I have the following topology 1, where there are 4 Cisco Routers deployed in each VPC. I am able to ping and generate traffic from Endpoint1: to Endpoint2: where the traffic passes through a set of paths called Segment Routing which I have defined in the router R1 e.g., (Endpoint1, R1, R2, R3, R2, R1, R2, R3, Endpoint2).

I have got apache installed in both instances, then I put the file that I'd like to download from the client side in the server Endpoint1 and put into a folder /var/www/files/. Note that, both instances endpoints are in different VPCs.

I aim to send 100Mb file from Endpoint1 to Endpoint2.

In the client instance Endpoint2, I did the following:


I tried also:


the logs show: - - [19/Jun/2019:13:20:24 +0000] "GET /files/ubuntu-18.04.2-live-server-amd64.iso HTTP/1.1" 200 295317 "-" "curl/7.58.0"

But both are taking long time, and here what I got from Endpoint2

Connecting to connected.
HTTP request sent, awaiting response... 

this is The iptables of Endpoint1 is the following:

ubuntu@ip-172-0-1-11:~$ sudo iptables -L -n -v

Chain INPUT (policy ACCEPT 517 packets, 35198 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 425 packets, 70378 bytes)
 pkts bytes target     prot opt in     out     source               destination         

I tried with iperf and it sends the traffic normally. On the server side:

ubuntu@ip-172-0-1-11:~$ iperf -s -u

and the client:

iperf -c -u -b 20m 

UDP buffer size:  208 KByte (default)
[  3] local port 38402 connected with port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  23.8 MBytes  20.0 Mbits/sec
[  3] Sent 17008 datagrams
[  3] Server Report:
[  3]  0.0-10.0 sec  23.8 MBytes  20.0 Mbits/sec   0.000 ms   20/17008 (0%)

I even tried telnet. It seems that there is a connection between server and client. As well as the client side.

ubuntu@ip-172-2-1-10:~$ telnet 80
Connected to

Seems everything is working, except downloading the file.

  • It sort of sounds like an MTU issue, but it could also be the fact that you used global IP addresses that don't belong to you, instead of RFC1918 addresses. – Michael Hampton Jun 23 '19 at 5:45
  • @MichaelHampton well, I'm working within VPC private network. Those are private addresses which are given by AWS. – Tim Luka Jun 24 '19 at 9:38
  • 1
    @MichaelHampton you were right! It turns out it was MTU issue due the large size of the file. Is there any way to send the file like partly? I mean send part of the file until the highest value of that MTU then make a pause for couple of seconds till the end of file? – Tim Luka Jun 24 '19 at 11:33

As Best i know :

instead of struggling with iptables stuff,

Execute below command where your HTTPD / Apache web-servers installed

iptables -F

Have a great day future friend .!


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