ICMP fragmentation

[Vijay Ram]

Hi Team,

I'm trying to use v3.0 stateless code to test ICMP fragmentation. I used the below below scapy & fragment a 2000 bytes payload in 4 chunks. I explicitly set the IP header Identification field in scapy. Dumped the scapy & ensured ID field is same for all fragments but when I try to simulate the test with TRex I could see Identification field getting auto set for each fragment of a single packet which is incorrect. Does TRex changes the ID field against the one set via scapy?

Wireshark capture

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with regards
Vijayram.P

[hanoh haim]

Hi Vijay, 

FlowStats stream overide some ip field to mark the packets as a FlowStats/LatencyStream, have a look into the doc which field is used. This could explain the issue. 

Thanks

Hanoh

 

[Vijay Ram]

Hi Hanoh,

I have got another query in ICMP fragmentation. I have set the ICMP ID field in scapy since each ICMP packet should have a non-zero ID field to let the packet flow out via router FW.

Since I want to create high bandwidth flows, I tried "update -m 1mbps" in TRex console to bump up the traffic. I could indeed see 1mb traffic hitting DuT router LAN but all contain the same ICMP ID/sequence number field & hence only one response I could find. 

When we enter "update -1 mbps" to increases the load, how to ensure each packet sent have different ID/Seq # in ICMP header?

thx,

Vijayram

On Wed, Feb 14, 2024 at 1:53 PM Vijay Ram <vijayr...@gmail.com> wrote:

Thanks Hannah. I could see proper ID field moment I remove the flow stats piece of code 

Thx,

Vijayram 

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with regards
Vijayram.P

[Vijay Ram]

Hi Hanoh,

I'm alternatively trying to see if we can replay ICMP fragmented packets. I have packet captured oversized PING packets from windows/Linux. I then tried to add PCAP into ASTF script but got an error saying PCAP doesn't contain TCP or UDP header.

So instead tried to use PCAP in stateless STL script but only the first fragment packet could be replayed but not all fragmented packets.

Is it possible to replay fragmented ICMP packets PCAP through TRex script?

Thx,

Vijayram 

[Vijay Ram]

Hi Hanoh,

Any suggestions for my question?

Thx,

Vijayram 

[Vijay Ram]

Hi Hanoh,

Could you please let me know if we can use the below alternative approach for ICMP fragmentation?

Thx,

Vijayram