How do I configure a TenGig2/1 as Gig Uplink on a Cisco 4900M ( Module: ws-x4908-10g-rj45 )?

Question

Scenario:

We were swapping out Module 2 on a Cisco 4900M from a 20-Port Gig to a 8-Port TenGig, a ws-x4908-10g-rj45 be precise.

The hot swap went fine and TenGig2/1-8 sho ip int bri showed us the newly recognized ports, only that it wasn't just TenGig2/1-8, but rather TenGig2/1-8 - and - Gig2/9-16 (16 ports total).

4900M#sho ip interface  bri
Interface              IP-Address      OK? Method Status                Protocol
...
TenGigabitEthernet2/1  unassigned      YES unset  down                  down    
TenGigabitEthernet2/2  unassigned      YES unset  down                  down    
TenGigabitEthernet2/3  unassigned      YES unset  down                  down    
TenGigabitEthernet2/4  unassigned      YES unset  down                  down    
TenGigabitEthernet2/5  unassigned      YES unset  down                  down    
TenGigabitEthernet2/6  unassigned      YES unset  down                  down    
TenGigabitEthernet2/7  unassigned      YES unset  down                  down    
TenGigabitEthernet2/8  unassigned      YES unset  down                  down    
GigabitEthernet2/9     unassigned      YES unset  down                  down    
GigabitEthernet2/10    unassigned      YES unset  down                  down    
GigabitEthernet2/11    unassigned      YES unset  down                  down    
GigabitEthernet2/12    unassigned      YES unset  down                  down    
GigabitEthernet2/13    unassigned      YES unset  down                  down    
GigabitEthernet2/14    unassigned      YES unset  down                  down    
GigabitEthernet2/15    unassigned      YES unset  down                  down    
GigabitEthernet2/16    unassigned      YES unset  down                  down
...

---

Question:

How do I configure a TenGig2/1 as Gig Uplink?

I immediately notices that connecting the Uplink cable did nothing, no activity on the port indicator.

Went ahead and configured te2/1 anyway.

4900M(config)#int te2/1
4900M(config-if)#description Uplink to Router
4900M(config-if)#switchport access vlan 1
4900M(config-if)#switchport mode access
4900M(config-if)#l2protocol-tunnel cdp
4900M(config-if)#l2protocol-tunnel lldp
4900M(config-if)#l2protocol-tunnel stp
4900M(config-if)#l2protocol-tunnel vtp
4900M(config-if)#no cdp enable
4900M(config-if)#no shutdown

Still get no activity on the port...

4900M#sho int ten2/1 status
Port      Name                 Status       Vlan       Duplex  Speed Type
Te2/1     Uplink to Router     inactive     1            full   auto 10GBaseT

I figured that gi2/9 corresponds to te2/1 Gig functionality, since there is only 8 ports on this module, but it's displaying 16 total.

So, I configured gi2/9 too.

4900M(config)#int gi2/9
4900M(config-if)#description Uplink to Router
4900M(config-if)#switchport access vlan 1
4900M(config-if)#switchport mode access
4900M(config-if)#l2protocol-tunnel cdp
4900M(config-if)#l2protocol-tunnel lldp
4900M(config-if)#l2protocol-tunnel stp
4900M(config-if)#l2protocol-tunnel vtp
4900M(config-if)#no cdp enable
4900M(config-if)#no shutdown

And again, no activity on that port. We've tried swapping out the cable and have even done a reload for good measure.

How do I make that port an active Gig port for my uplink?

Answer 1

It took me some time, but I found the answer buried in documentation; where all the answers are, of course.

Short Answer:

4900M#conf t
4900M#(config)#hw-module module 2 port-group 1 select gigabitethernet

---

Explanation:

sho hw-module module 2 port-group will show you the Active port-group interfaces and their Inactive counterparts.

4900M#sho hw-module module 2 port-group
Module Port-group Active                         Inactive
-------------------------------------------------------------
   2        1     Te2/1-2                        Gi2/9-10                      
   2        2     Te2/3-4                        Gi2/11-12                     
   2        3     Te2/5-6                        Gi2/13-14                     
   2        4     Te2/7-8                        Gi2/15-16  

So, the module groups two ports together, in this case it's 1-2, 3-4, 5-6, and 7-8. You can select the port-group active interface from TenGig to Gig through hw-module module <#> port-group <#> select <port-group's int>.

4900M#(config)#hw-module module 2 port-group 1 select ?
  gigabitethernet     Select this port-group's gigabit interfaces
  tengigabitethernet  Select this port-group's 10G interfaces

For our needs, I changed module 2 port-group 1 selected interfaces from TenGig to Gig.

4900M#conf t
4900M#(config)#hw-module module 2 port-group 1 select gigabitethernet

Now I have an active connection for gig2/9.

4900M#sho int gi2/9 status
Port      Name               Status       Vlan       Duplex  Speed Type
Gi2/9     Uplink to Router   connected    1            full   1000 1000BaseT

And sho hw-module module 2 port-group shows the updated port-group's active interfaces:

4900M#sho hw-module module 2 port-group
Module Port-group Active                         Inactive
-------------------------------------------------------------
   2        1     Gi2/9-10                       Te2/1-2                       
   2        2     Te2/3-4                        Gi2/11-12                     
   2        3     Te2/5-6                        Gi2/13-14                     
   2        4     Te2/7-8                        Gi2/15-16 

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IMPORTANT NOTE: Gi2/9-10 are both set to Gig, so if you are only intending to use one Gig port, then you will still have to scarify two(2) TenGig ports to do so.