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Cisco Auto MDI/MDIX Switch Support Matrix

MustafaAksu — Tue, 21 Sep 2010 12:58:42 +0000

You don’t need to use a crossover cable anymore to connect a switch to another one. Actually, the correct name of this switch feature is Auto MDIX (Medium dependent interface crossover). Let’s make a long story short. You just need a straight-through cable in between the PC (MDI type) and switch (MDIX type). A crossover cable is necessary when you have the same type on both ends like PC-to-PC or switch-to-switch connection. If the device supports Auto MDIX, it changes its port type itself according to the other side.

You MUST enable speed and duplex auto negotiation as prerequisite. You have to write down below commands on a Cisco switch to enable it.

speed auto
duplex auto
mdix auto

However Auto MDIX does not supported by all Cisco Catalyst switches.

Cisco Switches without Auto MDIX support
Catalyst 2950
Catalyst 3550
Catalyst 4948

Cisco Switches with Auto MDIX support
Catalyst 2940
Catalyst 2960
Catalyst 2970
Catalyst 3560
Catalyst 3750
Cisco IE 3000

FAQ Section:
Q1) Which pins are in use in MDI &MDIX type ports?
MDI : Pins:1 , 2 transmit 3 , 6 receive
MDIX : Pins:1 , 2 receive 3 , 6 transmit

Q2) Does it work if I use a crossover cable with an Auto MDIX port?
Yes, it does. Both straight-through and crossover cables work fine.

Q3) Can I fix speed & duplex and use Auto MDIX?
No. Auto MDIX uses speed negotiation process to recognize the other side’s port type. You have to use a crossover cable if you want to fix speed and duplex.

Q4) Do I need Auto MDIX on both interfaces to let it works?
No. It is enough if just one interface supports Auto MDIX but speed and duplex should be auto on both interfaces.

Before buying an RPS for Cisco Catalyst Switches

MustafaAksu — Wed, 07 Jan 2009 12:18:22 +0000

There are two issues that you have to be aware of when you are evaluating RPS solutions for fixed Cisco catalyst switches. Cisco has a product named Cisco Redundant Power System 2300 (RPS 2300) for the non-modular switch series like Catalyst 3560, Catalyst 3750. This is the successor of old Cisco Redundant Power System 675 (RPS 675).

You have only one bullet in your gun when you have an RPS

Switch draw power from the RPS after power fails

You can provide a limited redundancy to your network by installing an RPS for your Catalyst Switches. Switch survives without rebooting when the main power goes off. It draws power from RPS, but it never returns back to main power. An orange LED shows the switch powered by RPS. If you press the standby/active button on the RPS, your switch will reboot and become a normal operation. The only exception is E series switches + RPS 2300 combination. This combination could restore power state without rebooting.

RPS supports only one switch(in some cases two) at one time

Some of the switches will fail with a power circuit fail

You can attach up to 6 switches to an RPS, but if power Circuit 1 fails as shown in the above scenario then RPS only can support one switch and the rest will fail. RPS 2300 can support 2 switches if the power requirements are moderate, but no more.

Standalone or stackable Cisco switches do not support NetFlow

MustafaAksu — Sat, 11 Aug 2007 09:00:19 +0000

NetFlow is a must have technology suitable for mid size to enterprise companies. Nowadays, it has become an IEEE standard as IPFIX (Internet Protocol Flow Information eXport). We will be able to find NetFlow technology support on any brand in the market soon. However, which devices of Cisco itself supports NetFlow technology?

All routers including the oldest (e.g. Cisco 2500 series) and smallest (e.g. Cisco 800 series) support NetFlow. Some functions does not exist in older IOS versions.
Catalyst 6500 series switches support NetFlow. Catalyst 4500 series switches support NetFlow with Supervisor IV/V + WS-F4531 Catalyst 4500 NetFlow Services Card.

Standalone or stackable switches do not support NetFlow. This means Catalyst 4948, Catalyst 3750 or Catalyst 3560 series switches do not support NetFlow. You can see the necessary commands on config mode, but they are not effective. It is not about IOS version or feature set. You need a modular switch for NetFlow.

Unfortunately, the answer of “What Cisco switches support netflow?” is only the modular switches.

HSRP Group IDs are limited to 16 on PFC2

MustafaAksu — Sun, 29 Jul 2007 15:17:40 +0000

On the catalyst 6500 switches, the maximum number of HSRP group IDs are limited to 16 in the Supervisor Engine 2-based systems. This limit is 256 in all other older and newer systems.If you try to create a new standby group after this limit you recieve

More than 16 standby groups not supported in this platform.

message.Cisco says that this is a per interface limit. So, you can use same ID in several interfaces.

You can find the details on “HSRP Group Limitation on Catalyst 6500/6000 Series Switches Frequently Asked Questions”

Cisco Learning Credits

MustafaAksu — Sat, 28 Jul 2007 18:59:49 +0000

Getting training from Cisco is possible like buying a router. The process is similar to SMARTnet. You can simply add TRN-CLC-000 ( 10 Prepaid Training Credits:Redeem W/Cisco Learning Partners ) to your kit list and you have 10 Credits for training.

How can I use these credits?
You can use these credits for any training you need. You just have to check the required amount of credits from cisco.com to get trained. For example, you need 29 CLCs (Cisco Learning Credits) for Building Cisco Multilayer Switched Networks training (BCMSN). You can also attend the Networkers online. For the full conference pass, you need 19 CLCs.

Why should I buy CLCs instead of training?
If you work in a small company, you do not need it. But if you are working in a big organization (government, enterprise companies) it can be a real headache for you to participate in training. You should have within the training budget and it must be approved by HR department. This is not a simple process and involves permission from many people.

Otherwise, you have to prepare a kit list which includes hardware, software, SMARTnet and CLCs. All of them will be purchased together. In this way, if the logistics department comes with a wireless project in the middle of the fiscal year or the bosses decided to buy some security products after a security audit, then they will pay for necessary training without much discussions.

For the details please check “Cisco Learning Credits”.

Cisco Aironet Power Injector Media Converter

MustafaAksu — Sat, 28 Jul 2007 15:20:14 +0000

If you need a wireless solution on industrial areas like factories or warehouses, Cisco Aironet 1240AG Series Access Point would be a good option for you. The hardened case, wide range of antenna options and capabilities just make you feel that it is the best device. Unfortunately, if you have a closer look, you will see that this device only has a UTP (Copper) Ethernet port but no fiber options (Other models do not have fiber ports either). You require fiber to reach access points that are located at the far ends of a large warehouse. Moreover, you can have concerns about using a media converter from other vendors.

In this case Cisco has a solution.Cisco Aironet Power Injector Media Converter (AIR-PWRINJ-FIB) is a media converter and a Power over Ethernet (PoE) source. You just need a UTP cable between converter and Access Point. You can place the converter on a more convenient place than the access point. Thus, you do not need power cabling on the roof of the warehouse.

WARNING:This power injector only support Cisco pre-standard power. It means that it is not usable for other devices which requires 802.3af power ( e.g. Avaya IP telephone or non-cisco IP camera).

For the details please check the Cisco web site:Cisco Aironet Power Injector Media Converter