New SmartHub 2 Router Broadcasting STP Packet storm - Home Solution

[sentinel_watcher]

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

[StuartHK]

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

[sentinel_watcher]

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

[Crimliar]

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