline and online. This is great — if the 2148T fails or the fabric interface links are disconnected, the config will still be there (although not visible until the FEX comes back online). This article is looking at it from an association perspective (N2148T association with the N5k, not a configuration (actual port configs on the FEX). With that said, let’s explore this further… (more…)

What happens when the wrong serial number is entered for the FEX?

Sunday, January 31st, 2010

Continuing on the journey of FEXs on the Nexus platform, we’re exploring about serial numbers being statically bound to an FEX instance. It’s possible to allow any N2148T to connect to any FEX instance defined on a N5k. Simply plug in the N2k and off it goes.

This is a good low-maintenance approach, but what if I want to be more granular? What if I have several N2ks and I want to ensure that each N2k is plugged into the correct interfaces on the N5k? The only way to verify this is to tie a serial number to the FEX ID on the N5k, which will only allow that single N2k to come up on that FEX ID… or will it? What happens if the wrong serial number is entered?
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Methods for connecting FEXs

Friday, January 29th, 2010

If you’re wondering what an FEX is, check out this article: http://www.cciezone.com/?p=231.

FEXs are connected to the parent switch(es) via fabric interfaces.  These are 10Gbps interfaces which connect the two switches (think of a stacking cable on a 3750-series switch).

There are two methods of configuring fabric interfaces:

  • Static pinning
  • EtherChannels

Although these are somewhat differentiated in some of the documentation, the static pinning looks almost the same as that used for EtherChannels.  The main difference is that static pinning uses physical interfaces, whereas EtherChannel uses a single Port-Channel interface for the fabric interface (there are some minor configuration differences and requirements as shown below).

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Introducing the Nexus 2148T (Fabric Extenders)

Friday, January 29th, 2010

The Nexus 5000-series (5010 and 5020) support the Nexus 2000-series of switches.  The Nexus 2000-series are fabric extenders (FEXs) – which is essentially a way to stretch out the N5k switch fabric.  Currently there’s only the Nexus 2148T switch, which we’ll cover (at least the basics) in this article.

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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.

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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…)