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We are seeing the package lost while Sent Traffic through expressRoute Circuits and in the network capture we see fragmentation packets.
Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
I understand that you are facing packet loss and fragmentation issues with ExpressRoute connection.
To troubleshoot issues related with Azure ExpressRoute, we will need a specialized 1:1 session, where a support engineer can have a screen share session to pinpoint the issue. If you have a support plan you may file a support ticket.
In case you require one-time free support, please send an email with subject line “Attn:kaananth | How to fix the fragmentation issue. Traffic is getting dropped due to fragmentation” to AzCommunity[at]Microsoft[dot]com
with the following details, I will follow-up with you.
• Reference this Q&A thread URL
• Azure Subscription ID
• Azure resource ID
Note: Please do not share any PII data as a public comment.
Cheers,
Kapil
Hi, The recommended MTU is 1350 bytes. If it's greater the fragmentation happens at the ER gateway. You can try to enable ER fastpath and check if that helps.