Difference between revisions of "Troubleshooting"

Revision as of 12:24, 8 November 2018

Check the switch port based on IP address

• On core switch
  • show arp | include 192.168.200.100
  • show mac address-table | include 3a00.031e.bb00
• Locate the access switch from above input
• On access switch
  • show mac address-table | include 3a00.031e.bb00

Check IP based on MAC address

• show arp | include 0000.0000.0001

Arp entry does not age out and need clean arp cache manually

• Command clean arp-cache may not work
• And need to use command clean ip arp
• Cisco Bug cscsk46195
• In Cisco IOS® software, the ARP cache timeout is set to four hours (240 minutes) by default
  • Show interface vlan 10 | include ARP
• The extra time is the jitter added to each dynamic ARP entry when it is created. Random jitter is added to the ARP cache timeout in order to avoid synchronous expiration of the ARP entries, which might trigger an ARP storm. Jitter should be a random number between 0 seconds and 30 minutes, with a maximum jitter of 30 minutes
  • show arp 192.168.200.100 detail

Debug DHCP

• debug dhcp server events
• show ip dhcp pool VLAN10
• show ip dhcp conflict
• no ip dhcp conflict logging
• ip dhcp conflict resolution

10/100/1000M port only work on 100M mode

• Cat 5E or higher
• All 4 pairs

Lost package when ping iDRAC IP address

• iDRAC may not work properly on 10/100/1000M Auto mode
• Set 100M on switch port manually

MAC Vendor Lookup

• https://macvendors.com/