Archive for February, 2009

Q&A – What do I need for CCNP lab?

Saturday, February 21st, 2009


I am currently working on my CCNA (ICDN2 test in 1 week!) and wish to
move to the CCNP track.

I really need help with the lab! I have done due diligence by
researching but just ended up more confused: I have been Googling for
the past 3 days.

I do not want to cut many corners on the lab. I have a reasonable
amount of cash to spend (up to $1000 is my target) and my lab has a
good start already.

Currently my lab looks like this:

2651 < -----I plan to convert this to an access server with 16 port (2 x8)octal using the correct NM module. 3640, 2 FE NM, 1 CSU/DSU #Switches 2960G 2950 (2) #Misc Aironet Access point 1100 Pix 506E 20U rack Thanks in advance. Charles


Nexus 7000 NX-OS upgrade

Friday, February 20th, 2009

I decided to upgrade our two Nexus boxes to the latest code before putting them on the network. The procedure is a bit different compared to a regular IOS upgrade. You need to download two files– the NX-OS image, and the “kickstart” image that corresponds to it. I chose to connect to the management port on the supervisor to upload the image. It’s in its own vrf so don’t forget that when trying to ping, etc.

Here is the process below as I did it ::

switch(config)# inter mgmt 0
switch(config-if)# ip address
switch(config-if)# no shut
switch(config-if)# end

switch# ping vrf management


Book Review – ExamCram CCNA Voice

Wednesday, February 18th, 2009

ExamCram CCNA Voice 640-460

Pearson was kind enough to send me a copy of ExamCram CCNA Voice 640-460 to review. I have to honestly say that this was my first time ever reading an ExamCram book so I was very curious to see what they are all about.

First off, I’m extremely glad to see some expansion in the associate Cisco certifications. I think this will make it a lot easier to get more exposure to the Voice, Security and Wireless tracks. Seeing that they now have voice offerings is a great thing for both employers and their employees. Man, I look forward to being able to teach CCNA again!


Supervisor Upgrade

Tuesday, February 17th, 2009

This past week, I upgraded one of our Sup-720s to the new Vs-720 which supports VSS (virtual switching system). I’m not using VSS at this time, but we will in the near future. We are only using a single Supervisor in each of our distribution switches. I did some work in the lab to make sure the supervisor upgrade would be as quick and painless as possible. Our access switches are all dual homed to another distribution so the impact would typically be minimal.

Here is what I did for the supervisor upgrade ::

I had the new supervisor running in a lab switch for a few weeks. Our production switches are fully loaded 6513 switches and what I was using in the lab was 6506 switches.

1. Let Supervisor burn in for 2-4 weeks in a lab.
2. Backup current config of production supervisor (this will be used to prep the new supervisor). Also record output of “show ip inter brief”
3. Establish base config for new supervisor.


Clean up those SPANs

Monday, February 9th, 2009

We recently started an eval with a product from NetQoS called SuperAgent. Basically, this device passively monitors application performance. It sits off a span or mirror port on the network. We are also using a product called Gigastor which feeds mirrored traffic to SuperAgent as well.

One thing to remember about SPAN configurations is that you have to be very selective about what you are spanning, because mirror ports can be quickly overwhelmed. A lot of times you know what servers you want to mirror traffic from, so you just span all of those source ports or even worse an entire source vlan.

The other thing to keep in mind is that you need to span in such a way to prevent duplicate packets if possible. If you start blindly mirroring all your servers, you may find yourself with duplicate packets which can throw off your packet loss and retransmission delay metrics. You have to remember that when mirrored servers talk to each other, you will certainly end up with duplicates. If you have a multi-tiered application where you have front-end servers talking to back-end, you definitely want to clean up those SPANs!

The most common method of traffic mirroring is using SPAN or RSPAN with Cisco switches. Using a network tap is also a very good method as well.

Here is an example of a scenario where you need to take care in what ports you choose to mirror.

Two Tier