Reserve Minimum Bandwidth for Conduit WAN Links
Certain network conditions cause congestion on a defined WAN link or path. When this congestion occurs, the appliance would reduce the amount of conduit data being forwarded on that WAN link. The appliance would reduce the usage rate down to its lowest defined rate (in certain cases) which was 80 kbps. When this occurred, there could be a performance impact to user data that was inside the conduit. For instance, 80 kbps would typically not even support a typical VoIP phone call. This unforeseen state could be caused by some external WAN-facing router that is oversubscribed with no configuration options of guarantying the appliance its defined usable rate. To overcome this issue, Oracle SD-WAN Edge release 2.3 allows the user to define a WAN link minimum rate - which is the lowest usage rate a WAN link will use during times of congestion. This will guarantee the appliance will continue to send no less than this defined value on the WAN link.
There are a number of design considerations to be aware of for this capability:
- Can be applied to a specific conduit on a WAN link only
- Must consider defined usage rates
- If congestion is consistent, the user should resolve the congestion issue on the router or firewall
An example of defining this minimum usage rate:
add virtual_wan_link name=Client-1-Link2
{
set properties
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virtual_interface_name=CL1VL11 virtual_ip_addr=10.1.20.12 |
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gw_ip_addr=10.1.20.5 |
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} |
wan_ingress_physical_rate_kbps=3000 wan_egress_physical_rate_kbps=3000 wan_ingress_permitted_rate_kbps=3000 wan_egress_permitted_rate_kbps=3000 enable_public_ip_learning=true tracking_ip_addr=10.1.20.15; add conduit_usage remote_site_name=NCN-Site wan_egress_rate_pct=100.0 wan_ingress_rate_pct=100.0 minimum_reserved_bandwidth_kbps=400; |
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minimum_reserved_bandwidth_kbps = Number (80
The minimum amount of bandwidth that this usage will be reduced to during on demand scheduling. The default value for conduit links in shown above.
As we can see from the above configuration example, this option is applied under the WAN link and conduit usage. Once the specific WAN link is defined, the user can proceed to the conduit usage section where the minimum bandwidth option can be defined.
Configurable Congestion Control per WAN Link
The congestion threshold defines the period of time the appliance determines the WAN link is congested – if there is congestion for the defined period, it will then proceed into a congestion avoidance state. This is accomplished by reducing the amount of data sent on a WAN link. Sending less conduit data on a WAN link should result in the probability of the congested state clearing itself. The default value for this configuration option is 20 ms. (20000- value – default).
If the user chooses to change this value, it is recommended they contact a Oracle representative for specific values to use. If they decide to change the value to avoid the appliance from acting on a congestion state, the user would increase the value for example, if the value is increased to 2000000 – this would instruct the appliance that congestion must occur for a period of 2 seconds before the congestion avoidance algorithm is invoked. In traditional networks, 2 seconds of congestion would not happen. Since congestion is not detected the congestion avoidance algorithm is not enabled and the appliance continues sending data up to the defined usable rate.
add virtual_wan_link name=Client-1-Link2
{
set properties
virtual_interface_name=CL1VL11
virtual_ip_addr=10.1.20.12
gw_ip_addr=10.1.20.5
wan_ingress_physical_rate_kbps=3000
wan_egress_physical_rate_kbps=3000
wan_ingress_permitted_rate_kbps=3000
wan_egress_permitted_rate_kbps=3000
enable_public_ip_learning=true
congestion_threshold_us_per_s_us=200000 tracking_ip_addr=10.1.20.15; .
.
.
}
With the congestion avoidance algorithm disabled, the Oracle will send data up to the configured usage rate. There could be a negative impact to other data flows within the network infrastructure depending on bandwidth allocation. The Oracle assumes that the defined usage rate is a guaranteed rate and attempts to send data at that defined rate as required. Users must consider this when using this new parameter.
Path Eligible Setting for Traffic Types
The Path Eligible/Ineligible options allow users to specify a certain traffic class to be eligible or ineligible for a specific WAN link. By default, all WAN links are eligible for all traffic classes. When a WAN link is ineligible for a traffic class internally, the appliance will add 150 ms latency to the defined WAN link. Depending on the WAN links in the configuration, this may only reduce the use of that WAN link under normal conditions. When traffic is queued up, the WAN link could be used by the appliance for the ineligible class if circumstances dictate.
The configuration parameters are shown below:
set properties
virtual_interface_name=CL4VL44
virtual_ip_addr=10.4.50.12
gw_ip_addr=10.4.50.5
wan_ingress_physical_rate_kbps=10000
wan_egress_physical_rate_kbps=10000
wan_ingress_permitted_rate_kbps=10000 wan_egress_permitted_rate_kbps=10000 wan_ingress_realtime_eligible=true wan_ingress_interactive_eligible=true wan_egress_realtime_eligible=true wan_egress_interactive_eligible=true wan_ingress_bulk_eligible=true
wan_egress_bulk_eligible=true;
This configuration example displays the default option. When reviewing a standard configuration with all paths eligible, these options will not appear in the configuration file.
They are displayed above so the user can understand what commands to use for these options. To verify the settings, the user can use the Oracle SD-WAN Edge QoS reports to view and verify that a specific WAN link is limiting a traffic class from that WAN link. Users should consult a Oracle representative if they believe they need this feature enabled for a specific WAN link.