Query:
Why do I have issues opening large file even if ping works properly?
Answer:
This section provides solution for common causes of performance issues with SDWAN.
Fragmentation on the WAN
In SDWAN, the additional overhead of the tunnel encapsulation overhead reduces the effective MTU of the site to site paths. This causes fragmentation. In pre-fragmentation process, the original packet is fragmented, if too big, before it is encapsulated and is re-assembled on the remote site. Fragmentation and reassembling causes performance problems.
Solution
Follow these steps to overcome performance problems caused due to traffic fragmentation:
- Set system session tcp-adjust-mss enable true interface-types all to enable tcp mss adjustment on all site, for SDWAN traffic.
- Set tcp mss adjustment to a specific value, if TCP traffic is getting fragmented even after enabling tcp mss adjustment on all sites.
There are possibilities of lower MTU interface in the network path.By default, the MSS adjustment is set automatically based on the MTU of the ingress and egress interface of the traffic transiting the Versa appliance.
- Check the output of show vsm stats datapath and show vsf tunnel stats, at the vsmd debug shell, on both local and remote sites to check if fragmentation counters are going up.
Traffic Taking a Suboptimal Path
There are chances of traffic going over a high latency circuit or loss circuit.
Solution
Follow these steps to overcome problems caused due to traffic taking a suboptimal path:
- Run show orgs org <org-name> sd-wan sla-monitor status <remote-branch-name> command to look at the path SLA metrics.
- If traffic is taking a suboptimal path, use SDWAN policies, forwarding profiles, and SLA profiles to steer traffic onto SLA compliant paths.