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Ask the Expert- SD-WAN

3850: Understanding interface configuration on NM modules

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Introduction

It is sometimes confusing on which interfaces are available and which can be configured when using one of the NM modules in a Cisco 3850 Switch.  We currently offer three different modules:

  • C3850-NM-4-1G (four 1-Gigabit SFP module slots)
  • C3850-NM-2-10G (Combination of 1-Gig and 10-Gig ports)
  • C3850-NM-4-10G (four 10-Gigabit slots or four 1-Gigabit slots)

The available configuration is based on which model NM you are using.  The intent of this document is to help clear up some of the misunderstood configuration options.  Below are details on each NM module and how to configure each one when inserted into the switch.

 

344199.jpg

 

C3850-NM-4-1G

This module has four 1-Gigabit SFP module slots. Any combination of standard SFP modules are supported. SFP+ modules are not supported.  If you insert an SFP+ module in the 1-Gigabit network module, the SFP+ module does not operate, and the switch logs an error message.

C3850-NM-2-10G

This module has four slots that support the following combinations:

Two slots (left side) support only 1-Gigabit SFP modules and two slots (right side) support either 1-Gigabit SFP or 10-Gigabit SFP modules.

Three slots (left side) support 1-Gigabit SFP modules and one slot (right side) supports 10-Gigabit Ethernet SFP+.

Supported combinations of SFP and SFP+ modules:

Slots 1, 2, 3, and 4 populated with 1-Gigabit SFP modules.

Slots 1 and 2 populated with 1-Gigabit SFP modules, and Slot 4 populated with one 10-Gigabit SFP+ module.

Slot 3 and Slot 4 each populated with 10-Gigabit SFP+ modules.

C3850-NM-4-10G

This module has four 10-Gigabit slots or four 1-Gigabit slots.

Note This is only supported on the 48-port models.

Configuration

For the C3850-NM-4-1G module - All ports are natively Gig and are configured as Gig1/1/1 through Gig1/1/4

<snippet>

interface GigabitEthernet1/1/1 <-------- Config this interface
!
interface GigabitEthernet1/1/2 <-------- Config this interface
!
interface GigabitEthernet1/1/3 <-------- Config this interface
!
interface GigabitEthernet1/1/4 <-------- Config this interface
!
interface TenGigabitEthernet1/1/1 <-------- Disregard
!
interface TenGigabitEthernet1/1/2 <-------- Disregard
!
interface TenGigabitEthernet1/1/3 <-------- Disregard
!
interface TenGigabitEthernet1/1/4 <-------- Disregard

For the C3850-NM-4-10G module - All ports default to 10G and should be configured as
TenGig1/1/1 through TenGig1/1/4 - even though you are operating them as 1G via SFPs.

<snippet>

interface GigabitEthernet1/1/1 <-------- Disregard
!
interface GigabitEthernet1/1/2 <-------- Disregard
!
interface GigabitEthernet1/1/3 <-------- Disregard
!
interface GigabitEthernet1/1/4 <-------- Disregard
!
interface TenGigabitEthernet1/1/1 <-------- Config this interface
!
interface TenGigabitEthernet1/1/2 <-------- Config this interface
!
interface TenGigabitEthernet1/1/3 <-------- Config this interface
!
interface TenGigabitEthernet1/1/4 <-------- Config this interface

For the C3850-NM-2-10G module - The first two ports are natively 1G ports and the last two ports
are natively 10G ports. So you configure the 1Gig ports as Gig1/1/1 through Gig1/1/2, and configure the
last two ports as TenGig1/1/3 through TenGig1/1/4 - even if you are operating the last two ports as 1G.

## This is commonly misunderstood ##

<snippet>

interface GigabitEthernet1/1/1 <-------- Config this interface
!
interface GigabitEthernet1/1/2 <-------- Config this interface
!
interface GigabitEthernet1/1/3 <-------- Disregard
!
interface GigabitEthernet1/1/4 <-------- Disregard
!
interface TenGigabitEthernet1/1/1 <-------- Disregard
!
interface TenGigabitEthernet1/1/2 <-------- Disregard
!
interface TenGigabitEthernet1/1/3 <-------- Config this interface even if using 1G
!
interface TenGigabitEthernet1/1/4 <-------- Config this interface even if using 1G

** There are only 4 interfaces which are valid and the other 4 should not be used even though they still show up in the CLI

Supported GBICs

TenGig

  • SFP-H10GB-CU1M
  • SFP-H10GB-CU3M
  • SFP-H10GB-CU5M
  • SFP-10G-SR
  • SFP-10G-LRM
  • SFP-10G-LR
  • SFP-10G-ER

OneGig

  • GLC-T (10/100/1000)
  • GLC-SX-MM
  • GLC-LH-SM
  • GLC-SX-MMD
  • GLC-LH-SMD
  • GLC-ZX-SM
  • GLC-ZX-SMD
  • GLC-BX-D
  • GLC-BX-U
  • CWDM SFP
  • SFP-GE-S
  • SFP-GE-L
  • SFP-GE-Z
  • DWDM SFP
  • DWDM SFP (add.)

Reference

  • Installing a Network Module

http://www.cisco.com/en/US/docs/switches/lan/catalyst3850/hardware/installation/guide/HIGNM.html#wp1053282

  • 10-Gigabit Ethernet Transceiver Modules Compatibility Matrix

http://www.cisco.com/en/US/docs/interfaces_modules/transceiver_modules/compatibility/matrix/OL_6974.html

  • Cisco Gigabit Ethernet Transceiver Modules Compatibility Matrix

http://www.cisco.com/en/US/docs/interfaces_modules/transceiver_modules/compatibility/matrix/OL_6981.html#wp166237

Comments
Beginner
Beginner

Hi Benjamin, did you find an answer ? I Have the same issue... thks

Beginner

I have exactly the same problem.

Seems that the last version of the compatibility matrix (updated Dec 05, 2016) stil does not contain info about C3850-NM-4-10G

Beginner

Hi,

i also need 1G SFP compatibility with C3850-NM-4-10G and C3850-NM-2-10G

anyone can help?

Beginner

Hi Peter,

Did you get an answer to this? I need exactly the same configuration (2x GLC-TE and 2x SFP-10G-SR-S) on a C3850-NM-4-10G. This is helpful as a stopgap on the way to 4x 10G.

The datasheet implies this is possible, but the 1Gbit compatibility list fails to mention the NM-4-10G (it does mention the C3850-NM-8-10G however):

http://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/compatibility/matrix/GE_Tx_Matrix.html

Regards

James.

Beginner

Hi James,

I saw the following in the datasheet so assume we can mix 1G and 10G on 4-port 10G module. Regarding compatibility, if you searched for an older version of the matrix you can find the NM-4-10G and GLC-T. I think the new doc needs to be updated.

An SFP+ receptacle supports both 10 Gigabit Ethernet and Gigabit Ethernet modules, allowing customers to use their investment in Gigabit Ethernet SFP modules and upgrade to 10 Gigabit Ethernet when business demands change without having to do a comprehensive upgrade of the access switch. In contrast, SFP receptacles can be used only as Gigabit Ethernet ports, as shown in the examples in Table 4.

Table 4.       Network Module Configuration Examples

 

Interface Options

Network Module

10 Gigabit Ethernet SFP+ Ports

Gigabit Ethernet SFP Ports

4 x Gigabit Ethernet

0

4

4 x Gigabit Ethernet/2 x10 Gigabit Ethernet network modules

2

0

1

3

2

2

0

4

4 x Gigabit Ethernet/4 x10 Gigabit Ethernet network modules

4

0

0

4

2

2

3

1

1

3

Enthusiast

Hi There,

i can see C3850-NM-4-10G is now supported with WS-C3850-12XS switch, and can i connect GLC-SX-MMD= for that module?

thank you

Community Member

Hi Kasun,

Check out here http://www.cisco.com/c/en/us/support/interfaces-modules/transceiver-modules/tsd-products-support-series-home.html for all supported optics for all Cisco switches

Regards,

Eugenios

Enthusiast

Hi Eugenios,

thanks for the link. i have checked it but its not shows C3850-NM-4-10G in the gigabit transceiver list. i just wanted to make sure that module support GLC-SX-MMD

thank you

Beginner

I had a situation where someone not familiar with the module added a 1 gig SFP to a C3850-NM-2-10G that already had 2 TenGig uplinks. The switch accepted the 1+10+10 configuration without complaining. However, interface T1/1/3 started getting high input error rates. It took a while to figure it out the problem because the module limitations weren't fresh in anyone's mind.   Now, I put a description on all the interfaces that aren't supposed to be used.

Gi2/1/1   admin down    down   DO NOT USE IF USING Te2/1/3 and Te2/1/4
Gi2/1/2   admin down    down   DO NOT USE IF USING Te2/1/3 and Te2/1/4
Gi2/1/3   admin down    down   DO NOT USE IF USING Te2/1/3 and Te2/1/4
Gi2/1/4   admin down    down   DO NOT USE IF USING Te2/1/3 and Te2/1/4
Te2/1/1   admin down    down   DO NOT USE IF USING Te2/1/3 and Te2/1/4
Te2/1/2   admin down    down   DO NOT USE IF USING Te2/1/3 and Te2/1/4
Te2/1/3   up                   up        UPLINK to Fabric Interconnect A - int Eth 1/2
Te2/1/4   up                   up        UPLINK to Fabric Interconnect B - int Eth 1/2

Dear All,

 

Please i would like to know if C3850-NM-8-10G can be used as a downlink port to some access switches (WS3650-24PD/K9 the uplink port) 

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