How to check ARP and MAC address entries on S series switches

0

For S series switches (except the S1700), you can run the display mac-address command to check MAC address entries and run the display arp command to check ARP entries.

Other related questions:
How do I delete MAC address and ARP entries on S series switch
For S series switches (except S1700 switches), you can delete MAC address entries and ARP entries as follows: 1. Clear MAC address entries. In the system view, run the undo mac-address dynamic command to delete all dynamic MAC address entries. In the system view, run the undo mac-address static command to delete all static MAC address entries. 2. Clear ARP entries. In the user view, run the reset arp dynamic command to delete all dynamic ARP entries. In the system view, run the undo arp static ip-address command to delete all static ARP entries.

How to delete MAC address entries from S series switches
You can run the following commands to delete MAC address entries from an S (except the S1700) or E series switch: 1. Run the undo mac-address command in the system view to delete all MAC address entries. 2. Run the undo mac-address vlan vlan-id command in the system view to delete MAC address entries in a specified VLAN. 3. Run the undo mac-address interface-type interface-number command in the system view to delete MAC address entries on a specified interface.

How does an S series switch process ARP and MAC address entries when the STP topology changes
When the STP topology changes, an S series switch (except the S1700) processes ARP and MAC address entries as follows: 1. By default, all ports enter the Discarding state after STP is enabled. When the STP topology changes, dynamic ARP entries and MAC addresses on all ports are deleted. 2. When a port enters the Discarding state during normal running of the system, dynamic ARP and MAC address entries on the port are deleted. In addition, the device sends a TC packet to the upstream device, requesting it to delete the dynamic ARP and MAC address entries. When the root node receives the TC packet, the topology of the entire network converges.

View ARP entries on S series switches
If an S series switch (except the S1700 switch�? works at Layer 2, you can only view the MAC addresses of devices connected to an interface, not the IP addresses. You can run the display mac-address command. The command output is as follows: MAC address table of slot 0: MAC Address VLAN/ PEVLAN CEVLAN Port Type LSP/LSR-ID VSI/SI MAC-Tunnel 5489-980d-4ef6 1 - - GE0/0/1 dynamic 0/- 5489-98c2-19e3 20 - - GE0/0/2 dynamic 0/- Total matching items on slot 0 displayed = 2 ——————————————————————————————————————�?If an S series switch (except the S1700 switch�? works at Layer 3, you can run the display arp [ all ] command to view ARP entries including mappings between IP addresses and MAC addresses. In addition, you can find the outbound interfaces toward the devices based on the mappings. The command output is as follows: IP ADDRESS MAC ADDRESS EXPIRE(M) TYPE INTERFACE VPN-INSTANCE VLAN/CEVLAN 10.137.217.202 00e0-0987-7890 I - Eth0/0/0 10.137.216.1 0000-5e00-0149 20 D-0 Eth0/0/0 Total:2 Dynamic:1 Static:0 Interface:1 ———————————————————————————————————————�?With known MAC addresses or IP addresses, you can obtain outbound interfaces and mappings between IP addresses and MAC addresses of specific devices based on the MAC table or ARP table on the switch. In the preceding output, if the MAC ADDRESS field is Incomplete, the ARP entry is temporary. When an IP packet triggers an ARP Miss message, the switch generates a temporary ARP entry and sends ARP Request packets to the destination network segment. The following situations may occur before the temporary ARP entry ages: Before receiving an ARP Reply packet, the switch discards IP packets matching the temporary ARP. No ARP Miss message will be triggered. After receiving the ARP Reply packet, the switch generates a correct ARP entry to replace the temporary ARP entry. When the temporary ARP entry expires, the switch deletes it.

Configure ARP entry update upon MAC address change on S series switch
principals of ARP entry update upon MAC address change on S series switches (except S1700): Every device on a network has an IP address, which is used to communicate with other devices. On an Ethernet, hosts, switches, or routers send and receive Ethernet data frames based on MAC addresses. ARP provides mappings between IP addresses and MAC addresses. When devices on different network segments communicate, ARP entries must be used to map IP addresses to correct MAC addresses and outbound interfaces. If you change the location of a host to connect the host to another interface of a switch, the host's MAC address will be learned on this interface and the outbound interface corresponding to the MAC address will change. However, the outbound interface in the ARP entry will be updated only after the aging time expires. Before the aging time expires, the switch will use the incorrect ARP entry for communication. After the mac-address update arp command is configured in the system view, the outbound interface in an ARP entry can be updated based on the outbound interface in an MAC address entry. Precautions: 1. This command is valid only for dynamic ARP entries instead of static ARP entries. 2. The mac-address update arp command will not take effect after the arp anti-attack entry-check enable command is executed to configure fixed ARP. 3. After ARP entry update upon MAC address change is enabled, an ARP entry is updated only when the outbound interface in the corresponding MAC address entry changes. 4. Configuring ARP entry update upon MAC address change will cause the gratuitous ARP packet discarding function to become ineffective. 5. S series switches running versions earlier than V100R006C00 do not support ARP entry update upon MAC address change.

If you have more questions, you can seek help from following ways:
To iKnow To Live Chat
Scroll to top