strange ARP problems in a stack og powerconnect 8164F

Question

Hi

i have a very strange behaviour of my powerconnect 8164 F.

I have the folowing topology

For level 2

level 2

level 3

For performance we would like to separate the traffic between level 2 and level3 that's why we have

created two LAG.

the LAG 1 should carry all vlan except the vlan 515

le lag 61 should carry only the vlan 515.

When the lag61 doesn't exist all is working ok.

But as soon as i created the LAG61 remove the vlan 515 from the lag1 and

configure the vlan 515 untagged on the LAG 61 i have the following problem.

Server A and server B are on the same vlan

they can ping each other.

Server WWW and server A can ping each other

But server WWW and server B can't ping each other.

the mac address of serveur B is in the mac adresse table of the dell

show mac address-table | include 427e
2 001E.8FDB.427E Dynamic Po1

The mac address is on the port channel 1 that is ok

but in the arp cache of the dell i have the following entry

195.83.222.25 0000.0000.0000 Vl2 Dynamic 0h 0m 0s

This entry stay for 5 secondes disappears and reappears.

in the arp cache of serveur A i have

kyocera1.genoscope.cns.fr (195.83.222.25) at 00:1E:8F:DB:42:7E [ether] on bond0

That s really puzzling

Why the serveur B isn't in the arp cache of the Dell wuth the proper mac address?

DELL-Josh Cr · Answer

Hi,   If they are all on VLAN 1 does the mac address of server B show correctly? Pings are sent at layer 2, so that is the topology that it should be following.

EricDoutreleau · Answer

There s no problem on level2. all computer that are on vlan 2 can see the server B it s only with computer that are on another vlan

DELL-Josh Cr · Answer

Are the 8164’s handling any routing or is it being done on the cisco? Is vlan 2 from server 2 to the 8164 configured as an access port on vlan 515?

EricDoutreleau · Answer

the Dell stack is routing the vlan 2. It has an ip adress on this vlan.

the vlan 4 is routing by the cisco

the vlan 515 is a vlan for interconnection between the cisco and the dell

the port channel 61 is configured in acces mode on the dell stack and in the cisco for the vlan 515

the port channel 1 is a trunk of all vlan except the 515

DELL-Josh Cr · Answer

Can you email me the running config? __@dell.com

EricDoutreleau · Answer

I have update the switches to the latest version of firmware

and now it seems to work correctly.

I guess here is the relating line on the changelog

Routing issue, null address in ARP table after VLAN manipulation
ARP replies destined to the DUT L3 MAC address will be dropped.
Corrected problem when removing ARP table entries
All 5.1 supported platforms

DELL-Josh Cr · Answer

That is great to hear. That will help anybody else with a similar problem.

Networking General

strange ARP problems in a stack og powerconnect 8164F

Was this post helpful?