CBS 220 - "uplink" meaning

[train_wreck]

Hello, I have a CBS 220 that has several VLANs configured on it. Port GE2 is configured as a trunk to CBS 250 switch, and the 250 has an identical VLAN configuration. This is working fine. I noticed in the web interface that there is an "Uplink" option on the VLANs. What does this do? At the moment it isn't checked, and the trunk appears to be working fine (e.g., untagged access ports that have the same VLAN ID are able to communicate across the switches.) Am I losing anything by not having it enabled? When should/shouldn't it be enabled? Thanks in advance.

[marce1000 · Accepted solution]

  Ref : https://www.cisco.com/c/en/us/td/docs/switches/lan/csbss/CBS220/Adminstration-Guide/cbs-220-admin-guide.pdf
>...(Available only in Trunk mode) If Uplink is enabled, select the TPID value for the
interface.

  Concerning the latter : A VLAN tag uses the tag protocol identifier (TPID) field to identify the protocol type of the tag. The value of this field, as defined in IEEE 802.1Q, is 0x8100.

                     Guess it is not needed to  change that in normal circumstances,

 M.

[train_wreck]

Yes I am reading more about the TPID setting. https://networkengineering.stackexchange.com/questions/19287/whats-the-difference-between-tpid-of-0x88a8-or-0x8100

QinQ format uses 0x8a88. I've got no need for that so I will keep the setting as it is. Thanks.