- Shut down interfaces before configuring (best practice on ME3400)
- No DTP — dynamic trunk negotiation does not exist
- No VTP — VLAN Trunking Protocol does not exist
- Default STP mode is PVST
- Typically deployed as the last hop (service provider edge / CPE)
- Port model is based on port-types and UNI VLANs rather than standard IOS switchport modes
- Connects to customer end devices (phones, computers, routers at the customer site)
- All ports except uplinks default to UNI
- Can only forward traffic toward NNI ports
- No STP
- No CDP
- No Link Aggregation
- Connects to routers or switches (slightly trusted devices)
- Supports STP
- Supports CDP
- Supports Link Aggregation
- Network-to-Network — connects to other provider nodes/uplinks
- No Layer 2 protocol filtering — passes BPDUs, CDP, etc. transparently
| Feature | UNI | ENI | NNI |
|---|
| STP | ✗ | ✓ | ✓ |
| CDP | ✗ | ✓ | ✓ |
| Link Aggregation | ✗ | ✓ | ✓ |
| L2 Protocol Filtering | ✓ | ✓ | ✗ |
| Customer-facing | ✓ | ✓ | ✗ |