RE: CRH and RH0

[Ron Bonica <[e-mail]>]

Darren,

What updates do you suggest?

                         Ron




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From: Darren Dukes (ddukes) <[e-mail]>
Sent: Wednesday, May 13, 2020 1:16 PM
To: Ron Bonica <[e-mail]>
Cc: [e-mail]; 6man <[e-mail]>
Subject: Re: CRH and RH0

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Hi Ron,

I'm still trying to figure out where you're going with this.
First it was SRm6, then an RH0 replacement, then not an RH0 replacement (in the 6man meeting), then it sort of is...

So I'm hoping you'll update the draft so I can understand a bit more:
- CRH has nothing to do with RH0.
- CRH operates only within a limited domain.

Anything else to clarify from others comments would help too.

Thanks
  Darren

On May 12, 2020, at 5:36 PM, Ron Bonica <[e-mail]<mailto:[e-mail]>> wrote:

Ole, Darren,

The CRH is a general purpose Routing header that operates inside of a network domain. In the sense that it is a general purpose routing header, it replaces RH0. In the sense that it is restricted to a network domain, it does not replace RH0.

If adding these two sentences will cause you to support the draft, or at least not object to it, I will happily add them!

Are these the only objections?

                                                                                   Ron



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-----Original Message-----
From: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Sent: Tuesday, May 12, 2020 4:38 PM
To: Ron Bonica <[e-mail]<mailto:[e-mail]>>
Cc: Darren Dukes (ddukes) <[e-mail]<mailto:[e-mail]>>; 6man <[e-mail]<mailto:[e-mail]>>
Subject: Re: CRH and RH0

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Hi Ron,


The answer to your question is a bit nuanced. My goals were to build a general purpose routing header that overcomes the RH0's limitations. Those being:

     - Its size
     - Its security issues

Now, is that a replacement for RH0? In one way, yes. RH0 and CRH are both general purpose routing headers. In another sense, no. RH0 is meant to traverse network boundaries. But RFC 5095 taught us that letting routing header traverse network boundaries might not be a wonderful idea. So, CRH is restricted to a network domain.

If CRH could be a RH0 replacement, you would have to show how the tag distribution mechanism would work across the Internet?
RH0 was supported in every IPv6 node, given the requirement for a tag->IPv6 address (or is it forwarding method) mapping, I can't quite see how that would be done in a general enough fashion for CRH?

I don't think RFC5095 taught us that source routing cannot be done across the Internet.
In fact I don't see how the CRH draft prevents the RFC5095 attack to happen inside of the CRH limited domain.
Just send a packet with a list of tag#0, tag#1, tag#0, tag#1 and you have the same amplification attack.

And now I return to my original question. When engineering students read the CRH RFC in 25 years, will they really care what my motivation was? Why should we burden them with this detail?

To the contrary. Take the motivations and intentions behind IPv6. We have spent thousands of emails trying to decode what the original intensions with EHs and their limitations were, why the minimum MTU was 1280, recently I saw a thread about the reasons for why TTL/HL and protocol/next header was swapped between v4 and v6. If your protocol is successful, the original napkin it was designed on will become legend. ;-)

Best regards,
Ole