Archive for the ‘General info’ Category

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Get-Console Review on the iPad

July 5, 2012

I have used my iPad to console onto Cisco routers and switches for about 2 years now. I started using the Flex-Serial cable on my jailbroken iPad and iPhone, with the iSSH app and a ported version of Minicom (earlier blog post).  Amidst some minor bugs and irritations this worked well and was considerably more convenient than carrying a laptop around the data centers. Earlier this year I ordered the RedPark RS232 cable from Get-Console.com, since the Flex-Serial cable was not available anymore. (It’s easy to notice to wear on my Flex-Serial cable). I have used the Get-Console solution ever since and will share the other reasons why I switched and give a product review. If you been thinking of getting this, it might be in your best interested to read this post.

The Redpark cable

Let me first compare the RedPark and the Flex-Serial cables.

Flex-Serial Cable

Redpark Cable

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Nexus load intervals

March 7, 2012

This is a interesting but a trivial post. Everybody know about the interface command “load-interval” that changes the time period over which the interface packet-rate and throughput statistics are averaged.

I discovered an addition to this command on the Nexus the other day while poking around. NX-OS allows multiple counter intervals to be configured on the same interface. This allows different sampled intervals to be listed at the same time.

The configuration is easy:

#interface Ethernet1/19
  load-interval counter 1 40
  load-interval counter 2 60
  load-interval counter 3 180

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Omnigraffle Stencil for Cisco Nexus

February 10, 2012

I am a MAC user and I have been looking but could not find a OmniGraffle Stencil with the Cisco Nexus icons, so I ended making one.

I have also submitted the stencil to Graffletopia.com

Feel free to download it and from Graffletopia or Mediashare:Cisco Nexus Hardware.gstencil.zip

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Cisco Nexus User Roles using TacPlus

August 28, 2011

I previously wrote a post about the Nexus Roles and how they integrate with a TACACS server.

Cisco Documentation shows the following format to issue multiple roles from a TACACS/RADIUS server.:

shell:roles="network-admin vdc-admin"

We are using Shrubbery TACPLUS, instead of the Cisco ACS software. Last week I noticed that only one role was assigned when multiples should be assigned. Multiple roles are required when using one TACACS server to issue roles for VDC and non-VDC Nexus switches since they need different default User-Roles.

This was tested on a Nexus 5000, a Nexus 7000 and VDC on the same Nexus 7000. Different codes were tried. This was not a NX-OS bug.

Upon further investigation it was obvious, that the syntax above as provided by Cisco was specific their TACACS software, being the ACS software. But I still required multiple Roles to be assigned for my single TACACS configuration to work across multiple Nexus devices. First attempt was the lazy method. Ask uncle Google for any such encounters with a solution. That yielded no practical results. I then contacting Shrubbery for the solution, after that it became clear that possibly nobody else have experienced this problem before.

So the hunt began to find out exactly what was so different in the AAA response from the Cisco ACS software to the TACPLUS software that it did not yield the required results.

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MPLS meet Nexus

August 2, 2011

The long wait is finally over. By long wait I mean more than 3 years. That is how long MPLS (Multiprotocol Label Switching) is late in delivery to arrive on the Cisco Nexus family of 10 GbE switches.

Why did it take so long? Especially considering that NX-OS has natively supported FIB table separation for a long time, more commonly known as VRFs (Virtual Routing and Forwarding). Yip, on NX-OS by default there are two VRFs, the Management VRF for the out-of-band management of the switch and the Default VRF for all in-band data interfaces. MP-BGP (Multiprotocol BGP) has been available for ages, all that was missing is LDP (Label Distribution Protocol) and perhaps for the more average network TE (Traffic Engineering) and RSVP.

So why the delay? Politics within Cisco, protection of specific BU product lines, perhaps a combination. Who knows! The exact answer is likely hidden somewhere deep within Cisco Confidential land. But who cares now that basic MPLS functionality is added right?

MPLS along with many other cool features included in NX-OS 5.2(1) for the Nexus 7000 platform was released last week. This is mostly good news, but also comes with some bad news.


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Nexus’ improved CLI

May 19, 2011

The Cisco Nexus Series platform has some good things going. Having spent much of my time recently using them, I have come to appreciate some very neat improvements NX-OS is offering over standard IOS. For the most part driving NX-OS is very similar to IOS, but it’s been greatly improved.

One such example is the output from the most used IOS command “show ip int brief”, which on NX-OS only shows ‘IP’ (being layer 3) interfaces. To see the brief state of all types of interfaces use “sh int brief” instead.

N5K-2(config)# sh ip int brief
IP Interface Status for VRF "default"(1)
Interface            IP Address      Interface Status
Vlan19               10.1.19.6       protocol-up/link-up/admin-up
Vlan22               10.1.22.6       protocol-up/link-up/admin-up

N5K-2(config)# sh int brief
--------------------------------------------------------------------------------
Ethernet      VLAN   Type Mode   Status  Reason                   Speed     Port
Interface                                                                   Ch #
--------------------------------------------------------------------------------
Eth1/1        1      eth  trunk  up      none                       1000(D) 51
Eth1/2        22     eth  access up      none                        10G(D) -
Eth1/3        1      eth  trunk  down    SFP not inserted            10G(D) 50
Eth1/4        1      eth  trunk  down    SFP not inserted            10G(D) 50
Eth1/5        1      eth  trunk  down    SFP not inserted            10G(D) -
Eth1/6        19     eth  access down    SFP not inserted            10G(D) -
Eth1/7        1      eth  trunk  down    Link not connected          10G(D) 5
Eth1/8        1      eth  trunk  down    Link not connected          10G(D) 5
Eth1/9        1      eth  fabric down    Administratively down       10G(D) 9
Eth1/10       1      eth  fabric down    FEX identity mismatch       10G(D) 7
Eth1/11       1      eth  fabric down    vpc peerlink is down        10G(D) 34
Eth1/12       1      eth  fabric down    SFP not inserted            10G(D) 12
Eth1/13       1      eth  fabric up      none                        10G(D) 15
Eth1/14       1      eth  fabric down    Administratively down       10G(D) 9

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Troubleshooting random Nexus reboots

March 13, 2011

November last year, a pair of Cisco Nexus 5010 switches, suddenly started rebooting randomly without user intervention.  Since these boxes were a front to a VM environment, stability were of urgent concern. But in order to stabilize the environment, the root cause of the reboots had to be isolated, and quickly.

The Cisco Nexus platform might not be as mature as many would like, but it is quickly becoming a very needed switch in Next-Generation datacenters. Of the things I like most about the Nexus boxes are the readily available local reporting and intuitive system checks.  Obviously there are many other features which is making the platform so popular. I’ll cover some of these in time.

Coming back to the rebooting issue. Unlike IOS devices that looses all local logging info, unless a crash dump was saved to NVRAM, the Nexus writes most of its log information to disk. Thus even after the reboot, you have all the information.
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