Port 646: LDP
Port 646 is LDP, the Label Distribution Protocol that MPLS routers use to agree on the labels that steer traffic through a label-switched path. It is a core building block of carrier and large enterprise MPLS networks.
TCPRoutingUnencrypted by defaultIANA assigned
| Port number | 646 |
|---|---|
| Service | Label Distribution Protocol |
| Protocol | TCP |
| Category | Routing |
| Default encryption | No |
Security note. Port 646 is not encrypted by default. Restrict it to trusted networks, or use an encrypted alternative where one exists, to avoid exposing credentials and data in transit.
Frequently asked questions
What is port 646 used for?
Port 646 is LDP, the Label Distribution Protocol that MPLS routers use to agree on the labels that steer traffic through a label-switched path. It is a core building block of carrier and large enterprise MPLS networks.
Is port 646 TCP or UDP?
Port 646 (LDP) uses TCP.
Is port 646 secure?
Port 646 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 646 on my firewall?
Only if you specifically need LDP. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.