Tag: Cisco Systems

Converting from old to new with the PIX to ASA Migration Tool

Digging through Internet I’ve found a very good article from David Davis explaining how to make your life easier when migrating from PIX to ASA.

The important thing to note about PIX and ASA configurations are that they are different. In other words, to do one thing on a PIX requires a different command on an ASA. The ASA uses a more “IOS-like” configuration where the PIX has its own “PIX-OS” configuration. Here are just some of the differences between the two:

  • The ASA is different hardware and has different interface names.
  • The ASA uses sub-interface commands, like the Cisco IOS.
  • A PIX will use FIXUP commands for application inspection whereas the ASA will use policy maps.
  • On the PIX,outbound and conduit commands are used versus access lists on the ASA.

There are two ways to perform this conversion — manually or by using the automatic migration tool. You may want to perform the conversion manually if you want more granular control, but Cisco offers a PIX to ASA Migration Tool that can perform this automatically. Let’s look at how it works.

Read the full article at: Converting from old to new with the PIX to ASA Migration Tool


Cisco tips: Track down communication issues – Part 2

In the 1st Part of this series, I’ve described the most common steps that you should follow to troubleshoot a total lack of communication between a Layer 2 device (Cisco switch) and an end user connected device. As I promised here is the second part, in which I’ll try to show you what you can check when you have no problem with connection, but still you encounter a degradation in service. By this degraded service, I understand a scenario when you have packet loss for example, or intermitent connection which will affect communication and more than sure will make user users not very happy.

We will stick with the same scenario when a end user device is connected to a Cisco switch. Remember that until now, we just troubleshoot at the Layer 1 and Layer 2. Today we will stick in the same area, so nothing directly related to IP, routing protocols or complex networking environment.

Scenario 2: You have an end device connected to a switch and you have degraded communication

a) Check for errors on the interface:


In this example there is no errors, but if you find something there, you may want to keep an eye on this port. Try to issue the above command couple of times to see if the errors are increasing in real time, as this is the worst case possible and you should take action immediately. Error on the interface can be caused by faulty interface on the switch or on the other end, ethernet cable issue or wrong configuration

b) Check the interface queue and drop packets


Interface queue is very important and you should check it during your troubleshooting process. With the above command you can see how many packets are in the input / output queue, which is the transmit and receive rate and very important if you have packets dropped from input and output queue. Usually this happens when there is a lot of load on the switch and it cannot process as quick as it’s needed all the packets. This lead us to the next step.

c) Check the CPU load on the switch


The command output is longer but most interesting for this example are the first 2 rows which show load in 60 seconds and in 60 minutes. If you have there peaks up to 100, then it’s bad and the device is having some issues that need to be fixed.

d) Identify what process is keeping the CPU busy


Most of the time, this is easy to read and to see what process is taking all your CPU power. When you see there Fifo Error Detection with 100% than you have to think that maybe there is something wrong with the queue on one of the interfaces and try to find which one is having problem. This is not straighforward and you have to check a lot of things, but can be helpful. To be honest, I see a lot of engineers just reloading the device and then problem is solved (if it was due to a hardware issue and not a configuration mistake).

e) Check for memory issue on the switch


Again, if you run out of memory, bad things can happend to your device and as well to the communication with device connected to the switch. Reloading of the device solved about 90% of this kind of problems. I don’t recommend just unplug the power cable as soon as you see a memory problem. First have a look, maybe there is something you can fix without reloading the device.

f) Check for problems with storm-control implementation


In one of previous posts I have explained how you can use storm-control to limit the available bandwidth on a Cisco switch interface. In the example above I set this bandwidth to 1 % from the available one gigabit (I know is stupid, but imagine a typo mistake). Imagine what effect will this have on the traffic. Everything above 1 % is keeped in the queue until this is full and then silent discarded.

e) As a general rule, have a look into the logs (maybe this should be first step!)

If there are a lot of Spanning-tree reconfiguration, interface flapping or anything else that looks suspicious, be sure to check on this as you can find there the root cause for your problems.

Do you have any other tips in regard to this topic? Anything else you check and can be added here? Be sure to comment below and your suggestion will be taken into consideration.

Cisco Borderless Network – Phase 2

Everywhere where I turn my look in the last days I hear about the quick coming of Phase 2 of Cisco Borderless Network. If you are interested, you can register for the event on Cisco website .

I tried to search some documentation to understand what is Cisco Borderless Network and which is the big difference from Unified Communication , but all I could find is mostly marketing related documents which promise the next network miracle, everything interconnected, controlled and monitored from distance.

Then I turn myself to the Cisco blogging community to see what’s there, but also it seems that the things are not so clear there as well. Everybody know about the 5 phases of the new Cisco service:

  • Phase 1: Borderless Network Services – Delivering innovations IN and ON the network that optimize network availability, performance, and security.
  • Phase 2: Borderless User Services – Embedding key services spanning mobility, security, and application performance across all elements of the network.
  • Phase 3: Borderless Policy – Implementing a unified policy framework for managing security, identity, and access to the network and network resources.
  • Phase 4: Borderless Integration Framework – Bringing end-to-end network-to-endpoint intelligence through open, extensible interfaces into the network.
  • Phase 5: Borderless Experience – Converging services and systems to provide a superior customer and employee experience regardless of location, device, or application.

but I which also look more like a marketing ad, than network related topics. On phase 1, I was lucky enough and I could find some direction on technical blog of Ivan Pepelnjak, and in this phase it seems that everything was about the new ISR G2 release. Ivan have some objective observation about the Phase 1 of Cisco Borderless Network:

  • All the embedded “WAN” ports are Gigabit Ethernet uplinks. Good.
  • They claim up to 5-times higher performance than the previous routers. Average. The ISR series was launched in 2004 and Moore’s law predicts 5.8-times increase.
  • Lots of the old interface modules are supported. Amazing; I’m just hoping it doesn’t hurt the performance.
  • They’ve replaced the old half-hearted attempts to include an x86 generic application platform within a router with the Service Ready Engine (another great marketing invention … sounds so much better than a Linux blade) modules, having up to 4GB of RAM and 1TB of hard disk. I don’t want to know how the people who bought the old AXP platform feel reading these specs.
Now going back to the Phase 2, Jim Duffy on NetworkWorld.com Cisco subnet is presuming that this will include :
  • innovations in Cisco’s switching portfolio and how they are relevant to the company’s business
  • service-enabling solutions for video, energy management and trusted access
  • a competitive switching offer for the price-sensitive market segment
  • enhanced support and services

but still there is enough fog around the subject. I think I will register for the Phase 2 European event, on March 18 maybe I will get some more clues about Cisco Borderless Network.

Skipping all this marketing and technical stuff, I’m wondering if the world is really prepared for this. And when I’m saying world I mean networks. I really don’t know what to say. I mean I know it’s cool and maybe positive from financial perspective to turn off light in some remote location, but how your network will support this. If you turn your look around you’ll see that network engineers have more stressing problems with day by day operation like VoIP services, slow data transfer between data centers and LAN security, just to name a couple of my problems.

Another problem is the word of the day: costs. How much it will cost to implement all of this and will companies be interested in implementing such a solution? I know that from marketing perspective everything looks great, because that’s their job, to make it look great, but network engineers might have a different opinion.

If you have some news or thoughts in regard to this topic, please use with trust the comment form.

Cisco tips: Track down communication issues – Part 1

You know how sometimes you plug in everything, configure device / ports and then the un-expected result is “not working”. Then you start to troubleshoot, which is a good point, but very important is where are you looking for the root cause of your issue.

A lot of people who have communication issue start by issuing a ping from one end to the other one. This is a good approach when somebody is reporting service issue (e.g. my webserver doesn’t work) as with the ping you can see immediately if is a communication issue or a server one. This scenario ussualy occurs when you already have a working environment and after a while somebody encounter a service issue.

Instead when you just deployed a new connection and you are having issue with it, ping is not the best approach. In the following article I will try to show you some good steps proven to be effective when you start troubleshooting. For today I will take as example a faulty communication between a Cisco switch and an end device (server or user device). This involes in the first step basic Layer 2 troubleshooting.

Scenario 1: You have an end device connected to a switch and you have no communication

a) Check the interface connection status:

OK – port is connected and protocol shows up status

Not OK – check the faulty port as it is in shutdown state

Not OK – port is not connected, protocol shows down status
You can check for cable error (damage, faulty plug, unplugged) or ask the owner of the remote device to check it.

If you found any error in the above step, try to fix them now. If the interface is connected, but still not working, follow on to the next steps.

b) Check speed and duplex settings
-if you have auto-negotiation here and it fails, you will end with an interface in down status
-again if you have static settings here, check to be the same on both sides.
-for more pro and cons regarding auto-negotiation vs static, please see Greg Ferro’s article

c) Check the interface switchport configuration:


There is no right and wrong configuration here, but I can point you to check the following:
– very important, check if the access VLAN is the right one
– if you have switchport auto-negotiation enabled, check to see that this is correctly achieved
– if you have switchport static configuration, check to have the correct settings for your needs
– if you need trunking (to an end device), check to allow the necessary VLANs on that trunk
– if you use private VLANs, pay attention to the configuration of primary and secondary vlan and right association

d) Check security on the Access port (BPDU guard, port-security, mac-address access-list…):


– port is in shutdown state due to Security Violation (1); The mac-address that you see there is the one coming to the port from the other end, but also you can see that there is a Configured Mac Address (1) on the port; Most probably the one configured on the port does not match the one from the network.


-if the result is like above one, you may want to check if that mac-address access-list allow communication from end device mac-address


– if your interface status is like this, you might have an issue with spanning-tree BPDUguard being enabled on the interface; I know I said that this is end device connected, but what if the user needed an extra port, and he connected there a switch? You always have to assume what’s the worst and check for possible issue.

f) Check the Spanning-tree protocol on the switch port


– your output might look different than the above one, but be sure to have there FWD (Forwarding) status if the port is connected to an end device.
– again it is very rare not to be in FWD status, but if the device has some strange bridging capabilities or user added another device in the middle, like a switch than you can identify a problem with Spanning-tree.

This are the basic stuff that I checked in regard to Layer 2 topology when I have no communication to the end host. In the next part, I will do a short presentation of the scenario when you have communication to end device, but the connection encounter traffic deprecation.

Check the 2nd Part of this series which deals with communication deprecation at Layer 2.

Do you have any other tips in regard to this topic? Anything else you check and can be added here? Be sure to comment below and your suggestion will be taken into consideration.

How to integrate GNS3 with Virtual PC

In this article I want to show you how to extend your posibilities to test a network in GNS3. Sure, it’s simple sometime to use a Loobpack interface on one of your edge routers to simulate an external network, but sometime is useful to have something connected to the router port. Take as an example QoS marking and classification. If you want to mark something inbound, then you need a connection to the router port where you want to mark the packets.

Additional to my example here, which include Virtual PC Simulator, you can find useful tutorial about GNS3 and VMware integration on  gns3-labs.com or how to emulate a voice lab with the same tools on blindhog.net.

Even most of you are familiar with GNS3 and maybe Virtual PC Simulator, let me begin with some short description about this 2 software.


GNS3 is a Graphical Network Simulator that allows emulation of complex networks. It allows you to run a Cisco IOS in a virtual environment on your computer (running Linux, MacOS X or Linux). GNS3 is a graphical front end to a product called Dynagen. Dynamips is the core program that allows IOS emulation.

The Virtual PC Simulator (VPCS) allow you to simulate up to 9 PCs. You can ping/traceroute them, or ping/traceroute the other hosts/routers from the virtual PCs when you study the Cisco routers in the Dynamips. VPCS is not the traditional PC, it is just a program running on the Linux or Windows, and only few network commands can be used in it. But VPCS can give you a big hand when you study the Cisco devices in the Dynamips. VPCS can replace the routers or VMware boxes which are used as PCs in the Dynamips network.

Before we start, I assume that you already have these tools installed. If not, please download and install GNS3 and VPCS.

On the following example I will show you how to configure a network topology including 2 Virtual PCs and one router and how to interconnect them in GNS3. This presentation is simulate a basic network, but after you learn how to do it, you can configure more complex one. You can have a look to the topology to understand better what I’m talking about.

Please see the video presentation below:

gns3-virtualpc

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