Improve network performance with ENA Express on Windows instances
ENA Express is powered by AWS Scalable Reliable Datagram (SRD) technology.
SRD is a high performance network transport protocol that uses dynamic routing
to increase throughput and minimize tail latency. 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 optimize for latency most of the time, especially during periods when there is
no congestion on the network, Enhanced networking might be a better fit for your
network.
During periods of time when network traffic is light, you might notice a slight increase
in packet latency (tens of microseconds) when the packet uses ENA Express. During those times,
applications that prioritize specific network performance characteristics can benefit from
ENA Express as follows:
-
Processes can benefit from increased maximum single flow bandwidth from 5 Gbps to
25 Gbps within the same subnet.
-
Longer running processes should experience reduced tail latency during periods of
network congestion.
-
Processes can benefit from a smoother and more standard distribution for network
response times.
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:
-
Both sending and receiving instance types are supported. See the
Supported instance types for ENA Express
table for more information.
-
Both sending and receiving instances must have ENA Express configured. If there are differences in the configuration, you can run into situations
where traffic defaults to standard ENA transmission. The following scenario shows what can happen.
Scenario: Differences in configuration
Instance |
ENA Express Enabled |
UDP uses ENA Express |
Instance 1 |
Yes |
Yes |
Instance 2 |
Yes |
No |
In this case, TCP traffic between the two instances can use ENA Express, as both
instances have enabled it. However, since one of the instances does not use ENA Express
for UDP traffic, communication between these two instances over UDP uses standard ENA
transmission.
-
The sending and receiving instances must run in the same subnet.
-
The network path between the instances must not include middleware boxes. ENA Express
doesn't currently support middleware boxes.
-
To utilize full bandwidth potential, use driver version 2.2.9 or higher.
If any requirement is unmet, the instances use the standard TCP/UDP protocol but without
SRD 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.
Supported instance types for ENA Express
The following table contains instance types that support ENA Express.
Instance family |
Instance type |
Instance size |
Architecture |
General purpose |
m6i |
m6i.32xl, m6i.metal |
x86_64 |
General purpose |
m6id |
m6id.32xl, m6id.metal |
x86_64 |
Compute optimized |
c6i |
c6i.32xl, c6i.metal |
x86_64 |
Compute optimized |
c6id |
c6id.32xl, c6id.metal |
x86_64 |
Memory optimized |
r6i |
r6i.32xl, r6i.metal |
x86_64 |
Memory optimized |
r6id |
r6id.32xl, r6id.metal |
x86_64 |
Storage optimized |
i4i |
i4i.32xl, i4i.metal |
x86_64 |
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}'