SSDP and CISCO C9610 / C9350

A number of our products, including but not limited to the list below, use SSDP (Simple Service Discovery Protocol) to automatically find each other on the network. Some switches might block SSDP by default.

- ALIF1100, ALIF2100, ALIF4000, ALIF102T
- AVM
- XDIP

On the Cisco C9350 switch, SSDP forwarding requires the following global command:

platform ip multicast ssdp

This command is found in Cisco’s IP Multicast Routing Configuration Guide. The guide states that -+239.255.255.250+- is blocked by default on the C9610 and requires this command. The same behavior applies to the C9350.

The documentation trail is somewhat confusing:

• August 8, 2025: IOS XE 17.18.1 was released, and the command is present but undocumented.
• September 2025: Cisco’s multicast guide documented the requirement for the C9610, but did not mention the C9350.
• April 2026: The C9350 IOS XE 26.1.1a release notes explicitly documented the -+ssdp+- keyword as a behavior change.

Because SSDP was disabled as an implicit platform default, there was no ACL, VACL, or other blocking statement visible in the switch configuration. The platform discards SSDP before it reached the switch’s embedded packet-capture path, which also explains why captures on the endpoint-facing interfaces show no UDP/1900 traffic.