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rootdet
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Joined: Thu Jun 17, 2010 6:21 pm

Arp Issues

Wed May 19, 2021 8:06 pm

Hi all,

FYI, i made a support case for this as well last week, but have yet to get any real response. So i am posting this here in hopes of the community having some ideas to try.

We were using firmware 6.47 on the stable release for both the CCR1072 and the CRS309. The system was fully functional before. After upgrading to the newest stable version AND trying the beta firmware, we experience an issue where the CCR1072 does not learn MAC addresses.

After patching we noticed that pinging between vlans on items that sit off the HPE Aruba and CRS309 could not happen. We also notice that nothing was pingable coming from VLAN 700 (HP Core). I verified routing, verified interfaces (physical, vlan, bride and bond) were set to running and showed link where applicable.

I tested pings from the CCR1072 and CRS309 and confirmed that pings mostly did not work (99% failure). However CRS1072 and CRS309 could ping each other on vlan 400. Vlan 400 and vlan 300 seemed unaffected by the problems. I disabled VRRP and moved the default gateway IP to the vlan itself to take VRRP out of the equation. No joy.

I expanded my search to add a Layer 3 interface (temporarily) t the CRS309 and the HPE switch bellow on vlans 116 and 113 for testing. My purpose was to try and ping the endpoints i could not get to over Layer 2/3 routing via CRS1072. I found that these devices could ping devices just fine. however the CCR1072 could NOT ping the L3 Ip’s i added t the switches. Checking of the ARP table (/ip arp) shoes these IP’s were set to dynamic and no MAC address was found. I let the pings go for about 20 rounds and sitll no ARP resolution.

Once i initiated a ping from the HPE and CRS309 to the IP of the CCR1072 (Rather it be VRRP or the non VRRPIP), the AMC address now appeared in the ARP table, after the 1st ping failed. Subsequently, the CCR1072 would now be able to ping the devices. If i changed the IP on the switches and tried to ping the new IP again from the CCR, Ping failure. Start a Ping from the switch to the CCR, MAc is now in ARP, and CCR will be able to ping the switch.

I brought this test further and tested physical hardware that sat bellow the HPE. Again the Mikrotik could not ping it, but once i iniated traffic from that device to the CCR (or through the CCR to the outside world), the device was now fully accessible to the CCR and to the rest of the network from other vlans.

My next test was to use the switches to ping the devices and check it;s ARP table to get the MAC address. I took this MAC address and manually added a static entry to the CCR1072 ARP table. Before i did this the device was not pingable from the CCR but was pingable from the switches. After adding the static ARP entry, the device can ping. I was able to rinse and repeat this with about 10 different IPs.

I verified where possible on the CRS309 and cRS1072 that ARP is enabled on all interfaces, bridges, bonds, vlans, etc. I even change where applicable from “auto” to yes. Still, this made no difference in arp discovery.

AS of right now we must manually static ARP EVERY device in vlan 112, 113, 114, 115, 116. I did try going from stable to beta firmware on the devices but the issue persists. So either the issue impacts multiple firmware versions and i need to downgrade to long-term release, or there is another problem. I have not manually tied going back to 6.47 because I have had no luck with manual firmware updates via package manager.
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