SUMMARY: Hostflapping Issue

From: Peebles, Robert <>
Date: Thu Jul 24 2008 - 14:53:55 EDT
Thanks to Francisco for letting me know about this issue:

However, this was not our problem.  The ST2540 has an unresolved bug.
Here's the description that the Sun support engineer sent us:

  ST2540 could send packets coming from a host back to the SWITCH,
  (forwards the same packets on the network again.)
  So the SWITCH stores the host's MAC address info on the Port
  connected to the ST2540.

  SWITCH PortA <------ Host
  PortB ------> ST2540
  <====== !! (fowards the same packet back to the PortB)

  The SWITCH misunderstands the Host is being connected to the PortB
  because the "forwarded" packet has the Host's MAC address as the
  "source MAC".  So if SWITCH receives packets to the Host,
  then forwards the packets to PortB, not PortA.

There are 2 workarounds:

1) Connect the NICs on the switch to a hub and connect a NIC on the
server to a hub; OR
2) Make direct network connections between the switch and the server
using crossover cables.



-----Original Message-----
[] On Behalf Of Peebles,
Sent: Wednesday, July 23, 2008 9:26 AM
To: sunmanagers
Subject: Hostflapping Issue


I have a Sun X4600 running Solaris 10 8/07 connected to an ST2540 array
via FC HBAs.

Both the server and the array are on the same subnet connected to the
same Cisco 4507 switch.

Numerous times every day the server's IP address stops responding to
pings.  When this occurs, the MAC address of the Sun's NIC appears on
the switch port that is connected to the NIC on the ST2540.

I can't comprehend how the MAC address on the Sun can show up on a port
connected to the array, unless it's a switch issue.

Has anyone else experienced this problem?  I would greatly appreciate
any light that could be shed on this issue.


sunmanagers mailing list
sunmanagers mailing list
Received on Thu Jul 24 14:55:49 2008

This archive was generated by hypermail 2.1.8 : Thu Mar 03 2016 - 06:44:11 EST