Switch – No answer on arp requests

I have a problem where my Layer 3 Dell PowerConnect 6248 Switch (main switch) will sometimes (that means sometimes it works, sometimes it won't) not get an arp response from a device behind Dell PowerConnect 2824 (edge switch).

The situation

- - - - -       ===============          ===============       - - - - - 
| client | ---- | Main Switch | -------- | Edge switch | ----- | Device |
- - - - -       ===============          ===============       - - - - - 

1. If the Client is on same vlan as Device, there is no problem and traffic always flows.
2. If the Client is on different vlan, then only sometimes traffic will flow. This switch routes between vlans (inter-vlan routing).

3. Main switch broadcasts (many) arp packets, but seems like no response?!

   990 719.323028  Dell_xx:xx:xx   Broadcast   ARP Who has 10.11.0.43?  Tell 10.11.0.1
   

   because when looking at main switch's arp table, it doesn't know coressponding mac address:

   #show arp
   IP Address        MAC Address      Interface        Type        Age
   ---------------  -----------------  --------------  --------  -----------
   10.11.0.43       0000.0000.0000     vlan 11         Dynamic    0h  0m  2s
   

4. Main switch knows to which port
   traffic has to be sent to reach
   Device. There is an entry in address
   table that shows on which port the
   device is, the only problem is the
   switch doesn't know that particular
   IP corresponds to this MAC address
   🙁

   Address table:

   VLAN ID     MAC Address           Interface  
   VLAN 11     00:1c:c0:ef:e0:03       2/g5
   

5. Edge switch is L2 switch and it
   appears that address tables are ok
   for this switch also.

6. Some additional info about main switch:

   #show arp brief
   
   Age Time (seconds)............................. 1200
   Response Time (seconds)........................ 1
   Retries........................................ 4
   Cache Size..................................... 1024
   Dynamic Renew Mode ............................ Disable
   Total Entry Count Current / Peak .............. 68 / 99
   Static Entry Count Configured / Active / Max .. 6 / 6 / 64
   

Where is the problem?

Sometimes the traffic will just start flowing. Does the problem lie within the Main Switch or Edge Switch? Is it device configuration maybe? Maybe something with network cables? Main switch and edge switch is connected with fibre optics if it helps. Where should i look into?

Workaround

Creating a static arp entry solves the problem… currently I need only 5 arp entries for my devices, but this is just a workaround not a solution.