# Does the Digi One SP using Realport have a heartbeat?

**URL:** <https://forums.digi.com/t/does-the-digi-one-sp-using-realport-have-a-heartbeat/19194>\
**Category:** Realport\
**Tags:** digi-one-sp, bandwidth, digi-one, keepalive, realport\
**Created:** [February 21, 2018, 3:50pm UTC](https://forums.digi.com/t/does-the-digi-one-sp-using-realport-have-a-heartbeat/19194 "2018-02-21T15:50:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![bammin](https://avatars.discourse-cdn.com/v4/letter/b/c0e974/32.png) [@bammin](https://forums.digi.com/u/bammin)\
**Post date:** [February 21, 2018, 3:50pm UTC](https://forums.digi.com/t/does-the-digi-one-sp-using-realport-have-a-heartbeat/19194/1 "2018-02-21T15:50:17Z")

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I’m using Realport on a Digi One SP. Using Wireshark I’ve noticed that the Digi One appears to send some sort of a keepalive to the client (the client is running on Debian). The client responds with a TCP ACK, and that completes the keepalive. This happens every 10 seconds. This happens even if I unplug the Digi One serial cable, so that is why I’m pretty sure this is some sort of a Digi keepalive.

Is there a way to turn this down? The Digi is running over an LTE network and I want to dramatically reduce bandwidth usage. As it is, these keepalives use about 2 MB per day.

edit: Just read in the documentation about this keepalive, and yes indeed this is the cause. The documentation recommends to consider using TCP keepalives instead. I’ve read the section on TCP keepalives, but I’m interested in getting you guy’s take on what would be best practice, considering I’m trying to limit bandwidth usage over the cellular network, but also obviously want the Digi One to be reliable.

edit 2: So I disabled both realport keepalives AND TCP keep alives for fun, but I’m now getting a keepalive every 20 seconds. I understand I probably want TCP keepalives of some sort, but I’m just trying to test the behavior. Below is my config:

# Digi One SP Version 82000774\_W1 02/16/2016

set config dhcp=off  
set config myname=“” domain=“”  
set config ip=192.168.10.2 submask=255.255.255.0  
set config gateway=192.168.10.1  
set config realport=771 sockets=2000 redirect=ignore tbreak=std  
set config optimize=throughput  
set keys prevcmd=^P nextcmd=^N forwchar=^F backchar=^B  
set config boothost=0.0.0.0 bootfile=“” tftpboot=no  
set config pmtelnet=off  
set config rpexclusive=off  
set config rpkeepalives=off  
set config cache\_dns=on  
set ethernet speed=auto duplex=half  
set config rarp=on  
set config ping-arp=on  
set tcpip keepalive\_active=off keepalive\_idle=02:00:00 keepalive\_byte=off  
set tcpip probe\_cnt=5 probe\_interval=30  
set tcpip tcp\_ttl=64 ip\_ttl=64  
set tcpip rto\_min=100 rto\_max=240  
set tcpip garp=3600 arp\_ttl=1200  
set profile range=1 profile=realport  
set line range=1 parity=N csize=8 error=ignore  
set line range=1 baud=9600 stopb=1 break=ignore inpck=off istrip=off onlcr=off otab=off  
set flow range=1 ixon=off aixon=off ixoff=off ixany=off itoss=off altpin=off forcedcd=off  
set flow range=1 dtr=off cts=off dcd=off dsr=off  
set flow range=1 ri=off  
set flow range=1 pre-delay=0 post-delay=0  
set flow range=1 rts=off

set keys range=1 xon=^Q xoff=^S xona=^Q xoffa=^S lnext=^V

set port range=1 dev=rp sess=4 termtype=“vt100” edelay=1 auto=off bin=off  
set port range=1 uid=none group=none dport=none  
set port range=1 dest=none  
set port range=1 scriptname=none  
set port range=1 keepalive=off flushstchar=default autoservice=default  
set port range=1 autodrain=off  
set port range=1 idletime=0