Performing traceroutes on both endpoints to the other is a great way to detect this. As this issue has just started, it does make sense to look at any potential changes.Ī second reason this may occur is if your network topology has changed and you end up with something called asymmetric routing, whereby the traffic is sent via one gateway, but received by another, as the gateways don’t see traffic flowing in both directions they can determine the traffic is invalid and close the session. Realistically most firewalls won’t do this for TCP traffic as it is stateful, whereas for UDP it’s common to see a 30-300 second timer due to them having no stateful control. The firewalls I tend to work with have keep-alives of 3-8 hours. So if the firewall doesn’t see any traffic for 30 seconds, it will consider the connection dead and close the connection. This can cause issues because you might have a TCP keep-alive timer within your application of 300 seconds for example, but the firewall has a keep-alive timer of only 30 seconds. These gateway devices have a finite amount of network ports available but can carry huge amounts of traffic, so it is more important for these devices to ensure stale connections are closed as soon as possible, if they don’t, they may not have capacity for new traffic. When you have any device performing NAT or a firewall in the middle, this gets more interesting. TCP keepalive probe is a way of handling this, if the proxy is busy gathering data and hasn’t sent a packet to the repository’s data mover for a while, it can send a keep alive (this is nothing magic, just part of the TCP specification) to keep the connection alive. To ensure that if a connection has failed or otherwise not been terminated properly, the endpoints need to know when to consider a connection dropped. Hi does indeed, TCP is a stateful connection between two endpoints. (My thought process here is that you could have two sites, a proxy at each and then the job set to automatically select proxies, then you could be trying to reach your source environment from across a site-to-site VPN or MPLS).
![unable to transmit transmit failure unable to transmit transmit failure](https://support.keriocontrol.gfi.com/hc/article_attachments/360014220680/smtp_scanning_disable.png)
Can you provide information on where your proxy and repository roles are and whether the backup job has any specified proxies or just set to use automatic.Based on your mention of firewalls, is this a site-to-site or to cloud backup or to local storage? In summary, is there an MPLS/WAN involved?.
![unable to transmit transmit failure unable to transmit transmit failure](https://i.stack.imgur.com/Kc9Tj.png)
More information here greatly appreciated).
UNABLE TO TRANSMIT TRANSMIT FAILURE WINDOWS
(You haven’t given much information here so I’m assuming Windows proxy hosts, domain joined, windows firewall enabled. Depending on the answer to question 2, I’ve seen issues whereby servers have come online but haven’t recognised they’re on a domain network and their Windows firewall profile changes.What’s the uptime on your servers? Has anything been patched recently?.Have you changed anything in your network topology?.
UNABLE TO TRANSMIT TRANSMIT FAILURE HOW TO
As per your “I need to figure out how to resolve this issue immediately.”, this is a community forum so you’re best engaging with Veeam Support directly for your issue.