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Issues with sending email on a 1820 24G switch with VLAN enabled

 
Madcow_Ollie
Occasional Contributor

Issues with sending email on a 1820 24G switch with VLAN enabled

Issues with sending email on a 1820 24G switch with VLAN enabled

Hello

My office has just upgraded to the 1820 24G series switches. I have setup 5 different VLAN's. I have my servers and workstations on one and several other servers on an isolated VLAN as well as a voice VLAN.

We have Office365 and is configured with Outlook 2016. Internet works fine, no issues with video, audio or any type of TCP/UDP connection. However there is one strange issue i cannot seem to get a hold of. When on a VLAN my Outlook tends to have issues sending email and can sit in the inbox for quite some time. I have noticed when sending plain text emails it seems to work ok but when i attach my signature or other images, basically a larger email in size., my Outlook outbox begins to build up. I am not a complete noob and i do have at least the bare basic knowledge if not even intermediate. So I cannot figure out as to why this type of packet is being lost. I know the Office 365 SMTP server is smtp.office365.com and uses port 443 to send out email or make the connection. I have ran some wireshark packet capturing and i will post my findings below.

 

25098 254.333223 192.168.93.32 132.245.42.242 TCP 54 50645 → 443 [ACK] Seq=1 Ack=7357 Win=256 Len=0

28707 299.333584 132.245.42.242 192.168.93.32 TLSv1.2 139 Application Data

28709 299.333929 192.168.93.32 132.245.42.242 TCP 54 50645 → 443 [ACK] Seq=1 Ack=8583 Win=256 Len=0

29941 312.509098 192.168.93.32 132.245.42.242 TCP 66 51367 → 443 [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1

29951 312.615293 132.245.42.242 192.168.93.32 TCP 66 443 → 51369 [SYN, ACK] Seq=0 Ack=1 Win=8190 Len=0 MSS=1460 WS=16 SACK_PERM=1

30019 312.893771 132.245.42.242 192.168.93.32 TLSv1.2 161 Change Cipher Spec, Encrypted Handshake Message

30020 312.894658 192.168.93.32 132.245.42.242 TLSv1.2 523 Application Data

30021 312.894889 192.168.93.32 132.245.42.242 TCP 4434 [TCP segment of a reassembled PDU]

30036 312.998039 132.245.42.242 192.168.93.32 TCP 60 443 → 51369 [ACK] Seq=5874 Ack=882 Win=64768 Len=0

30037 312.998089 192.168.93.32 132.245.42.242 TCP 1514 [TCP segment of a reassembled PDU]

30072 313.298977 192.168.93.32 132.245.42.242 TCP 1514 [TCP Retransmission] 51369 → 443 [ACK] Seq=882 Ack=5874 Win=65536 Len=1460

30080 313.361295 192.168.93.32 132.245.42.242 TCP 1514 [TCP Retransmission] 51367 → 443 [ACK] Seq=882 Ack=5874 Win=65536 Len=1460

30087 313.442353 192.168.93.32 132.245.42.242 TCP 1514 [TCP Retransmission] 51368 → 443 [ACK] Seq=882 Ack=5874 Win=65536 Len=1460

Thanks

2 REPLIES
Madcow_Ollie
Occasional Contributor

Re: Issues with sending email on a 1820 24G switch with VLAN enabled

Hey all

here is a post of my wireshark findings below.

 

Dunky
Regular Advisor

Re: Issues with sending email on a 1820 24G switch with VLAN enabled

Hi. Not sure why you would think this has anything to do with the switch?

Have you seen this article> https://support.microsoft.com/en-us/kb/2441551

 

Edit: Do you have some AV that is causing the problem with attachments?