Unanswered Question
Aug 28th, 2009

Welcome to the Cisco Networking Professionals Ask the Expert conversation. This is an opportunity to get an update on the Catalyst 3750E switches with Cisco expert Vipul Redey. Vipul is a product manager at Cisco's Desktop Switching Business Unit. Vipul has managed several Catalyst 3560 and Catalyst 2960 switching products. He joined Cisco six years ago as the product manager for various CiscoWorks network management products. Vipul is based at Cisco's headquarters in San Jose, California.

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j.miller_32 Tue, 09/01/2009 - 08:46

Can I stack the new 3750E switch with the 3750G switch without losing much?

Collin Clark Tue, 09/01/2009 - 13:26

The biggest thing you will lose is back plane capacity. The 3750E's operate with a 64-Gbps switching fabric and the non-E switch has a 32-Gbps switching fabric. If you stack them, the stack will drop to the highest supported back plane capacity of all the switches. In this case it would be the 32-Gbps switching fabric.

vipul Wed, 09/02/2009 - 13:41

That is precisely right. The stacking bandwidth steps down to the lowest common denominator, from the 64 gbps on the StackWise Plus on the 3750Es to the 32 gbps on StackWise on the 3750Gs. If you have an RPS 2300 wired up to such a mixed stack, please ensure that you have the E-series RPS cable connected to the 3750Es and the regular cable connected to the 3750 or 3750G.

mhankus Tue, 09/01/2009 - 11:09


When mixing 3750G with 3750E, one of 3750E becomes stack master, but what happens to second 3750E in mixed stack.

1. Will it support local switching ?

2. Packets on a ring between 3750Es, will be source stripped or destination stripped ?

vipul Wed, 09/02/2009 - 21:54

All E series switches will support local switching regardless of the stack type!

1. No, once you have a mixed stack, the switches (all) will only work in Stackwise mode.

2. Source stripped.

vipul Wed, 09/02/2009 - 22:28

OK - Let me try this one more time. :)

1. All E series switches will support local switching regardless of the stack type!

2. No, once you have a mixed stack, the switches (all) will only work in Stackwise mode - Source stripped.

lxcollin1 Tue, 09/01/2009 - 23:19

Hi Vipul,

Are there plans to make a multi-port 10Gb 3750E? If so, is there an ETA?


vipul Wed, 09/02/2009 - 13:46

No plans currently. However, our Catalyst 4900M product family can offer you terrific 10GE port density in a fixed configuration form factor.

I however would like to learn more about where you'd like to use such a 3750E.

vipul Wed, 09/02/2009 - 21:02

I believe what lxcollin1 is asking for here is a stackable version of the 3560E-12D. We have no plans to develop this.

l.canales77 Fri, 09/04/2009 - 10:19

Hi i currently have an etherchannel setup between 2 ports on my 3750e going to the 2 gi interfaces on the 3845 ISR in a lab environment. my question is regarding jumbo frames. when i reboot the ISR router it spits out alot of cautionary messages regarding my sub interface configuration, telling me to ensure jumbo frames are supported on both ends of the connection for the dot1q trunking. I believe both ends support it but i havent configured it, nor do i know if its necessary (the configuration seems to be working fine as is).

so i have 2 questions:

1. is it necessary

2. even if it isnt necessary, how would you do it. i have seen some documentation on enabling it for the switch, i havent seen anything for the isr. i do not have the isr infront of me to test at the moment.

vipul Fri, 09/04/2009 - 12:26

It is not necessary for Etherchannels to work. It is not set up by default, so if you need jumbo frame support, configure it as a global command.

Don't worry about the subinterfaces, as they are not supported on the switch. It's just a way for the router to handle 802.1Q by having a subinterface per vlan (subnet).

MachadoGB Fri, 09/04/2009 - 11:13

I have one stack with two 3750-E and only one switch with IP advanced services license to run OSPF. The second switch still has its original license (IP base). I got from Cisco a license file for the second switch (ip advanced). I have tried the normal procedure to install the license but it is stil not working. I am getting "xml parsing file" error. We ruled out the possibility of a corrupted file.

Is there any specific procedure to apply this license to the second switch while it is on a stack and running? Do I need to separate the stack to apply the license to the second one?

another question - do I need an specific file extension after the file name when I use the license install command?

another question - Do I need to use capital letters for the file name into the install command?

Why do I want that? - in case one fail the other one can handle the OSPF process (high avalability reasons).

Thank you.

vipul Thu, 09/10/2009 - 08:53

We'd need more details. What version of IOS are you using?

MachadoGB Thu, 09/10/2009 - 11:09

Vipul, Here you have more details -

0001-zbran-3750a#sh ver

Cisco IOS Software, C3750E Software (C3750E-UNIVERSALK9-M), Version 12.2(40)SE,


Copyright (c) 1986-2007 by Cisco Systems, Inc.

Compiled Fri 24-Aug-07 00:25 by myl

Image text-base: 0x00003000, data-base: 0x02000000

ROM: Bootstrap program is C3750E boot loader

BOOTLDR: C3750E Boot Loader (C3750E-HBOOT-M) Version 12.2(35r)SE1, RELEASE SOFTW

ARE (fc2)

0001-zbran-3750a uptime is 2 weeks, 4 days, 8 hours, 31 minutes

System returned to ROM by power-on

System image file is "flash:c3750e-universalk9-mz.122-40.SE/c3750e-universalk9-m


This product .....


If you require further assistance please contact us by sending email to

[email protected].

License Level: advipservices Type: Permanent

Next reboot license Level: advipservices

cisco WS-C3750E-48TD (PowerPC405) processor (revision E0) with 245760K/16376K by

tes of memory.

Processor board ID FDO1219V0FK

Last reset from power-on

6 Virtual Ethernet interfaces

1 FastEthernet interface

104 Gigabit Ethernet interfaces

4 Ten Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address : 00:1D:70:67:22:80

Motherboard assembly number : 73-10315-12

Motherboard serial number : FDO1219036X

Model revision number : E0

Motherboard revision number : B0

Model number : WS-C3750E-48TD-S

Daughterboard assembly number : 800-28590-01

Daughterboard serial number : FDO1216027L

System serial number : FDO1219V0FK

Top Assembly Part Number : 800-27544-04

Top Assembly Revision Number : A0

Version ID : V02

CLEI Code Number : COM9V10ARA

Hardware Board Revision Number : 0x01

Switch Ports Model SW Version SW Image

------ ----- ----- ---------- ----------

1 54 WS-C3750E-48TD 12.2(40)SE C3750E-UNIVERSALK9-M

* 2 54 WS-C3750E-48TD 12.2(40)SE C3750E-UNIVERSALK9-M

Switch 01


Switch Uptime : 2 weeks, 4 days, 8 hours, 31 minutes

Base ethernet MAC Address : 00:1D:70:67:0D:00

Motherboard assembly number : 73-10315-12

Motherboard serial number : FDO12190321

Model revision number : E0

Motherboard revision number : B0

Model number : WS-C3750E-48TD-S

Daughterboard assembly number : 800-28590-01

Daughterboard serial number : FDO1216025L

System serial number : FDO1219R03T

Top assembly part number : 800-27544-04

Top assembly revision number : A0

Version ID : V02

CLEI Code Number : COM9V10ARA

License Level : ipbase

License Type : Permanent

Next reboot licensing Level : ipbase

Configuration register is 0xF



0001-zbran-3750a#sh license udi

Device# PID SN UDI


*2 WS-C3750E-48TD-S FDO1219V0FK WS-C3750E-48TD-S:FDO1219V0FK

1 WS-C3750E-48TD-S FDO1219R03T WS-C3750E-48TD-S:FDO1219R03T


vipul Thu, 09/10/2009 - 09:00

This may be an email-client issue.

Take a look into the license file for control characters at the beginning/end of the file. If there are some control characters, please delete them and try again.

MachadoGB Fri, 09/04/2009 - 11:15

Vipul can you check with Cisco is there are plans to simplify the license process for the 3750-E? any case related to that takes long time and bounce between TAC groups before comes to a solution and usually the answers are not clear.

Thank You.

vipul Thu, 09/10/2009 - 08:53

From a product standpoint, we have simplified the process (adding eval licenses, rehosting, emergency licenses) in 12.2(46)SE, and eliminated Advanced IP Services in 12.2(50)SE.

Anything else you'd like us to do to simplify things further?

mstyfernandez Mon, 09/07/2009 - 01:32


I have this switch:

"*2 26 WS-C3750-24FS 12.2(35)SE5 C3750-IPBASE-M"

that was a part of a stack of 3, however, the stack has been seperated using the 'no provision' command and all switches now know they are not stacked, but I am now configuring the switch that was #2 and it now thinks that it is the nominated master and all the interfaces still begin Fa2/0/1....Gi2/0/1.

I have deleted the original config.text and basically brought it back to scratch as far as I can or I know, but it still shows itself as switch #2:

"lection Complete

Switch 2 booting as Master

Waiting for Port download...Complete"

How can I make this switch back into #1?



vipul Tue, 09/08/2009 - 09:42

That is a good question, since the line is steadily blurring as more switches are able to route and more routers are able to switch. However, here are a few links I could find with a Google search that attempt to explain the classical difference between a switch and a router:

mailaglady2 Thu, 09/10/2009 - 10:33


I have a list of switches in the same family that I must test for different clients, now I need to know if my decision is not dangerous. below is the list of these boxes:













I want to test only one box per family (3500 and 3700) using the recent IOS and approve that IOS on all these boxes, my believe is the functionalities are the same the only diference is the additional ports, forwarding rate and the number of SFP's. am I right?

Leo Laohoo Mon, 09/07/2009 - 14:51

Use the command switch 1 renum and reload the switch.

Hope this helps.

talha_490 Mon, 09/07/2009 - 10:46

Dear Vipul,

I have few servers connected to 3750E swicthes. Those servers are the vmware servers. when i connect my pc to any other port i can see direct communication between those 2 servers.

If i will enable the sniffer on my computer and i am connected to the same swicth and same vlan i can see tnheir traffic.

there is no span configured on it. This is also the case with HP blade servers.

why does the swicth forwarding the traffic to all the ports.

vipul Thu, 09/10/2009 - 13:22

The simple answer is because the destination mac addresses for server packets has not been learned. Unknown destination macs are broadcast to all interfaces in the same vlan.

lxcollin1 Mon, 09/07/2009 - 21:22


Are there plans to introduce a CoPP feature on the 3750E? This is a critical feature that, to my knowledge, is not supported today.


dean.fitzpatrick Wed, 09/09/2009 - 10:29

Are the power supplies and fans in the RPS 2300 interchangeable with the E-series switches? How many switches do the RPSs power up? Is it following a first-come first-served algorithm in terms of how switches are powered?

vipul Wed, 09/09/2009 - 16:05

Are the power supplies and fans in the RPS 2300 interchangeable with the E-series switches?

Yes (the PoE power supplies only).

How many switches do the RPSs power up?

Connects to 6, powers up to 2, depending on the size and number of PSs in the RPS.

Is it following a first-come first-served algorithm in terms of how switches are powered?

Yes, unless you have RPS port priorities configured.

yagnesh_tel Thu, 09/10/2009 - 13:04


We used to have 3*3750 in stack in our network for quite sometime ago and we wanted to implement netflow on them. But we found that 3750 is not supporting this feature. This along with other capacity limitation eventually become reasons for replacing these stack with 6500. So I wonder if Cisco have started supporting netflow in newer versions or they are planning to?

vipul Thu, 09/10/2009 - 13:07

We cannot support netflow in the current gen Cat3xxx switches due to hardware limitations. What application were you looking to use a 3750 in that was replaced by a 6xxx?

John Blakley Thu, 09/10/2009 - 12:23

What's the easiest way to renumber switches?

Let's say I have 6 switches and they're all at the bottom of a rack. I want to add a seventh switch, but I have to add it to the top of the rack.

Instead of:








I'd want:








I've done the renumber before, but it really screwed up the config by not carring over the "new" port number with the old config. My 3/0/1 became 4/0/1, but 4/0/1 was an access port for a different vlan than 3/0/1 needed to be on, etc. It was a mess :)


Leo Laohoo Thu, 09/10/2009 - 15:17

Hi John,

In my humble opinion, there's no easy way to renumber a switch. I know how you felt because I've done the same mistake.

In my case, I made sure I do the "switch n provision" before I stick any switches in. Trying to renumber each and everyone of of the switches meant that I had to go through every switch port and make sure that they are in the correct VLANs. By the third stack of doing this hair-pulling exercise, I gave up and resigned my fate. If it was one done right the first time ...

vipul Fri, 09/11/2009 - 15:17

To avoid the problem of interface misconfigs, I suggest you copy the configuration file off the switch. Edit the config file by hand to move the interface configurations around as required. Then after the switches have been renumberd, copy the modified config file back to the stack. If the edits were done correctly, everything should be fine back to the way it was.

Another thought. What do you plan to do about the stack master? You probably still want member 1 to be master. If it gets renumbered to 2, will that be OK? Changing stack masters will require a reboot of the stack master, and modification of the switch member priorities.


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