Apple Devices Casuing intermittent network outages

[Thomas_Randolph]

We have recently started rolling Apple devices at one of our locations. Approximately 1200 iPads. They are connecting to via an Aerohive wireless solution. That solution has 1 point of entry to my network at a B5 switch that is also doing layer 3 for that site to our WAN. When the iPads starting ramping up, it has seemed to cause frequent intermittent network outages. Devices on the rest of lan in different vlans stop communicating and then will come back within 5-10 seconds. This happens anywhere from 1-50 minutes during every hour of the day including overnight when no users are onsite. After extensive troubleshooting, we still have not identified the cause of the problem but believe it is possibly something with the B5G124-48P2. From one of my switches at the local site, when the problem happens, I cannot reach my default gateway, which is the IP address of that vlan interface configured on the B5. Since affects all vlans, we suspect the B5. The routing is all static and RIP is disabled. Also when this is happening, the system CPU is not excessive, it is usually around 26-45% but I have seen it spike very shortly up to 60-80%. I have debug logging enable and the have no logs indicating that system resources are taxed. The only recurring log entry I get is "DHCPRELAY[265701448]: relay_main.c(315) 568089 This is from manager 1 %% Request could not be relayed to Server". I have also checked my DHCP server, however it is supporting all 14 of my sites with no issues anywhere else. I checked the mac tables and we usually sit at just under 4000 entries, but according to the specs for the B5 it can support up to 24,000. I appreciate any help or suggestions.

[Bill_Handler]

Just to chime in on the information already provided with an additional possibility/question...

Is it possible that there is an IP conflict? We chased an issue at a customer site for months. Our situation was slightly different, but had a similar impact.

There was a BYOD that would come on the network (iPad) that would keep it's DHCP address from their home network. The device would not relinquish the IP for a few cycles, even though it was connected to the wireless with a different IP space.

As an unfortunate coincidence, the IP that this device would not relinquish happened to be the IP address of the gateway. As a result, this poisoned the ARP tables on a few devices and caused devices to not be able to reach the gateway...

[Thomas_Randolph]

That is definitely a weird one, however our problem persist through the night with no users onsite. Our users are also not allowed to take iPads offsite. I do have a GTAC case open, but wanted to cover my bases with the community help. Thanks.

[Jason_Parker]

I do agree that you may want to reach out to the GTAC and open a ticket I would would be glad to assist if needed Let's start with a quick use toon Does the AP support -pause frames? To find out from the switch cli run the command show port advertise and look for pause under the remote section If a Yes is seen then the AP supports Pause So if yes, then run the command Show port flowControl port# or show txwmonitor flowControl port# If the ports show rx #'s, then there is more likely that the AP may be overwhelmed or if feels that the load along with some unwanted traffic it is processing traffic(may be multicast ) or maybe a small change on the switches config is needed) GTAC can assist An option ( if there are numbers that increment) as a workaround: You may have to run this command: warning : The command will drop the link, clear the option to advertise the port supports pause (Default on all Ports)and then negotiate speed/duplex Clear port advertise port# pause Now check you connection Here is an article that may help you: https://gtacknowledge.extremenetworks.com/pkb_mobile#/articles/en_US/Solution/Slow-Performance-on-SecureStack-or-random-loss-of-connection-to-neighboring-switch Jason Parker

[Thomas_Randolph]

Thanks for the info. The Aerohive APs are not attached to the B5, Aerohive just hands off to us on a copper gig port from their switch. It is a managed wireless solution. I did check the advertise status and it shows no for everything on all the 1000Base-T ports.

[Jeremy_Gibbs]

Have you checked port counters? Do a show rmon stats ge.1.9 for example to look at that port. However, I would take a look at your uplink first. Also, have you checked spanning-tree? Run show spantree stats active and show spantree stats. Do you see any topology changes when this is happening? If you are using 802.1d and the network has to reconverge because of some spantree event, it could take several seconds up to 40-50 seconds to stabilize.