1

I have a switch HPE 1920-8G-PoE+ that is connected to two computers and two access points: Ubiquiti UniFi AP-Pro n450.

The access points receive data from many devices. The two computers send UDP segments to these devices (to the specific IP address) and exchange UDP segments between them (multicast address). The IP address of the wireless devices are in a known range.

Is there a way to filter the multicast UDP segments that are sent to the two access points? In other words I would like to configure the two ethernet ports used by the access points in such a way that they block all the multicast traffic which is not destined for the wireless devices.

Improve this question
2
  • I updated your question to be more on target. I also updated my answer.
    – Ron Maupin ♦
    Feb 27, 2016 at 23:30
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin ♦
    Aug 7, 2017 at 20:08

1 Answer 1

Reset to default
1

Switches are not like hubs. Hubs repeat every frame out every port. Switches selectively send the layer-2 frames to the port where the receiving host is connected.

Switches are layer-2 devices, so they only look at the layer-2 frames, not the layer-3 (IP, etc.) packets, or the layer-4 (TCP, UDP, etc.) segments. Switches learn the MAC addresses which are connected on each port from the traffic through each port, and they only send frames destined for a MAC address on a port to that port. Switches will flood broadcast frames to every port (but that's the point of a broadcast, it is destined to every host on the broadcast domain), as well as unicasts which are not yet in its MAC address table.

The HPE 1920-8G-PoE+ is also a layer-3 switch. Layer-3 is where you will find IP packets, but layer-3 routing only sends IP packets to the ports which have the network of the destination IP address.

You didn't include any configuration, but I seriously doubt you have a problem with traffic which is not destined to a host connected to your WAPs traveling to your WAPs.

Edit:

Based on your comment about this being multicast, you need to use IGMP snooping to deal with your problem. Multicast frames, like broadcast frames, are usually sent to all switch ports in the same broadcast domain. IGMP snooping lets a switch snoop on IGMP messages to determine which switch ports should receive frames for which multicast groups. Your switch supports IGMP snooping:

  • IGMP snooping

improves network performance through multicast filtering, instead of flooding traffic to all ports

You could also break up your layer-2 broadcast domain with VLANs.

Improve this answer
3
  • Thanks for the explanation. The problem is that the two computers sends UDP packets over a multicast address. I would like to avoid this to be sent to the access point. That why I would like the access point to receive only UDP packets that are sent to a specific IP range
    – Maverik
    Feb 27, 2016 at 23:14
  • I updated the question
    – Maverik
    Feb 27, 2016 at 23:15
  • 1
    You need to forget about layer-3 packets and layer-4 segments in the same layer-2 domain. Multicast is different; it is a form of broadcast. You need IGMP snooping. That lets the switch snoop on IGMP messages between the multicast clients and the multicast router. It will then send multicast frames to only those switch ports where there is a client which has subscribed to the multicast group. Also, you need to understand that multicast MAC addresses map to 32 different multicast IP addresses. The other option is to set up Wi-Fi and ethernet on different VLANs.
    – Ron Maupin ♦
    Feb 27, 2016 at 23:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.