Ip Conflict Resolver

November 20, 2008 @ 4:09 pm · Filed under CCIE Study

I think Dynamic ARP Inspection is what you need ….
Catalyst 3560 Switch Software Configuration Guide, Rel. 12.2(46)SE Configuring Dynamic ARP Inspection Dynamic ARP inspection is a security feature that validates ARP packets in a network. It intercepts, logs, and discards ARP packets with invalid IP-to-MAC address bindings. This capability protects the network from certain man-in-the-middle attacks. Dynamic ARP inspection ensures that only valid ARP requests and responses are relayed. The switch performs these activities: Intercepts all ARP requests and responses on untrusted ports Verifies that each of these intercepted packets has a valid IP-to-MAC address binding before updating the local ARP cache or before forwarding the packet to the appropriate destination Drops invalid ARP packets Dynamic ARP inspection determines the validity of an ARP packet based on valid IP-to-MAC address bindings stored in a trusted database, the DHCP snooping binding database. This database is built by DHCP snooping if DHCP snooping is enabled on the VLANs and on the switch. If the ARP packet is received on a trusted interface, the switch forwards the packet without any checks. On untrusted interfaces, the switch forwards the packet only if it is valid. You enable dynamic ARP inspection on a per-VLAN basis by using the ip arp inspection vlan vlan-range global configuration command. For configuration information, see the “Configuring Dynamic ARP Inspection in DHCP Environments” section. In non-DHCP environments, dynamic ARP inspection can validate ARP packets against user-configured ARP access control lists (ACLs) for hosts with statically configured IP addresses. You define an ARP ACL by using the arp access-list acl-name global configuration command. For configuration information, see the “Configuring ARP ACLs for Non-DHCP Environments” section. The switch logs dropped packets. For more information about the log buffer, see the “Logging of Dropped Packets” section. e.g.
Switch(config)# arp access-list host2 Switch(config-arp-acl)# permit ip host 1.1.1.1 mac host 1.1.1 Switch(config-arp-acl)# exit Switch(config)# ip arp inspection filter host2 vlan 1 Switch(config)# interface gigabitethernet0/1 Switch(config-if)# no ip arp inspection trust
— On Thu, 11/20/08, Mark Stephanus Chandra wrote:
From: Mark Stephanus Chandra Subject: Ip Conflict Resolver To: ccielab@groupstudy.com Date: Thursday, November 20, 2008, 9:22 PM
Guys,

It’s kinda out of topic from ccie lab,

but I just wondering after googling several times, I still cannot find the solution.

So the problem is , In My company, we use static ip to connect to LAN. But the problem is, a lot of ip conflict in the network and unfortunately, sometimes there are users using my President Director IP Address.

So, that make world war 3 in my office