Dell EMC Unity: How to troubleshoot network connectivity issue such as ping failure (Customer Correctable)

Summary: 1. Unity IP not pingable. 2. ping only works in one direction but fails in the other. 3. ping only works in the same subnet.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
Check out other resources

Instructions

When end users report network connectivity problem, run some tests to narrow down the root cause according to different scenarios.
  1. ping the Unity IP from a host which lost access.
  2. ping the Unity IP from the gateway.
  3. ping the gateway or host from Unity IP by  /net/util/ping -srcIf <value> -addr <value> . Example:
uemcli /net/util ping -srcIf if_8 -addr 172.23.24.254
 
Note: To list the value of srclf, check the output of  uemcli /net/if show .


Scenario 1: The Unity IP cannot communicate with the gateway or host in both directions.

1. Check the physical port state. Example:

root@(none) spa:~> uemcli /net/port -id spa_iom_0_eth0 show -detail
1:    ID                 = spa_iom_0_eth0
      Role               = frontend
      SP                 = spa
      Supported types    = file, net, iscsi
      MTU size           = 9000
      Speed              =
      Health state       = Minor failure (15)
      Health details     = "The port has lost communication with the network. 
      Operational status = OK (0x2), Link Down (0x8011)
 
This result generally means cabling issue. Need to check the physical connection onsite.

Note: Run "uemcli /net/if show" to get the port ID of the problematic IP address.
 
2. For bond port (Link Aggregation), check the health state in bond level as well. Example:

service@(none) spb:~> uemcli /net/la show
1:    ID                 = spa_la_0_1
      SP                 =
      Ports              = spa_iom_0_eth1, spa_iom_0_eth0
      MTU size           = 9000
      Health state       = Minor failure (15)
 
Link Aggregation problems are usually caused by the wrong configuration on switch ports. Make sure all the ports have been added to the same channel-group with active mode. Example:

(config-if)# int fa 0/1
(config-if)# channel-group 1 mode active
(config-if)# int fa 0/2
(config-if)# channel-group 1 mode active
 
3. A wrong vlan setting can also cause this problem. View and update the vlanId by  uemcli /net/if . Example:

root@spa:/cores/service>uemcli /net/if -id if_40 show |egrep "ID|VLAN"
1:ID= if_40
VLAN ID= 12
 
root@spa:/cores/service>uemcli -u admin -p P@ssw0rd /net/if -id if_40 set -vlanId 123
 
Note: To unset vlan tag, use empty quotes since it does not accept zero. Example:
root@spa:/cores/service>uemcli -u admin -p P@ssw0rd /net/if -id if_40 set -vlanId ""
 
Scenario 2: Unity IP can only communicate with gateway and hosts in some subnets, but not others.

This is usually caused by the wrong routing table. Run  ip rule list  and  ip route list  to view the settings. Example:

root@spa:/cores/service>ip rule list
0:      from all lookup local
32735:  from 138.138.138.138 lookup 47
32736:  from all fwmark 0x800e lookup 45
32738:  from 10.32.106.115 lookup 42
 
root@spa:/cores/service>ip route list table 42
default via 10.32.106.1 dev mgmt_vdev  proto static  src 10.32.106.115
10.32.106.0/24 dev mgmt_vdev  proto static  src 10.32.106.115

If any problem is found, update routing table via Unisphere GUI or uemcli.  ip route add  can temporarily work, but the update will be cleared in next reboot. Following is one example:

root@spb:/cores/service>ip route add default via 172.23.24.254 src 172.23.24.34 table 12

Scenario 3: The host and gateway can ping Unity IP, but Unity IP cannot ping them. It usually means IP Reflect is enabled but vlan ID or routing table is wrong. Example:
 
service@(none) spb:~> uemcli /net/nas/server -id nas_101 show -detail |grep Reflect
Packet Reflect enabled                      = yes

IP Reflect saves the Source & Destination MAC Addresses and VLAN ID of incoming packets, and then send back packets from the same NIC with the saved information. With such mechanism, the routing table and vlan setting is not used when replying packets. That s why the gateway and host can ping Unity IP even when the vlan setting or routing table is wrong.

When the ping is from Unity IP to the gateway or host, the wrong routing table or vlan setting is used, so the ping fails.

Note: To check the vlan, refer to Scenario 1, point 4. To check the routing table, refer to Scenario 2.

If all the settings on Unity and switch port look fine, but the connectivity problem is still there, capture a network trace during ping and engage GNS for help. Example:
 
root@spa:/cores/service>tcpdump -i eth3 -s 0 -w /home/service/connect_problem.cap

Affected Products

Dell EMC Unity Family

Products

Dell EMC Unity Family
Article Properties
Article Number: 000018959
Article Type: How To
Last Modified: 08 Oct 2024
Version:  3
Find answers to your questions from other Dell users
Support Services
Check if your device is covered by Support Services.