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325
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arp entry for same mac

suthomas1
Level 6
Level 6

Hello,

Following is seen on a switch which has layer 3 for vlan 11.

sh ip arp | i 7af2
Internet  192.168.96.145         42   50bd.9dc4.7af2  ARPA   Vlan11
Internet  192.168.96.52          43   50bd.9dc4.7af2  ARPA   Vlan11
Internet  192.168.96.18           0     50bd.9dc4.7af2  ARPA   Vlan11

the user got an ip conflict message. Eventually, user ended up with 192.168.96.18 IP.
is the layer 3 switch doing something that causes this.
Appreciate if someone can put some light on this to investigate further. the SVI vlan configuration
is also given. Thanks in advance.
(mac 50bd.9dc4.7af2 belongs to the user)

interface Vlan6
 ip address 192.168.96.0 255.255.240.0
 ip helper-address 10.56.0.12
 no ip redirects
 no ip unreachables
 ip directed-broadcast 101
 no ip proxy-arp
 ip verify unicast source reachable-via rx
 ip pim dr-priority 100
 ip pim sparse-mode

2 Replies 2

STEPAN JANKOVIC
Level 1
Level 1

Hello,

from arp table we can see that you effectively use address space 192.168.96.x/unknown mask in vlan 11. from vlan 6 SVI we can see that you are using the same address space on Vlan6. This is not correct and causes conflict. It may be misconfiguration of VLAN11 SVI or misconfiguration of DHCP server.

Regards

Stepan

apologies, that is a typo.
Vlan 11 is correct . Appreciate inputs.

sh ip arp | i 7af2
Internet  192.168.96.145         42   50bd.9dc4.7af2  ARPA   Vlan11
Internet  192.168.96.52          43   50bd.9dc4.7af2  ARPA   Vlan11
Internet  192.168.96.18           0     50bd.9dc4.7af2  ARPA   Vlan11


interface Vlan11
 ip address 192.168.96.0 255.255.240.0
 ip helper-address 10.56.0.12
 no ip redirects
 no ip unreachables
 ip directed-broadcast 101
 no ip proxy-arp
 ip verify unicast source reachable-via rx
 ip pim dr-priority 100
 ip pim sparse-mode

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