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New SmartHub 2 Router Broadcasting STP Packet storm - Home Solution

sentinel_watcher — Thu, 27 Mar 2025 10:32:24 GMT

Recently upgraded from BT Home Hub 5 to Smart Hub 2 for new BT Digital voice and after installing SH2 noticed large broadcast storms by using Wireshark on home PC network. There were 10 x STP broadcast frames every 3 seconds and filling Wireshark output. These were coming from the BT Smart Hub MAC address which uses an Arcadyn PHY MAC 44fe.3b76.aa88 sent as broadcast to 0180.c2ef.03fe

Just sharing how I stopped this LAN STP broadcast frames by using a MAC ACL on the ingress port to Cisco switch from BT router. After applying Wireshark stopped seeing L2 Arcadyn frames and all normal Layer 3 networking/web access was still working fine and network traffic level much calmer.

Stopped BT Arcadyn Broadcast STP Filtering on Cisco 2960L by MAC ACL

mac access-list extended drop_arcadyn

deny host 44fe.3b76.aa88 host 0180.c2ef.03fe

permit any any

Snippet of Cisco_Home 2960L port config to BT router, with additional MAc access-group :

interface GigabitEthernet0/24

description == BT Home Hub router ====

switchport access vlan 34

switchport mode access

mac access-group drop_arcadyn in

arp timeout 270

spanning-tree portfast edge

spanning-tree guard root

Re: New SmartHub 2 Router Broadcasting STP Packet storm - Home Solution

StuartHK — Sat, 05 Apr 2025 18:34:19 GMT

Wouldn't it be easier just to resolve the switching loop?

Re: New SmartHub 2 Router Broadcasting STP Packet storm - Home Solution

sentinel_watcher — Tue, 08 Apr 2025 13:23:27 GMT

There is "No" switching loop in the network, never has been. The broadcast STP for bridges packets are being purely injected by the Smart Hub 2 (SH2),as soon as I added to my home network replacing the older HH5, hence why I have blocked them at ingress.

Hopefully a future Smart Hub (aka Arcadyan) firmware release by BT will stop these :

BT Smarthub LAN broadcast packets 2025

Re: New SmartHub 2 Router Broadcasting STP Packet storm - Home Solution

Crimliar — Tue, 08 Apr 2025 15:19:03 GMT

I don't see 10 packets every 3 seconds as a network storm. It's more than you would expect but not significantly so.