So I have a switch connected to ethernet cable which has a static IP address configured on it for IPv4 / v6. there are 3 IPv4 static addresses on its subnet.

I have 2 Anritsu callboxes connected to this switch which have been assigned static IPv4 /v6 addresses. However when both these callboxes are ON either one or both don't work. I mean they get IP addresses but cannot connect to the internet.

Why do I have this issue when I'm assigning static addresses to both these boxes?

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    You need to give us a lot more information. Please edit your question to at least give us a good network description/diagram, the network device models, and the network device configurations. Please refer to the Network Engineering Question Checklist for guidance, then edit your question to include enough information. – Ron Maupin Nov 14 '18 at 1:54
  • By the way, "ethernet cable" is far too broad. There are various grades of copper and fiber cables that can be used for ethernet, among other protocols, and the ethernet cable does not have an IP address; an interface may have an IP address if it is a layer-3 interface. – Ron Maupin Nov 14 '18 at 1:55
  • Hello Achillez and welcome. I'd suggest some straightforward network debugging questions: Can the three things on the local network ping each other? Can they ping something else in same IP network attached to another switch? Are they configured with a route (probably default route) to a router? Can they ping that router? – jonathanjo Nov 14 '18 at 11:59
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    Also, what makes you think IP collissions are the problem here? As @RonMaupin indicated, you need to provide a lot more details. – Teun Vink Nov 14 '18 at 12:03
  • What models are the Anritsu units? – jonathanjo Nov 14 '18 at 16:01

Assigning static, unique IP addresses to those devices rules out an IP address conflict.

However, some embedded device manufacturers use the exact same MAC address on every device of a type. Duplicate MAC addresses break L2 connectivity across a switch. Make sure both devices use different MAC addresses. Either

  1. Consult documentation or device labels for the MAC address.
  2. Check the switch's log and MAC address table for flapping addresses on the ports in question (requires a managed switch).
  3. ARP both static IP addresses. E.g. in Windows you could ping -n 1 <ipaddress> and arp -a <ipaddress>.

If this is in fact a MAC address conflict you'll need to change the MAC address on at least one of the device. If this isn't possible the boxes need to be connected to separate L2 segments/VLANs/broadcast domains.

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  • That looks good advice in general, however Anritsu doesn't look like the kind of organisation to do that, and according to wireshark has two OUIs (00:00:91, 00:02:b1) – jonathanjo Nov 14 '18 at 15:57

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