Power requirement for 3845 with two (2) switch modules

[rdauman24pb]

Hello,

I would like to know if any additional power would be needed for a 3845 (currently with one (1) NME-XD-48ES-2S-P) to which another 24-port switch module is added. Thus, I would have two (2) switch modules on the 3845 for a total of 72 ports.

I have been unable to find specific power requirements detailing the requirements with 1 ethernet module, 2, etc.

Your help is greatly appreciated!

Thanks,

Rob

[Amit Aneja]

What is the model no. of new module that are adding to the chassis?

show env all

show power inline

show inv

some add info if that solves your question.

The new Cisco EtherSwitch service modules (NME-16ES-1G-P,

NME-X-23ES-1G-P, NME-XD-24ES-1S-P, and NME-XD-48ES-2S-P only) can provide

both Cisco pre-standard and IEEE 802.3af Power over Ethernet (PoE) support

when inserted in Cisco 2800 Series or 3800 Series Integrated Services

Routers (requires an upgrade to an AC-IP power supply). 802.3af is the

IEEE standard for delivering power to Ethernet ports.

After you add 802.3af EtherSwitch modules, you might not be able to

configure PoE. This is because the inline power supply is required to

provide PoE capabilities in these routers. The external power supply

option cannot be used with the Cisco 2800 or 3800 Series. The internal

router power supply should be swapped out for a new power supply with PoE

capabilities if PoE is required. Examples of PoE enabled power supplies

include PWR-2811-AC-IP=, PWR-2821-51-AC-IP=, PWR-3825-AC-IP=, and

PWR-3845-AC-IP=.

[rdauman24pb]

Hello,

Thank you for your reply. I am looking to build a replacement for an existing 3845. The existing router has one (1)

NME-XD-48ES-2S-P; however, the new router needs to support more users so I am looking to add an additional 24-port module (NME-XD-24ES-1S-P).

I would like to know if I need to change any of the hardware (power supplies) in the chassis to support this additional 24-port card and/or if any additional power needs to be installed at the site to accommodate this new card.

Thank you.

Sincerely,

Robert Dauman

[Amit Aneja]

I don't think that these two NME would work in the same chassis.

Take a look at the following link, it clearly says that

NME-XD-24ES-1S-P wont be supported with any other NME.

http://www.cisco.com/en/US/customer/prod/collateral/routers/ps259/prod_qas0900aecd802a9470_ps5854_Products_Q_and_A_Item.html

Q. Can I install multiple Cisco EtherSwitch service modules in a chassis without configuring intra-chassis stacking?

A. Because each Cisco EtherSwitch service module is a separate, standalone switch, it is not necessary (nor is it supported) to configure intra-chassis stacking on these modules. With the exception of the StackWise module NME-XD-24ES-1S-P), you can install up to 2 EtherSwitch service modules in a single chassis. Because the StackWise supports Cisco StackWise interfaces, only one per chassis is supported.

Now, if you plan to use another NME-XD-48ES-2S-P in the same chassis & you have already installed PWR3845-AC-IP in the chassis, you should be good on the power front. You don't need any other power supply.

HTH,

Amit Aneja

[rdauman24pb]

Hello,

You seem to be saying - just to confirm - that if I can't have the NME-XD-48ES-2S-P and the NME-XD-24ES-1S-P in the same chassis; however, I can have two (2) NME-XD-48ES-2S-P SO LONG AS I HAVE a PWR3845-AC-IP installed and then I should be good for power - is that correct (I don't want to put words in your mouth! ).

If so, can you tell me how to confirm if I have the PWR3845-AC-IP to verify the power?

Thanks again for the help - much appreciated!

Rob

[Amit Aneja]

Rob,

NME-XD-48ES-2S-P and the NME-XD-24ES-1S-P cannot coexist in the same chassis. Infact,

NME-XD-24ES-1S-P won't work with any other NME in the same chassis. this is the only module with stacking ports, you could stack this NME with a 3750 switch.

If you have POE devices connected to NME-XD-48ES-2S-P already & they are powered up, that means AC-IP power supply is already installed in the chasiss.

You could chk the o/p of "show env", The o/p should look like below:

===============================

test3845_router#sh env

SYS PS1 is present.

        Fan status: Normal

        Input Voltage status: Normal

        DC Output Voltage status: Normal

        Type: AC

        Thermal status: Normal

AUX(-48V) PS1 is present.<<<<<<<<<<<<<<<<<<<

        Status: Normal

Compliance Mode: IEEE 802.af compliant

OR

yourname#sh env all

Main Power Supply is AC + IP<<<<<<<<<<<<<<<<<<<<<

================================

There is one more thing I want to highlight here i.e.Maximum PoE Delivery will be 360W.

Please take a look at the datasheet:

http://www.cisco.com/en/US/prod/collateral/routers/ps5855/product_data_sheet0900aecd8028d15f.html

Some imp points from the above datasheet:

Only one Cisco EtherSwitch service module per chassis is supported if NME-XD-24ES-1S-P is used;

otherwise up to two Cisco EtherSwitch service modules are supported per chassis where network module slot density allows

Additional PoE and switch ports can be added to the router with the Cisco EtherSwitch HWICs and network modules,

but the EtherSwitch HWICs cannot be stacked with the EtherSwitch service modules.

You can only utilize a maximum of two Cisco EtherSwitch service modules per chassis.

Four NME-16ES-1G-P or NME-XD-23-1G-P modules cannot be used in a Cisco 3845 or 3745 series router.

To maximize switch port density, two 48-port Cisco EtherSwitch service modules should be used on the Cisco 3845 series router.

Regards,

Amit Aneja

[rdauman24pb]

Thank you - this information is much appreciated!

[Amit Aneja]

Glad, I could help.

Please mark the post as answered if you do not have any follow up questions.

[rdauman24pb]

Hi Amit,

Before closing this ticket out, I just wanted to confirm one point regarding the AC-IP power supply. I see that the maximum PoE delivery is 360w. I assume this is with the AC-IP? Or, is this the maximum per NME-XD-48ES-2S-P. Based on the information you have provided, I plan to go with (2)  NME-XD-48ES-2S-P in my 3845; however, I just want to ensure that the I the AC-IP power supply is sufficient to support BOTH modules. Also, would the additional card necessitate any need for more power on-site to support this card or would it still fall within what the AC-IP could support?

Thanks again!

Rob

[Amit Aneja]

The maximum power delivery with AC-IP is 360W. This is not to power on the module, this power will be used to deliver POE to the devices connected to the NME. So, if you have IP phones connected to the NME, the total number of phones that can be powered up using this NME/AC-IP would be=

360/(Power per phone)

Now, there are IP phones or Access point models which consume from 7.x to 15.4 watts.

If you aren't connecting any POE devices to the NME, then it will work just fine, we don't need to think about power in that case.

HTH,

Amit

[rdauman24pb]

Hi Amit,

I looked at my existing 3845 (which I will be replacing with a new 3845) and did a "show power inline" and see that my 7961s are using 6.3w.

So, from what you are saying, the 360w is the total supported by the AC-IP power supply - irrespective of how many

NME-XD-48ES-2S-P I install (1 or 2). Would I be correct, then, that based on 6.3w I would be OK to install 2

NME-XD-48ES-2S-P fully populated with phones (hypothetically), as this would be 6.3 * 48 = 302.4 - less than the 360w total for the AC-IP.

Thanks!

Rob

[Amit Aneja]

Yes, what you are saying is right. I guess 50-55 is the no. of phones(6.3W) that will work with AC-IP power supply.

[rdauman24pb]

Hi Amit,

The requirements for the site are > 50 users, so I plan on installing (2) NME-XD-48ES-2S-P. It seems the AC-IP with its 360w maximum caps me at about 50-55 phones based on the wattage I saw on existing routers (6.3w). Should I need more phones, does the 3845 hold more than one (1) AC-IP power supply or, if more phones are needed, is another router the only solution?

Thanks,

Rob

[Amit Aneja · Accepted solution]

Rob,

two power supplies would be supported but only for redundancy, they won't work in combined mode so as to provide 360W+360W.

The best I can think of in your scenario would be to use the other NME module i.e.NME-XD-24ES-1S-P if you have a 3750 switch as well. We can stack this NME with the 3750 switch & they work as one unit. Don't know if you have a 3750 or not, whether that's a feasible option for you or not.

However, 3845 won't support more than 360W.

Regards,

Amit

[Amit Aneja]

Rob,

thanks for the ratings.

Regards,

Amit