Re: [ippm] [**EXTERNAL**] Re: AD review of draft-ietf-ippm-stamp

Henrik Nydell <> Mon, 19 August 2019 17:55 UTC

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From: Henrik Nydell <>
Date: Mon, 19 Aug 2019 19:55:40 +0200
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To: Rakesh Gandhi <>
Cc: Mirja Kuehlewind <>, "Civil, Ruth" <>, Greg Mirsky <>, "" <>, Shahram Davari <>, "" <>, IPPM Chairs <>, IETF IPPM WG <>, "" <>
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Subject: Re: [ippm] [**EXTERNAL**] Re: AD review of draft-ietf-ippm-stamp
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I think the Yang model should not put too many restrictions in place for
the port used for the TWAMP-test packets, neither source nor destination
ports. Although some ports are indeed assigned to specific services, the
idea of a test function often is to be able to as closely as possible mimic
the patterns of a real service.

Limiting the port at the application (TWAMP/STAMP) level would not be the
solution to "securing" an internet service, each application needs to have
enough protection to not become disturbed by unknown packets. As an
example, neither Chrome nor Edge prevents me from entering URLs with
destination TCP ports that are reserved for other protocols. I moved my
private web server to port 88 (which is assigned to Kerberos, although I am
not using Kerberos) and both browsers were fine with letting me point to

On Mon, Aug 19, 2019 at 6:38 PM Rakesh Gandhi <>

> Hi Mirja,
> Thanks for your comments, yes, such appropriate caveat can be added for
> the user port range in the TWAMP Yang mode.
> Thanks,
> Rakesh
> On Mon, Aug 19, 2019 at 11:25 AM Mirja Kuehlewind <>
> wrote:
>> Hi Rakesh,
>> Just quickly a comment on this bit:
>> > On 19. Aug 2019, at 17:12, Rakesh Gandhi <>
>> wrote:
>> >
>> > TWAMP Yang model [draft-ietf-ippm-twamp-yang-13] can also support the
>> range to allow user ports. An example caveat is specified in
>> [draft-ietf-tram-turnbis-29]
>> > as "unless the TURN server application knows, through some means not
>> >    specified here, that other applications running on the same host as
>> the TURN server application will not be impacted by allocating ports
>> outside this range. "
>> >
>> I don’t think it is the same thing for turn and stamp/twamp.
>> In turn you aim at actually opening a connection to a remote endpoint and
>> need to make sure that that endpoint is talking the same protocol as you
>> do. That remote endpoint might actually implement different services on
>> different ports.
>> TWAMP is used for testing, therefore it could make sense to set up a
>> testing server that listens on exactly the same port as your application
>> would usually do. Yes, when using twamp on such ports, you have to make
>> sure that your twamp server does not implement another protocol on that
>> port but often these server are decided for testing only and preconfigured
>> in a respective way.
>> Mirja


*Henrik Nydell*
*Sr Product Manager*
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