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Hannes
Asked: 2012-12-05 07:40:41 +0800 CST

servers connected to a poweredge 6248 receive traffic for their 'neighbours'

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In the network we have a few vlans but at the moment I was investigating vlan2 which carries the most traffic. When tcpdumping on the eth0.2 interface, I see a lot of packets arriving which are not addressed to, nor coming from the server. I checked this on several servers in the network and they all have the same issues.

In short, our switches don't switch the traffic but threat it like they are a hub. Can you tell me what settings on the dell poweredge 6248 should prevent this behaviour?

UPDATE:

I added some traffic I captured from the host. The ip address of the host is 192.168.3.232

192.168.3.248.80 > 192.168.62.102.26590:
192.168.3.232.35311 > 192.168.41.246.11211:
192.168.3.232.13412 > 192.168.19.200.3306:
192.168.3.232.35311 > 192.168.41.246.11211:
192.168.3.232.35311 > 192.168.41.246.11211:
192.168.3.234.12958 > 192.168.42.27.11211:
192.168.14.32.34077 > 192.168.19.200.3306:
192.168.3.232.36489 > 192.168.41.246.11211:
192.168.14.32.34077 > 192.168.19.200.3306:
192.168.14.9.42221 > 192.168.14.1.9312:
192.168.14.9.42221 > 192.168.14.1.9312:
192.168.14.9.42221 > 192.168.14.1.9312:
192.168.3.247.48542 > 192.168.41.37.11211:
192.168.3.235.9739 > 192.168.19.200.3306:
192.168.41.246.11211 > 192.168.3.232.36489:
192.168.3.232.36489 > 192.168.41.246.11211:
192.168.3.234.59715 > 192.168.41.199.11211:
192.168.14.32.34077 > 192.168.19.200.3306:
192.168.3.235.18919 > 192.168.42.12.11211:
192.168.25.122.7000 > 225.0.10.105.7000:
192.168.3.232.36489 > 192.168.41.246.11211:
192.168.3.236.43098 > 192.168.42.9.11211:
192.168.14.32.34077 > 192.168.19.200.3306:
192.168.3.236.43098 > 192.168.42.9.11211:
192.168.3.236.43098 > 192.168.42.9.11211:
192.168.11.84.4730 > 192.168.10.19.44335:
192.168.3.236.28328 > 192.168.42.11.11211:

dell

2 Answers

  1. Best Answer

    This sounds like a nasty bug I encountered on a pair of 5548's, which made the switches unable to learn new mac addresses after 49.7 days.. The symptom is that unicasts are sent out on all ports

    Devices stop to learn MAC addresses after 49.7 days

    After 49.7 days of operation, the device stops re-learning MAC addresses. These MACs which were previously learned will not appear in MAC address table. As a result traffic streams sent to previously learned MAC addresses are treated as unknown-unicast traffic and flooded within the VLAN.

    MAC address learning mechanism was fixed so that both learning new addresses and re-learning existing addresses are updating the MAC Address database.

    Reference: http://de.community.dell.com/techcenter/networking/w/wiki/308.firmware-55xx-firmware-v4-0-1-xx-features-und-fixes-englisch.aspx

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  2. The switches will filter only the frames for which the destination is in the MAC address table. This means that the traffic to unknown destinations, broadcast or multicast traffic will be send to all interfaces except the source interface.

    Now the question is: What is the real problem? As you should expect some broadcast traffic all the time (CDP, LLDP, BPDU...)

    • 1