How can I simulate WAN latency with tc netem qdisc?_android does not support qdisc 'netem-优快云博客

本文介绍如何使用tc工具在Red Hat Enterprise Linux 6.x和7.x上模拟WAN延迟，通过设置特定应用（监听端口1521）在局域网连接上的往返时间延迟，为系统1和系统2之间的通信引入约148毫秒的延迟。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

https://access.redhat.com/solutions/1983003

SOLUTION 已验证 - 已更新 2018年八月14日22:28 -

English

环境

Red Hat Enterprise Linux 6.x
Red Hat Enterprise Linux 7.x

问题

Unable to simulate latency using tc netem qdisc (delay never works)
Need to simulate WAN delays on LAN connection for specific Application

决议

Introducing delay of 74ms one end delay (~148ms RTT)
System1: 10.10.10.1 source port 1521 (Application's listening port)
System2: 10.10.10.2

Creating rules introducing delay from System1 towards System2:

Raw

System1# tc qdisc add dev eth0 root handle 1: prio
System1# tc qdisc add dev eth0  parent 1:1 handle 2: netem delay 74ms
System1# tc filter add dev eth0 protocol ip u32 match ip sport 1521 0xffff match ip dst 10.10.10.2/32 flowid 1:1

Creating rules introducing delay from System2 towards System1:

Raw

System2# tc qdisc add dev eth0 root handle 1: prio
System2# tc qdisc add dev eth0  parent 1:1 handle 2: netem delay 74ms
System2# tc filter add dev eth0 protocol ip u32 match ip dport 1521 0xffff match ip dst 10.10.10.1/32 flowid 1:1

Checking results:

Raw

System1# nping --tcp -p 1521 10.10.10.2

Starting Nping 0.6.47 ( http://nmap.org/nping ) at 2015-10-08 14:04 AEST
SENT (0.0259s) TCP 10.10.10.1:3196 > 10.10.10.2:1521 S ttl=64 id=41690 iplen=40  seq=3092419819 win=1480 
RCVD (0.1748s) TCP 10.10.10.2:1521 > 10.10.10.1:3196 RA ttl=61 id=0 iplen=40  seq=0 win=0 
SENT (1.0260s) TCP 10.10.10.1:3196 > 10.10.10.2:1521 S ttl=64 id=41690 iplen=40  seq=3092419819 win=1480 
RCVD (1.1747s) TCP 10.10.10.2:1521 > 10.10.10.1:3196 RA ttl=61 id=0 iplen=40  seq=0 win=0 
SENT (2.0272s) TCP 10.10.10.1:3196 > 10.10.10.2:1521 S ttl=64 id=41690 iplen=40  seq=3092419819 win=1480 
RCVD (2.1761s) TCP 10.10.10.2:1521 > 10.10.10.1:3196 RA ttl=61 id=0 iplen=40  seq=0 win=0 
SENT (3.0282s) TCP 10.10.10.1:3196 > 10.10.10.2:1521 S ttl=64 id=41690 iplen=40  seq=3092419819 win=1480 
RCVD (3.1770s) TCP 10.10.10.2:1521 > 10.10.10.1:3196 RA ttl=61 id=0 iplen=40  seq=0 win=0 
SENT (4.0293s) TCP 10.10.10.1:3196 > 10.10.10.2:1521 S ttl=64 id=41690 iplen=40  seq=3092419819 win=1480 
RCVD (4.1781s) TCP 10.10.10.2:1521 > 10.10.10.1:3196 RA ttl=61 id=0 iplen=40  seq=0 win=0 

Max rtt: 148.871ms | Min rtt: 148.729ms | Avg rtt: 148.786ms
Raw packets sent: 5 (200B) | Rcvd: 5 (230B) | Lost: 0 (0.00%)
Nping done: 1 IP address pinged in 4.19 seconds
#