Slower transfer speeds between VLANs vs same VLAN

I am using Sangfor firewall as a gateway (router) with various VLANs, but I'm experiencing notably slow data transfer speeds in the Kbps range when copying data from one VLAN to another. I seek assistance in addressing this issue.

Here are some Troubleshooting steps
Did you check it on Single PC on both end ? (connect the PCs directly on NGAF ports)
also check on different ports of NGAF

Kindly check your ethernet connectivity, or network switches

Also check after disable the bandwidth policy (If its enable)

HiHi,

Are you trying to ping VLANs to each other?  Is it unable to ping a PC on a different VLAN?

If yes, please follow the link below to create a LAN-to-LAN allow policy:

https://knowledgebase.sangfor.com/detailPage?articleData=%7B%22articleType%22%3A1,%22articleId%22%3A%2282aef540c86b41b58d3017013000472f%22,%22keyword%22%3A%22%22%7D

slower data transfer speed between VLANs could be attributed to several factors. below are some  that you need to check to address the issue:

1. check firewall rules and policies and verify if rules are correctly configured to allow inter VLAN traffic
2. check the physical network infrastructure including cables, switches, and network interfaces to ensure no physical issues are causing the slow transfer
3. assess network bandwidth to determine if congestion is happening since it can affects the intern VLAN traffic. you may also monitor the traffic during transfer using tools like SNMP or other network monitoring tools
4. confirm if inter-VLAN routing is allowed on your Sangfor firewall. You may also check any misconfigurations in routing tables or gateway
5. if all else fails, you may consult Sangfor support for immediate assistance and resolution

Slower transfer speeds between VLANs compared to transfers within the same VLAN can be attributed to several factors within the network infrastructure. Ensure that the Sangfor firewall's routing capabilities are optimized for inter-VLAN traffic by confirming that its configuration allows efficient routing and isn’t bottlenecked by excessive rules or limitations. Additionally, inspect the network switches to guarantee they support sufficient throughput for inter-VLAN traffic and have proper VLAN configurations without any misconfigurations or bottlenecks at the port level. Investigate potential congestion points, ensuring there are no bandwidth constraints, and consider segregating heavy traffic devices or applications onto different VLANs to alleviate network congestion. Conducting thorough tests, examining the firewall settings, checking switch configurations, and potentially redistributing network loads can help resolve the slow transfer speeds between VLANs.

If these VLANs are part of your LAN segment then check Policies > Access Control in the application control policy. If there is only allows connection from LAN to WAN, then create a separate allow policy from LAN to LAN.

Hi, you have to check your networking devices in order to troubleshooting this issues about intra vlan traffic. I suggest you that if you have two vlans that do a lot of traffic to each other, you can use a layer 3 switch in order to set it as a gateway on these two vlans to avoid uneccessary traffic data to go to sangfor firewall. Layer 3 Switch are made to manage a lot of traffic between vlans.

Hi,
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VPN are configured correctly, then they function very well in unison that offer amalgamated strengths, and functions.
Thanks

there are several possible causes and troubleshooting steps you can try:

1. Basic troubleshooting:

    Verify cable connections: Ensure all network cables are securely plugged into the correct ports on the Sangfor firewall and other network devices. Faulty or loose cables can significantly impact data transfer speeds.
    Reboot devices: Sometimes, a simple reboot of the Sangfor firewall and other network devices can resolve temporary glitches or software issues.
    Check for errors: Look for any error messages in the Sangfor firewall logs or event viewer on other devices. These may provide clues about the source of the slow speeds.

2. Sangfor firewall configuration:

    Inter-VLAN routing: Make sure inter-VLAN routing is enabled on the Sangfor firewall for the specific VLANs experiencing slow speeds. You may need to consult the Sangfor documentation for specific configuration steps.
    QoS settings: Check if any Quality of Service (QoS) settings are applied on the Sangfor firewall that might be prioritizing other traffic over data transfers between VLANs. Adjust QoS settings if necessary to prioritize data transfers.
    Security policies: Review any security policies applied to the VLANs that might be throttling data transfer speeds. For example, if you have intrusion detection or prevention systems enabled, they might be impacting performance.

3. Network equipment:

    Check for overloaded interfaces: If the interfaces on the Sangfor firewall or other network devices are overloaded with traffic, it can lead to slowdowns. Use monitoring tools to check interface utilization and identify any bottlenecks.
    Faulty hardware: Although less likely, it's possible that faulty hardware on the Sangfor firewall or other network devices could be causing the slow speeds. If you've exhausted other troubleshooting options, consider replacing any suspected hardware.

4. Additional tips:

    Upgrade firmware: Ensure you're using the latest firmware version for the Sangfor firewall and other network devices. Outdated firmware can sometimes cause performance issues.
    Contact Sangfor support: If you've tried all of the above troubleshooting steps and are still experiencing slow speeds, contact Sangfor support for further assistance. They may be able to provide more specific guidance based on your network configuration and logs.

can try check iperf from vlan to another vlan and check, also factors on protocol or port permission on the firewall need to be carefully not deny certain port that can affect transfer of data