User guide

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9 Downlink and Uplink transfer using iperf
For running Downlink and Uplink test, iperf can be used on both sides: Core network and LTE
UE simulator.
However, when several instances of UE are used, network namespace (netns) is required at UE
side.
9.1 Introducing Linux Network Namespaces
A network namespace is logically another copy of the network stack, with its own routes, firewall
rules, and network devices. In UE config file, when parameter tun_setup_script: "ue-ifup"
is present, each UE gets its own (logical) Tun interface created.
You can then use it to select the UE PDN to be used for transmitting and receiving data, as
described in the section below
The useful commands are :
• ip netns list - show all of the named network namespaces
• ip netns exec ueX cmdX - Execute a command within the namespace of a UE.
9.2 Uplink test
For sending uplink traffic from multiple UEs with iperf:
• Set tun_setup_script: "ue-ifup", under ue_list (in ue.cfg file), for each UE in order
to create a TUN interface for each UE PDN
• Start LTE UE service (service lte start), switch to LTE screen (screen -x lte) and
power on UEs (power_on <UE_ID>)
• On EPC side, run iperf command iperf -s -u -i 1
• On UE side, in linux shell, type ip netns list to list all network namespaces
[root@localhost ~]# ip netns list
ue2
ue1
• Select the targeted UE and generate uplink IP traffic from this UE by running the iperf
command within its namespace
Example: ip netns exec ue2 iperf -c 192.168.3.1 -u -b 150M -i 1 -t 100
9.3 Downlink test
For sending downlink traffic to multiple UE using iperf:
• Set tun_setup_script: "ue-ifup", under ue_list (in ue.cfg file), for each UE in order
to create a TUN interface for each UE PDN
• Start LTE UE service (service lte start), switch to LTE screen (screen -x lte) and
power on UEs (power_on <UE_ID>)
• Once registered, get eRAB IP address of each UE by running ue command in LTE screen
(ue) ue
# UE_ID CL RNTI RRC_STATE EMM_STATE #ERAB IP_ADDR
0 1 0 51 idle registered 1 192.168.2.2
1 2 0 50 idle registered 1 192.168.2.6
• On EPC side, run iperf command to start Downlink transfer and select the targeted UE by
using its eRAB IP address. Example :
iperf -c 192.168.2.2 -u -b 150M -i 1 -t 100