Digi Connect Series User Manual

Latency tuning Step 4: Optimize thenetwork and transport layers
Digi Connect Family and ConnectPort TSFamily
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Command Option Description
set network garp=30-3600
(seconds)
Frequency of Gratuitous ARP(GARP) announcements, which are a
broadcast announcement to the network of a device’sMAC
addressand the IPaddress. These allow the network to update its
ARPcache tables without performing an ARPrequest on the
network. GratuitousARPannouncements can affect latency in a
limited way, because some systems stall or dispose of data that is
transmitted during an ARPcache refresh. If this happens, setting
the Gratuitous ARPfrequency to bemore often than the problem
system’stime-to-live variable can cause it to refresh the cache
without needing to perform a request.
set network rto_min=30-
1000
TheTCPmaximum retransmission timeout (RTO) in seconds. TCP
usesprogressively larger retransmit values, starting at a minimum
valuecalculated from a sliding window of ACKresponse round-
trip timesbounded at the bottom by rto_min. Essentially, rto_
min isnot necessarily the timeout that will be used as the starting
retransmit timeout, but the smallest such valuethat could be
used. This affects latency, because lowering rto_min can ensures
that retransmits, if they occur, take placein lesstime. By
occurring sooner, the network can recover lost data in lesstime at
the expense of possibly retransmitting data still in-flight or
successfully received by the other side, but unacknowledged due
to a “delayed ACK” mechanism or something similar.
set service range=range Theindex number associated with the service.
set service nodelay={on|off} Allows unacknowledged or smaller-than-maximum-segment-sized
data to be sent for the specified range of network services.
nodelay=off disablesNagle’salgorithm, which ison by default,
for some TCPservices. Nagle's algorithm reduces the number of
small packetssent. It establishes not sending outgoing data when
there is unacknowledged sent data, or isless-than-maximum
segment size (typically around 1500 bytesfor Ethernet) worth of
data to be sent. While Nagle's algorithm allows efficient data
transmission, there are timeswhere it isdesirable to disable it.
set service delayed_ack=0-
1000
Time, in milliseconds, to delay sending ACK packets in response
to received data for the specified range of network services.
Default is200 milliseconds. Setting this option to 0(zero) sends
an ACKpacket back acknowledge the received data immediately.
Setting this option to any other valuethan 0 meansthat the ACK
packet will be sent after the specified time. If the network services
generate new data during that time, the ACKpacket issent along
with the data packet. You can use thissetting to avoid congestion
and reduce network traffic, However, do not change this option
from its default setting unlessyou havea solid understanding of
network services and data transmission, or have been instructed
to the change.
Considerations for using latency-related command options
There are several considerationsfor using these latency-related command options:

Digi Connect Series Specifications

General

Category	Network Router
Series	Connect
Manufacturer	Digi
Cellular Technology	4G LTE, 3G
Serial Ports	1-2 (varies by model)
Security	VPN, Firewall
Management	Web, CLI, SNMP

Summary

About this guide

Important safety information

Essential safety precautions for electrical and environmental hazards.

Where to find information

Locating additional product and feature information and support resources.

Digi Connect and ConnectPort TS Family Features

User interfaces

Overview of interfaces for device configuration, monitoring, and administration.

Network services

Managing access to device network services for security and performance.

IP protocol support

Details on supported TCP/IP protocols and serial data over TCP/UDP.

Security features in Digi devices

Configuration of secure access, authentication, and encryption methods.

Get Started with Your Device

Hardware setup and initial connection

Verifying components and connecting hardware for ConnectPort TS and ES devices.

Assigning an IP Address

Methods for assigning IP addresses via DHCP, Auto-IP, or CLI.

Signing in to the Web Interface

Accessing the device's web interface using a browser or utility.

Device Configuration Overview

Configuration capabilities

Overview of settings for network, serial ports, alarms, and security.

Web interface and CLI access

Using the web interface and accessing the command-line interface.

Device administration

Performing administrative tasks like file management and firmware updates.

Configuring Network Settings

IP settings

Configuring IP addresses, subnet masks, and gateways for network connectivity.

Wi-Fi settings

Settings for Wi-Fi LAN, security, and 802.1x authentication.

Network Services Settings

Enabling/disabling network services and managing default port numbers.

Serial Ports Configuration

Select Port Profile

Choosing port profiles like Console Management, RealPort, or Serial Bridge.

RealPort Configuration

Mapping COM/TTY ports for virtual connections using RealPort software.

System Configuration

SNMP Settings

Managing SNMP for network device monitoring and configuration.

Date and Time Settings

Setting device date, time, and time source for accurate logging.

RADIUS authentication

Configuring RADIUS servers for user authentication and profile management.

User Management and Access Control

User Configuration

Setting up user login credentials and passwords.

User Access and Permissions

Defining user access to interfaces and feature permissions.

Remote Manager Integration

Remote Manager settings

Configuring device connection and management via Digi Remote Manager.

IPv6 support

Understanding IPv6 addressing and its implementation on Digi devices.

Hardware and System Status

System status LEDs

Understanding LED indicators for system status, link activity, and diagnostics.

Rack Mounting considerations

Guidelines for safely installing devices in equipment racks.

Specifications and Certifications

Hardware specifications

Technical details on environmental, power, and dimension requirements.

Wireless networking features

Key Wi-Fi features for configuration, including security and modes.

Troubleshooting

Replace Connect ES time-lag fuses

Procedure for replacing time-lag fuses in Connect ES devices.

Troubleshooting resources

Resources like knowledge base, forums, and support tickets for issue resolution.