I prefer to use port-channel interfaces for the fabric interfaces when connecting fabric extenders (FEXs). If a single interface in the bundle fails, it won’t remove the fabric extender interface – it simply reduces it’s bandwidth. This results in stable, predictable, redundant and resilient behavior. Let’s prove this point. (more…)
Posts Tagged ‘fabric interface’
Why EtherChannels should be used for FEX interfaces
Monday, February 8th, 2010Experimenting with Static Pinning
Thursday, February 4th, 2010What happens when more links are associated with an FEX than are permitted in the max-links parameter? Let’s find out…
The FEX information is cached until it’s re-assigned to a different FEX
Tuesday, February 2nd, 2010Continuing 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, 2010Continuing 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?
(more…)
Methods for connecting FEXs
Friday, January 29th, 2010If 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).
Introducing the Nexus 2148T (Fabric Extenders)
Friday, January 29th, 2010The 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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