Duplicate IP Detected, Gratuitous ARP


I am trying to move our Polycom unit to its own VLAN to try and isolate/eliminate dropped packets. I changed the static IP address, subnet, and gateway on the Polycom out of the range of the existing Admin network.

I created the VLAN and tried to mimic what was already existing on the switch in terms of IP addresses and routes. I am able to navigate to the web gui of the Polycom and connect to make calls but I must have done something incorrectly as I am getting numerous Gratuitous ARP entries in Wireshark and the dropped packets remain.

Any help in troubleshooting this issues would be appreciated.

Here are some configuration outputs:

EXOS
show port 47 info detail
VLAN cfg:
Name: DistanceLearning, Internal Tag = 170, MAC-limit = No-limit, Virtual router: VR-Default

show port 48 info detail
VLAN cfg:
Name: DistanceLearning, Internal Tag = 170, MAC-limit = No-limit, Virtual router: VR-Default

show vlan
Admin 4091 172.16.0.254 /21 -f----------------------- ANY 118/182 VR-Default
Default 1 --------------------------------------------- ANY 0 /0 VR-Default
DistanceLearning 170 172.16.170.1 /24 ------------------------- ANY 2/2 VR-Default
Mgmt 4095 --------------------------------------------- ANY 0 /1 VR-Mgmt

show config
create vlan "DistanceLearning"
configure vlan DistanceLearning tag 170
configure vlan DistanceLearning add ports 2:47-48 untagged
configure iproute add default 172.16.0.1

show iproute
Ori Destination Gateway Mtr Flags VLAN Duration
#s Default Route 172.16.0.1 1 UG---S-um--f- Admin 24d:15h:18m:9s
#d 172.16.0.0/21 172.16.0.254 1 U------um--f- Admin 24d:15h:18m:22s
#d 172.16.170.0/24 172.16.170.1 1 U------um--f- DistanceLearning 1d:19h:31m:5s

Wireshark
3.893275000 Watchgua_d7:62:b8 MS-NLB-PhysServer-04_96:52:6b:7a ARP 60 Gratuitous ARP for 172.16.170.1 (Reply) (duplicate use of 172.16.170.1 detected!)
  • Address Resolution Protocol (request/gratuitous ARP)
  • Sender MAC address: MS-NLB-PhysServer-04_96:52:6b:7a (02:04:96:52:6b:7a)
  • Sender IP address: 172.16.170.1 (172.16.170.1)
  • Target MAC address: 00:00:00_00:00:00 (00:00:00:00:00:00)
  • Target IP address: 172.16.170.1 (172.16.170.1)

Firebox ARP
172.16.0.254 0x1 0x2 02:04:96:52:6b:7a * eth1
172.16.170.1 0x1 0x2 02:04:96:52:6b:7a * eth2

Diagram

3 replies

Userlevel 4
Not sure if I'm reading it wrong, but it looks like you have the same IP address defined at a virtual IP in the same VLAN (meaning the switch has .1 and the firewall has .1)...
Indeed, you are correct. Thanks for taking the time to review this issue.
Userlevel 4
Any time!

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