Cisco CLI Random Interfaces?

[JB-TX]

Purchased a C3850-12X48U (1G, 10G, 40G) Along with a 10G Fiber Upload 8 port module.

There are some random interfaces that are not physical on the switches CLI. Can anyone shed some light for me?

interface TenGigabitEthernet1/0/44 <--- Physical
!
interface TenGigabitEthernet1/0/45 <--- Physical
!
interface TenGigabitEthernet1/0/46 <--- Physical
!
interface TenGigabitEthernet1/0/47 <--- Physical
!
interface TenGigabitEthernet1/0/48 <--- Physical
!
interface GigabitEthernet1/1/1 <---???
!
interface GigabitEthernet1/1/2 <---???
!
interface GigabitEthernet1/1/3 <---???
!
interface GigabitEthernet1/1/4 <---???
!
interface TenGigabitEthernet1/1/1 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/2 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/3 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/4 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/5 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/6 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/7 <--- Physical Uplink Module
!
interface TenGigabitEthernet1/1/8 <--- Physical Uplink Module
!
interface FortyGigabitEthernet1/1/1 <---???
!
interface FortyGigabitEthernet1/1/2 <---???

[balaji.bandi]

The expansion module is mGig ( means multi-gig capabilities).

[JB-TX]

---

@balaji.bandi wrote:

The expansion module is mGig ( means multi-gig capabilities).

---

I don't believe the module is a mGig. It specifically says 10G on Cisco datasheet. The switch has mGig capabilities. I could be wrong though. Regardless how does that explain the extra interfaces? There is no physical port for them.

[craigshawm6]

Those are in the config in the event you installed the 4x1gb network module or the 2x40gb module instead of the 8x10gb you currently have. All potential available port names are hardcoded into the config. (so 1 config/code regardless of what module you purchase/install) Only the physical ports/modules you installed will need to be configured. You can configure/shut those down if you'd like.

[vb10]

Hello,

Usually, additional interfaces might appear, if Network Module has interfaces, capable to operate at different speed. For example, C3850-NM-2-40G will have 2xFortyGig interfaces and 8xTenGig in config, and you configure interfaces, depends on whether you use breakout cable or not.

In your particular case, if you have module C3850-NM-8-10G, it should have all the interfaces working at 10G by default, so it should have only interfaces Te1/1/1-8.

It's hard to say, why there are other interfaces in the list in case of C3850-NM-8-10G module. It might be cosmetic bug, or another modules were installed into the slot previously, and these interfaces somehow were not cleared

Additional information can be found in this article, section Network Module Port Configurations section

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/hardware/installation/guide/b_c3850_hig/b_c3850_hig_chapter_011.html

[craigshawm6 · Accepted solution]

In both the 3850x and the 2960x, all the interfaces were listed in the config, regardless of network module installed. (2960x would show Gig1/1/1 and TeGig1/1/1) but only need to config the actual interfaces present with your network module. The non-existent interfaces are not virtual, they are just presets(placeholders) in the config in the event the corresponding module is used. You have no need to worry about them.