How to generate packets with MTU greater than 1500 MTU

[jigs9...@gmail.com]

Hi Srivats,

I just want to know how can we generate packets with MTU size greater than 1500 MTU usin Ostinato. I tried to generate packets with MTU greater than 1500 but packets are not getting generated. 

And if I try to send packets with Greater MTU size using ping command, its working fine on the same system where Ostinato is installed. Below is the o/p using ping command.

Sending Packets:

*********************************************************************

[root@kipgen01 ~]# ping -s 2000 172.29.7.48

PING 172.29.7.48 (172.29.7.48) 2000(2028) bytes of data.

2008 bytes from 172.29.7.48: icmp_seq=1 ttl=62 time=0.748 ms

2008 bytes from 172.29.7.48: icmp_seq=2 ttl=62 time=0.499 ms

2008 bytes from 172.29.7.48: icmp_seq=3 ttl=62 time=0.576 ms

Receiving Packets:

[root@kipgen03 ~]# tshark -i eth1 src host 172.29.1.196

Running as user "root" and group "root". This could be dangerous.

Capturing on eth1

  0.000000 172.29.1.196 -> 172.29.7.48  IPv4 1514 Fragmented IP protocol (proto=ICMP 1, off=0, ID=bc8a)

  0.000021 172.29.1.196 -> 172.29.7.48  ICMP 562 Echo (ping) request  id=0x487c, seq=6/1536, ttl=62

  0.999982 172.29.1.196 -> 172.29.7.48  IPv4 1514 Fragmented IP protocol (proto=ICMP 1, off=0, ID=bc8b)

  0.999998 172.29.1.196 -> 172.29.7.48  ICMP 562 Echo (ping) request  id=0x487c, seq=7/1792, ttl=62

  1.999951 172.29.1.196 -> 172.29.7.48  IPv4 1514 Fragmented IP protocol (proto=ICMP 1, off=0, ID=bc8c)

  1.999967 172.29.1.196 -> 172.29.7.48  ICMP 562 Echo (ping) request  id=0x487c, seq=8/2048, ttl=62

  2.999936 172.29.1.196 -> 172.29.7.48  IPv4 1514 Fragmented IP protocol (proto=ICMP 1, off=0, ID=bc8d)

  2.999952 172.29.1.196 -> 172.29.7.48  ICMP 562 Echo (ping) request  id=0x487c, seq=9/2304, ttl=62

*********************************************************************

Can you please suggest me how can I generate packets with MTU greater than 1500 MTU using Ostinato. Thanks in advance.

Thanks and regards

Jigar

 

[Carlos G Mendioroz]

Jigar,
your tshark trace shows the packets are being fragmented, so you are not
generating jumbo frames at all... or am I missing something ?

-Carlos

jigs9...@gmail.com @ 07/02/2014 06:21 -0300 dixit:

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[jigs9...@gmail.com]

Carlos,

You are right. 

But when I try to send packet with 2000 MTU size (>1500)  using ping command, its sending packets in two fragments (1500+500) because my interface MTU is set to 1500.

So my concern is why I'm not able to send same packets with MTU greater than 1500 with Ostinato?   If I keep MTU greater than 1500 then it should fragment and send the packets.

So would you please suggest what should I do to send packets more than 1500 MTU with Ostinato? (if it will send with fragments than olso its ok).

Regards

Jigar

[Carlos G Mendioroz]

MTU is not packet size. Ostinato will not fragment for you AFAIK. You have to do it yourself...

jigs9...@gmail.com wrote:
>Carlos,
>
>You are right.
>
>But when I try to send packet with 2000 MTU size (>1500) using ping
>command, its sending packets in two fragments (1500+500) because my
>interface MTU is set to 1500.
>
>So my concern is why I'm not able to send same packets with MTU greater
>
>than 1500 with Ostinato? If I keep MTU greater than 1500 then it
>should
>fragment and send the packets.
>
>So would you please suggest what should I do to send packets more than
>1500
>MTU with Ostinato? (if it will send with fragments than olso its ok).
>
>
>Regards
>Jigar
>
>On Friday, 7 February 2014 15:18:45 UTC+5:30, Carlos G Mendioroz wrote:
>>
>> Jigar,
>> your tshark trace shows the packets are being fragmented, so you are
>not
>> generating jumbo frames at all... or am I missing something ?
>>
>> -Carlos
>>

>> jigs9...@gmail.com <javascript:> @ 07/02/2014 06:21 -0300 dixit:

>osti...@googlegroups.com<javascript:>

>> > To unsubscribe from this group, send email to

>> > ostinato+u...@googlegroups.com <javascript:>

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>> > an email to ostinato+u...@googlegroups.com <javascript:>.

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>>
>> --

>> Carlos G Mendioroz <tr...@huapi.ba.ar <javascript:>> LW7 EQI
>Argentina
>>

--
Carlos G Mendioroz <tr...@huapi.ba.ar> /mobile

[jigs9...@gmail.com]

Thanks for your reply.

So according to you can I send the packets of size 2000 bytes using Ostinato from the interface whose MTU is 1500 ?

And ya I'm able to send the packet of size 2000 using ping command from the interface whose MTU is 1500. (ping -s 2000 'destination address')

Thanks

Jigar

[Srivats P]

Jigar,

As Carlos said, Ostinato doesn't do fragmentation. You need to do that
manually by creating 2 streams - to do that you need a good
understanding of how IP fragmentation works and the various
fragmentation related fields in the IP header.

Srivats

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[Chris Preimesberger]

Jigar,

Ostinato can only generate Jumbo Frames on an interface that supports Jumbo frames.  You may need to change the MTU of the interface you're sending on.  Example:

On my PC, eth0's default MTU is 1500.  If I try and generate 1600B frames with Ostinato, while the MTU is set to 1500, Ostinato will not generate the frames.

If I change the interface's MTU to 1800 like this:

"sudo ifconfig eth0 mtu 1800"

Then Ostinato will generate 1600B frames on that interface.

Best regards,
Chris Preimesberger
Brooklyn Center, MN
612-669-4948

[jigs9...@gmail.com]

Thanks Srivats

  

As you said it can be done by creating two streams. But I think it will be as good as sending two packets using 2 streams so as per my understanding it won't send a single packet of greater size.(packet size is greater than interface MTU).

 

If you are pointing to something else then can you please suggest any tutorial to acheive my objective.

 

Thanks and regards

Jigar

[Carlos G Mendioroz]

Jigar,
Ostinato sends frames, not packets. If you send 2 frames that compose a
packet, you are sending a packet, right ?


jigs9...@gmail.com @ 10/02/2014 04:47 -0300 dixit:

> Thanks Srivats
>
> As you said it can be done by creating two streams. But I think it will
> be as good as sending two packets using 2 streams so as per my
> understanding it won't send a single packet of greater size.(packet size
> is greater than interface MTU).
>
> If you are pointing to something else then can you please suggest any
> tutorial to acheive my objective.
>
> Thanks and regards
> Jigar
>
> On Friday, 7 February 2014 20:22:37 UTC+5:30, Srivats P wrote:
>
> Jigar,
>
> As Carlos said, Ostinato doesn't do fragmentation. You need to do that
> manually by creating 2 streams - to do that you need a good
> understanding of how IP fragmentation works and the various
> fragmentation related fields in the IP header.
>
> Srivats
>

> On Fri, Feb 7, 2014 at 5:52 PM, <jigs9...@gmail.com <javascript:>>

> >> >> > 2008 bytes from 172.29.7.48 <http://172.29.7.48>: icmp_seq=1
> ttl=62 time=0.748 ms
> >> >> > 2008 bytes from 172.29.7.48 <http://172.29.7.48>: icmp_seq=2
> ttl=62 time=0.499 ms
> >> >> > 2008 bytes from 172.29.7.48 <http://172.29.7.48>: icmp_seq=3

> <https://groups.google.com/groups/opt_out>.

> >> >>
> >> >> --
> >> >> Carlos G Mendioroz <tr...@huapi.ba.ar <javascript:>> LW7 EQI
> >> >Argentina
> >> >>
> >>
> >> --
> >> Carlos G Mendioroz <tr...@huapi.ba.ar> /mobile
> >
> > --
> > Get Ostinato News and Updates on Twitter - Follow @ostinato
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>
>
>
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> @ostinato
>

--
Carlos G Mendioroz <tr...@huapi.ba.ar> LW7 EQI Argentina

[Srivats P]

To further clarify the difference between "packet" and "frame" -

A "packet" is at Layer 3 while "frame" is at Layer 2.

When layer 3 (e.g. IP) tries to send a "packet" whose size is greater
than the Interface MTU, it fragments the packet into multiple L2
"frames" each of which will be sized such that it is less than the
interface MTU.

It is not possible to send a "frame" larger than the interface MTU.
The only way to send a "packet" larger than the interface MTU is to
fragment into multiple smaller "frames". Ostinato does not have
capability to fragment. You can simulate the fragmentation by creating
multiple streams (each corresponding to a "frame") provided you fill
in the fragmentation fields in the IP header correctly - not
recommended unless you understand how fragmentation works and are
comfortable with it.

SRivats

[jigs9...@gmail.com]

Thanks Srivats

[chowdhur...@gmail.com]

[John Doe]

Hi pal. You want to generate jumbo frames? If yes, then you should turn on this feature in the settings of NIC driver. I used to generate jumbos with Ostinato, it does work well though Ostinato show you a warning when you set frame length more than 1518. 

Jumbos can be turned on via the compmgmt on the Windows machine.

Отправлено с моего смартфона BlackBerry 10.

От: chowdhur...@gmail.com Отправлено: суббота, 23 сентября 2017 г., 7:04 Кому: ostinato Тема: [ostinato] Re: How to generate packets with MTU greater than 1500 MTU

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[Carlos G Mendioroz]

The ping packets are being fragmented, so no packets are being sent with
MTU > 1500 there...

chowdhur...@gmail.com @ 23/09/2017 00:26 -0300 dixit:

>
>
> On Friday, February 7, 2014 at 3:21:36 PM UTC+6, jigs9...@gmail.com wrote:
>
>
> Hi Srivats,
>
> I just want to know how can we generate packets with MTU size
> greater than 1500 MTU usin Ostinato. I tried to generate packets
> with MTU greater than 1500 but packets are not getting generated. 
>
> And if I try to send packets with Greater MTU size using ping
> command, its working fine on the same system where Ostinato is
> installed. Below is the o/p using ping command.
>
> Sending Packets:
>
> *********************************************************************
>
> [root@kipgen01 ~]# ping -s 2000 172.29.7.48
> PING 172.29.7.48 (172.29.7.48) 2000(2028) bytes of data.

> 2008 bytes from 172.29.7.48 <http://172.29.7.48>: icmp_seq=1 ttl=62
> time=0.748 ms
> 2008 bytes from 172.29.7.48 <http://172.29.7.48>: icmp_seq=2 ttl=62
> time=0.499 ms
> 2008 bytes from 172.29.7.48 <http://172.29.7.48>: icmp_seq=3 ttl=62

> --
> Get Ostinato News and Updates on Twitter - Follow @ostinato
> (http://twitter.com/ostinato)
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