Search the VMware Knowledge Base (KB)
View by Article ID

Rescanning takes a long time when using multiple VMkernel ports with port binding to access two or more storage arrays on different broadcast domains (2017084)

  • 13 Ratings


When using multiple VMkernel ports with port binding to access two or more storage arrays on different broadcast domains, you experience these symptoms:
  • Rescan times take longer than usual.
  • Incorrect number of paths are seen per device.
  • In the syslog.log (ESXi 5.x) or vmkiscsid.log (ESX 4.x) file, you see entries similar to:

    T15:51:19Z iscsid: Login Target: if=iscsi_vmk@vmk5 addr= (TPGT:1 ISID:0x2)
    2012-03-05T15:51:19Z iscsid: Notice: Assigned (H34 T4 C1 session=c6, target=5/5)
    2012-03-05T15:51:19Z iscsid: Notice: Setting NODELACK for (host=
    2012-03-05T15:51:19Z iscsid: cannot make a connection to (101,Network is unreachable)
    2012-03-05T15:51:19Z iscsid: Notice: Reclaimed Channel (H34 T4 C1 oid=5)
    2012-03-05T15:51:19Z iscsid: session login failed with error 4,retryCount=0
    2012-03-05T15:51:19Z iscsid: Login Target Failed:
    if=iscsi_vmk@vmk5 addr= (TPGT:1 ISID:0x2) err=4
    2012-03-05T15:51:19Z iscsid: Login Failed:
    if=iscsi_vmk@vmk5 addr= (TPGT:1 ISID:0x2) Reason: 00040000 (Initiator Connection Failure)

    Note: For more information on log locations, see:


This issue occurs if you have different broadcast domains in conjunction with port binding, which is used to enable multipathing with a single target portgroup array.

Consider this sample iSCSI configuration, assuming the standard class-C netmask (

ESXi/ESX host:
  • vmk1 IP –
  • vmk2 IP –
  • vmk3 IP –
  • vmk4 IP –
Storage arrays:
  • SAN A IP –
  • SAN B IP –
When port binding is used, the software iSCSI stack asks all VMkernel ports to log in to all available targets on the storage arrays. This results in vmkernel ports vmk1 ( and vmk3 ( attempting to establish communication with the SAN B IP address (, and vice versa.

Port binding requires that all target ports of the storage array must reside on the same broadcast domain as the vmkernel ports because routing is not supported with port binding.


To work around this issue, use one of these options:

  • Ensure you have both arrays on the same broadcast domain, resulting in all vmkernel ports being able to access all target port groups.
  • Split the SANs into Software/Hardware Independent iSCSI, Software Hardware Dependent iSCSI, or two Hardware iSCSI domains.
Note: For some storage vendors that utilize ICMP pings to determine the link status between the array and the ESXi/ESX host, try disabling the ping requests to the unreachable vmkernel ports.

See Also

Update History

10/18/2013 - Added ESXi 5.5 to Product Versions.

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


  • 13 Ratings

Did this article help you?
This article resolved my issue.
This article did not resolve my issue.
This article helped but additional information was required to resolve my issue.

What can we do to improve this information? (4000 or fewer characters)

Please enter the Captcha code before clicking Submit.
  • 13 Ratings