Archive for the ‘Hardware’ Category

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Load-Sharing across ASICs

April 26, 2012

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 one ASIC.

Scenario 2- Failure of one switch on either side. The obvious solution available today is multi-chassis port-channels which addresses the problem 95%.

Consider the following topology:

Even with multi-chassis port-channel there is the still the possibility of an ASIC failure.  Although not as detrimental as Scenario-1, there will still be some impact (depending on the traffic load) if both interfaces on one switch happen to connect to the same ASIC.

Thus it only makes sense that the ports used on the same switch, uses different ASICs. How would confirm this on the Nexus 5000 and Nexus 7000?

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Cisco Nexus 7000 upgrade to 8Gb

February 27, 2012

When upgrading a Nexus 7000 to NX-OS version 5.2 (using more than 1 VDC) or to NX-OS v6+, Cisco claims the need to upgrade the system memory to 8Gb.

Note I have run on v5.2 using only 4Gb per SUP using 2 VDCs and it has worked just fine, but I should mention that the box was not under heavy load.

See how much memory your N7K has on a SUP by using the following command:

N7K# show system resources
Load average:   1 minute: 0.47   5 minutes: 0.24   15 minutes: 0.15
Processes   :   959 total, 1 running
CPU states  :   3.0% user,   3.5% kernel,   93.5% idle
Memory usage:   4115776K total,   2793428K used,   1322348K free

The upgrade per SUP would need the Cisco Bundle upgrade package (Product code: N7K-SUP1-8GBUPG=). One package has one 4Gb module. (see picture below) If you have two SUPs you would need two bundles. Notice the 8Gb sticker on module in the red block.

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Console to routers using the iPad

January 3, 2011

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Please note I have done a more recent post about using the iPad to console HERE

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Having had some free time finally, I’ve done what I have been meaning to for a while. That is use my iPad (instead of my laptop) everytime I need to run to the datacenter to console onto a Cisco router/switch. This is a complete tutorial how to use the iPhone/iPad for serial communication to Cisco devices. The iPhone works fine, but the small screen can be frustrating when doing large configs. The iPad on the other hand has enough screen real estate for this to be a pleasant experience.

What are required to do this?

  1. A serial connector cable  (30-pin Apple to male DB9 pin RS-232).
  2. A rollover cable.
  3. A jailbroken iPhone/iPad.
  4. Terminal application.
  5. Software that supports serial communication.
  6. Configuring the serial communication software.
  7. Crazy geek dance!

Step-1

The most challenging part was finding/making a serial communications cable. I use the Flex-Serial cable from Bestcelldist.com. This cable has dip switches on the sides making it ideal for almost any type of serial communication.

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Memory problems

June 6, 2010

From a question on groupstudy; the following output was posted of a Cisco 2600 that did not boot up even after the Flash was upgraded to 32MB??????

System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)
 Copyright (c) 2000 by cisco Systems, Inc.
 C2600 platform with 65536 Kbytes of main memory

 program load complete, entry point: 0x80008000, size: 0x1c8a8e4

 Error : memory requirements exceed available memory
 Memory required     : 0x04746F90

 *** System received a Software forced crash ***
 signal= 0x17, code= 0x4, context= 0x80080630
 PC = 0x0, Vector = 0x0, SP = 0x0

 System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)
 Copyright (c) 2000 by cisco Systems, Inc.
 C2600 platform with 65536 Kbytes of main memory

 program load complete, entry point: 0x80008000, size: 0x1c8a8e4

 Error : memory requirements exceed available memory
 Memory required     : 0x04746F90

 rommon 1 > dir flash:
 File size           Checksum   File name
 29928068 bytes (0x1c8aa84)  0x6ee9    c2600-adventerprisek9-mz.124-23.bin
 rommon 2 >

What could the problem be?

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