High ARP cache usage for Cisco Nexus

Vendor

Cisco

Description

Indeni will alert when the number of ARP entries stored by a device is nearing the allowed limit.

Remediation Steps

Identify the cause of the large ARP table. If it is due to a legitimate cause, such as a high number of hosts visible on the available networks, please contact your technical support provider.

1. Use the "show iparp" NX-OS command to display the Address Resolution Protocol (ARP) table statistics. Note: You must use the feature interface-vlan command before you can display the ARP information for VLAN interfaces.

2. Review the ARP table for unknown hosts which may saturate the ARP table of the switch.

3. If the number of ARP entries is normal then consider to upgrade the Nexus switch since it is close to the ARP limit capacity.

4. For more information review the next Cisco Configuration guide: https://www.cisco.com/c/m/en_us/techdoc/dc/reference/cli/n5k/commands/show-ip-arp.html

How does this work?

This script logs into the Cisco Nexus switch using SSH and retrieves the output of the "show inventory" command. The reported device type is used to identify the ARP cache size value based on a static table. Nexus 3000: 4,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3000/sw/scalability/7x/b_Nexus3k_Verified_Scalability_7x/b_Nexus3k_Verified_Scalability_7x_chapter_01.html) Nexus 5000: 8,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration_limits/limits_513/nexus_5000_config_limits_513.html) Nexus 5500: 8,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5500/sw/Verified_Scalability/700N11/b_N5500_Verified_Scalability_700N11/b_N5500_Verified_Scalability_700N11_chapter_01.html Nexus 5600: 32,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/verified_scalability/701N11/b_N5600_Verified_Scalability_701N11/b_N6000_Verified_Scalability_700N11_chapter_01.html) Nexus 6000: 32,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/verified_scalability/701N11/b_N5600_Verified_Scalability_701N11/b_N6000_Verified_Scalability_700N11_chapter_01.html) Nexus 7000: 60,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/6_x/nx-os/unicast/configuration/guide/b-7k-Cisco-Nexus-7000-Series-NX-OS-Unicast-Routing-Configuration-Guide-Release-6x/n7k_unicast_managinging_rib_fib.html) Nexus 9300: 5,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/scalability/guide_703I11/b_Cisco_Nexus_9000_Series_NX-OS_Verified_Scalability_Guide_703I11.html) Nexus 9500: 40,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/scalability/guide_703I11/b_Cisco_Nexus_9000_Series_NX-OS_Verified_Scalability_Guide_703I11.html)

Why is this important?

This script logs into the Cisco Nexus switch using SSH and retrieves the output of the "show inventory" command. The reported device type is used to identify the ARP cache size value based on a static table. Nexus 3000: 4,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3000/sw/scalability/7x/b_Nexus3k_Verified_Scalability_7x/b_Nexus3k_Verified_Scalability_7x_chapter_01.html) Nexus 5000: 8,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration_limits/limits_513/nexus_5000_config_limits_513.html) Nexus 5500: 8,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5500/sw/Verified_Scalability/700N11/b_N5500_Verified_Scalability_700N11/b_N5500_Verified_Scalability_700N11_chapter_01.html Nexus 5600: 32,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/verified_scalability/701N11/b_N5600_Verified_Scalability_701N11/b_N6000_Verified_Scalability_700N11_chapter_01.html) Nexus 6000: 32,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/verified_scalability/701N11/b_N5600_Verified_Scalability_701N11/b_N6000_Verified_Scalability_700N11_chapter_01.html) Nexus 7000: 60,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/6_x/nx-os/unicast/configuration/guide/b-7k-Cisco-Nexus-7000-Series-NX-OS-Unicast-Routing-Configuration-Guide-Release-6x/n7k_unicast_managinging_rib_fib.html) Nexus 9300: 5,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/scalability/guide_703I11/b_Cisco_Nexus_9000_Series_NX-OS_Verified_Scalability_Guide_703I11.html) Nexus 9500: 40,000 (http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/scalability/guide_703I11/b_Cisco_Nexus_9000_Series_NX-OS_Verified_Scalability_Guide_703I11.html)

Without Indeni how would you find this?

This data is not available through SNMP or syslog.


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