Troubleshooting an issue with SMTP mail delivery for autosupport on an IBM N6240 (FAS 3050 I believe).
Mail conversation starts up but then never succeeds fully. Mail server just shows a reset or that the NetApp dropped connection.
Ran pktt during the SMTP conversation on the NetApp side and saw that we were receiving ICMP Fragmentation Needed messages (requesting MTU 1400) from an upstream router. However, the NetApp continued to send its data at full frame size (1500 bytes - overhead or 1448 bytes). These don't get through and the SMTP conversation stalls.
Confirmed that delivery via a local SMTP server which doesn't require fragmentation works fine.
This is ONTAP 8.0.2P3.
Anyone have any idea why the network stack isn't honoring the fragmentation requests?
Thanks, Ray
On Tue, Sep 25, 2012 at 07:30:16PM -0700, Ray Van Dolson wrote:
Troubleshooting an issue with SMTP mail delivery for autosupport on an IBM N6240 (FAS 3050 I believe).
Mail conversation starts up but then never succeeds fully. Mail server just shows a reset or that the NetApp dropped connection.
Ran pktt during the SMTP conversation on the NetApp side and saw that we were receiving ICMP Fragmentation Needed messages (requesting MTU 1400) from an upstream router. However, the NetApp continued to send its data at full frame size (1500 bytes - overhead or 1448 bytes). These don't get through and the SMTP conversation stalls.
Confirmed that delivery via a local SMTP server which doesn't require fragmentation works fine.
This is ONTAP 8.0.2P3.
Anyone have any idea why the network stack isn't honoring the fragmentation requests?
Thanks, Ray
This[1] appears to be my issue. Will pursue one of the workarounds or look to upgrade ONTAP.
Thanks, Ray
[1] http://support.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=540316
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Ray Van Dolson