Improve network performance with ENA Express on Linux instances
With ENA Express, you can communicate between two
EC2 instances in the same subnet.
Benefits of ENA Express
-
Increases the maximum bandwidth a single flow can use from 5 Gbps to
25 Gbps within the subnet.
-
Reduces tail latency of network traffic between EC2 instances, especially
during periods of high network load.
-
Detects and avoids congested network paths.
-
Handles some tasks directly in the network layer, such as packet reordering
on the receiving end, and most retransmits that are needed. This frees up the
application layer for other work.
If your application sends or receives a high volume of packets per second, and
needs to minimize P50 latency, Enhanced networking might be a better fit for your
network.
Prerequisites
To ensure that ENA Express can operate effectively, update the following settings for
your instance.
-
If your instance uses jumbo frames, run the following command to
set your maximum transmission unit (MTU) to 8900
.
[ec2-user ~]$
sudo ip link set dev eth0
mtu 8900
-
Increase the receiver (Rx) ring size, as follows:
[ec2-user ~]$
ethtool -G device
rx 8192
How ENA Express works
SRD technology uses a packet spraying mechanism to distribute load and avoid network
congestion. It distributes packets for each network flow across different AWS network
paths, and dynamically adjusts distribution when it detects signs of congestion. It also
manages packet reordering on the receiving end.
To ensure that ENA Express can manage network traffic as intended, sending and receiving
instances and the communication between them must meet all of the following requirements:
If any requirement is unmet, the instances use the standard ENA driver to communicate.
Amazon EC2 refers to the relationship between an instance and a network interface that's
attached to it as an attachment. ENA Express settings apply to
the attachment. If the network interface is detached from the instance, the
attachment no longer exists, and the ENA Express settings that applied to it are no
longer in force. The same is true when an instance is terminated, even if the
network interface remains.
To ensure that your instance network driver is configured for optimum performance,
review the recommended best practices for ENA drivers. These best practices apply to ENA Express,
as well. For more information, see the ENA
Linux Driver Best Practices and Performance Optimization Guide on the GitHub website.
Supported instance types for ENA Express
ENA Express is supported by the c6gn.16xl instance type.
List and view ENA Express settings
This section covers how to list and view ENA Express information from the
AWS Management Console or from the AWS CLI. For more information, choose the tab that matches
the method you'll use.
- Console
-
This tab covers how to find information about your current ENA Express
settings and to view instance type support in the AWS Management Console.
View instance type support
Open the Amazon EC2 console at
https://console.aws.amazon.com/ec2/.
-
In the left navigation pane, choose Instance types.
-
Select an instance type to see the details for that instance. You can choose the
Instance type link to open the detail
page, or you can select the checkbox on the left side of the list to view details in the
detail pane at the bottom of the page.
-
In the Networking tab or that section on the
detail page, ENA Express support shows a true or
false value to indicate if the instance type supports this feature.
View settings from the Network interface list
Open the Amazon EC2 console at
https://console.aws.amazon.com/ec2/.
-
In the left navigation pane, choose Network interfaces.
-
Select a network interface to see the details for that instance. You can choose the
Network interface ID link to open the
detail page, or you can select the checkbox on the left side of the list to view details in the
detail pane at the bottom of the page.
-
In the Network interface attachment section on the
the Details tab or detail page, review settings for
ENA Express and ENA Express UDP.
View settings from instances
Open the Amazon EC2 console at
https://console.aws.amazon.com/ec2/.
-
In the left navigation pane, choose Instances.
-
Select an instance to see the details for that instance. You can choose the
Instance ID link to open the detail
page, or you can select the checkbox on the left side of the list to view details in the
detail pane at the bottom of the page.
-
In the Network interfaces section on the
Networking tab, scroll right to review settings for
ENA Express and ENA Express UDP.
- AWS CLI
-
This tab covers how to find information about your current ENA Express
settings and to view instance type support in the AWS CLI.
Describe instance types
For information on instance type settings for a specific instance type, run the describe-instance-types command in
the AWS CLI, and substitute the instance type as follows:
[ec2-user ~]$
aws ec2 describe-instance-types --instance-types m6i.metal
{
"InstanceTypes": [
{
"InstanceType": "m6i.metal",
"CurrentGeneration": true,
...
},
"NetworkInfo": {
...
"EnaSrdSupported": true
},
...
}
]
}
Describe network interfaces
For information on instance type settings, run the describe-network-interfaces command
in the AWS CLI as follows:
[ec2-user ~]$
aws ec2 describe-network-interfaces
{
"NetworkInterfaces": [
{
"Association": {
....IPs, DNS...
},
"Attachment": {
"AttachTime": "2022-11-17T09:04:28+00:00",
"AttachmentId": "eni-attach-0ab1c23456d78e9f0",
"DeleteOnTermination": true,
"DeviceIndex": 0,
"NetworkCardIndex": 0,
"InstanceId": "i-0abcd123e456fabcd",
"InstanceOwnerId": "111122223333",
"Status": "attached",
"EnaSrdSpecification": {
"EnaSrdEnabled": true,
"EnaSrdUdpSpecification": {
"EnaSrdUdpEnabled": true
}
}
},
...
"NetworkInterfaceId": "eni-0d1234e5f6a78901b",
"OwnerId": "111122223333",
...
}
]
}
You can configure ENA Express for supported EC2 instance types without needing to
install any additional software. This section covers how to configure ENA Express
from the AWS Management Console or from the AWS CLI. For more information, choose the tab that matches
the method you'll use.
- Console
-
This tab covers how to manage ENA Express settings for network interfaces
that are attached to an instance.
Manage ENA Express from the Network interface list
Open the Amazon EC2 console at
https://console.aws.amazon.com/ec2/.
-
In the left navigation pane, choose Network interfaces.
-
Select a network interface that is attached to an instance. You can choose the
Network interface ID link to open the
detail page, or you can select the checkbox on the left side of the list.
-
Choose Manage ENA Express from the
Action menu at the top right side of the
page. This opens the Manage ENA Express dialog,
with the selected network interface ID and current settings displayed.
If the network interface you selected is not attached to
an instance, this action does not appear in the menu.
-
To use ENA Express, select the Enable
check box.
-
When ENA Express is enabled, you can configure UDP settings. To use
ENA Express UDP, select the Enable
check box.
-
To save your settings, choose Save.
Manage ENA Express from the Instance list
Open the Amazon EC2 console at
https://console.aws.amazon.com/ec2/.
-
In the left navigation pane, choose Instances.
-
Select the instance that you want to manage. You can choose the Instance
ID to open the detail page,
or you can select the checkbox on the left side of the list.
-
Select the Network interface to configure
for your instance.
-
Choose Manage ENA Express from the
Action menu at the top right side of the
page.
-
To configure ENA Express for a network interface that's attached to your
instance, select it from the Network interface list.
-
To use ENA Express for the selected network interface
attachment, select the Enable check box.
-
When ENA Express is enabled, you can configure UDP settings. To use
ENA Express UDP, select the Enable
check box.
-
To save your settings, choose Save.
Configure ENA Express when you attach a network interface to an EC2 instance
Open the Amazon EC2 console at
https://console.aws.amazon.com/ec2/.
-
In the left navigation pane, choose Network interfaces.
-
Select a network interface that is not attached to an instance
(Status is
Available). You can choose the
Network interface ID link to open the
detail page, or you can select the checkbox on the left side of the list.
-
Select the Instance that you'll attach to.
-
To use ENA Express after you attach the network interface
to the instance, select the Enable check box.
-
When ENA Express is enabled, you can configure UDP settings. To use
ENA Express UDP, select the Enable
check box.
-
To attach the network interface to the instance and save your ENA Express
settings, choose Attach.
- AWS CLI
-
This tab covers how to configure ENA Express settings in the AWS CLI.
Configure ENA Express when you attach a network interface
To configure ENA Express when you attach a network interface to an instance, run the
attach-network-interface command in
the AWS CLI, as shown in the following examples:
Example 1: Use ENA Express for TCP traffic, but not for
UDP traffic
In this example, we configure EnaSrdEnabled
as true, and
we allow EnaSrdUdpEnabled
to default to false.
[ec2-user ~]$
aws ec2 attach-network-interface --network-interface-id eni-0123f4567890a1b23
--instance-id i-0f1a234b5cd67e890
--device-index 1 --ena-srd-specification 'EnaSrdEnabled=true'
{
"AttachmentId": "eni-attach-012c3d45e678f9012"
}
Example 2: Use ENA Express for both TCP traffic and UDP traffic
In this example, we configure both EnaSrdEnabled
and EnaSrdUdpEnabled
as true.
[ec2-user ~]$
aws ec2 attach-network-interface --network-interface-id eni-0123f4567890a1b23
--instance-id i-0f1a234b5cd67e890
--device-index 1 --ena-srd-specification 'EnaSrdEnabled=true,EnaSrdUdpSpecification={EnaSrdUdpEnabled=true}'
{
"AttachmentId": "eni-attach-012c3d45e678f9012"
}
Update ENA Express settings for your network interface attachment
To update ENA Express settings for a network interface that's attached to an instance,
run the modify-network-interface-attribute
command in the AWS CLI, as shown in the following examples:
Example 1: Use ENA Express for TCP traffic, but not for UDP traffic
In this example, we configure EnaSrdEnabled
as true, and
we allow EnaSrdUdpEnabled
to default to false if it has never
been set previously.
[ec2-user ~]$
aws ec2 modify-network-interface-attribute --network-interface-id eni-0123f4567890a1b23
--ena-srd-specification 'EnaSrdEnabled=true'
Example 2: Use ENA Express for both TCP traffic and UDP traffic
In this example, we configure both EnaSrdEnabled
and EnaSrdUdpEnabled
as true.
[ec2-user ~]$
aws ec2 modify-network-interface-attribute --network-interface-id eni-0123f4567890a1b23
--ena-srd-specification 'EnaSrdEnabled=true,EnaSrdUdpSpecification={EnaSrdUdpEnabled=true}'
Example 3: Stop using ENA Express for UDP traffic
In this example, we configure EnaSrdUdpEnabled
as false.
[ec2-user ~]$
aws ec2 modify-network-interface-attribute --network-interface-id eni-0123f4567890a1b23
--ena-srd-specification 'EnaSrdUdpSpecification={EnaSrdUdpEnabled=false}'
Monitor ENA Express performance
After you've enabled ENA Express for the network interface attachments on both the sending
instance and receiving instance, you can use ENA Express metrics to help ensure that
your instances take full advantage of the performance improvements that SRD
technology provides.
Verify ENA Express settings for an instance
To verify the current ENA Express settings for the network interface attachment on your instance,
run the ethtool
command to list ENA Express metrics, and take note of the value of the
ena_srd_mode
metric. Values are as follows:
After you've enabled ENA Express for the network interface attachment on an instance, the
sending instance initiates communication with the receiving instance, and SRD
detects if ENA Express is operating on both the sending instance and the reciving
instance. If ENA Express is operating, the communication can use SRD transmission.
If ENA Express is not operating, the communication falls back to standard ENA
transmission. To confirm if packet transmission is using SRD, you can compare the
number of eligible packets (ena_srd_eligible_tx_pkts
metric) to the
number of SRD packets transmitted (ena_srd_tx_pkts
metric) during a
given time period.
You can monitor your SRD resource utlization using the the
ena_srd_resource_utilization
metric. If your instance is close to
exhausting its SRD resources, you'll know it's time to scale out the
instance.
For more information about ENA Express metrics, see
Metrics for ENA Express.