You can enable gig ports on SCM but user traffic may stop for several tens of seconds.
I confirmed the behavior with my lab devices.
--- interface config on CSS
interface 1/1
admin-shutdown
bridge vlan 774
interface 1/2
admin-shutdown
bridge vlan 775
interface 2/1
bridge vlan 774
interface 2/2
bridge vlan 775
---
When I enabled (issued no admin-shut) at interface 1/1 and 1/2, bridge forwarding table
was purged and all services went down.
After several tens of seconds, all client and server mac address were listed on bridge
forwarding table and all services went alive. (Console log of my test is attached.)
---
CSS11503-A# show bridge forwarding
VLAN MAC Address Port Number
----- ----------- -----------
VLAN774 00-1d-45-26-87-17 2/1
VLAN775 00-0c-29-21-d7-62 2/2
00-0c-29-2f-15-7b 2/2
00-1d-45-26-87-18 2/2
00-0c-29-68-3e-de 2/2
CSS11503-A# show service summary
Service Name State Conn Weight Avg State
Load Transitions
sv1 Alive 0 1 2 34
sv2 Alive 0 1 2 32
sv3 Alive 1 1 2 38
CSS11503-A# conf t
CSS11503-A(config)# int 1/1
CSS11503-A(config-if[ 1/1])# no admin-shutdown
CSS11503-A(config-if[ 1/1])# int 1/2
CSS11503-A(config-if[ 1/2])# no admin-shutdown
CSS11503-A(config-if[ 1/2])#
CSS11503-A# show service summary
Service Name State Conn Weight Avg State
Load Transitions
sv1 Down 0 1 255 35
sv2 Down 0 1 255 33
sv3 Alive 0 1 2 40
CSS11503-A# show bridge forwarding
VLAN MAC Address Port Number
----- ----------- -----------
VLAN774 00-0c-29-56-32-91 1/1
00-1d-45-26-87-17 2/1
VLAN775 00-0c-29-21-d7-62 1/2
---
I mean that you can connect between cat3750 and CSS with GBIC and fiber cable.
However, communication failure may occur during this operation. (Maintenance window
wil be needed.)
