Hi Stewart,

I followed the ISO 8473 specification and find that a “flexible address 
structure” is similar to it.

ISO 8473 has a variable address length with a <len> field, while for the 
flexibility described in the “flexible address structure” draft, the 
flexibility refer to both a) variable length; 2) new semantics. ISO 8473 do 
cover the variable length, but semantics is not mentioned in it. So a new 
semantics carried address could be a main difference compared to ISO 8473.

Thanks,
Yihao

发件人: Stewart Bryant [mailto:[email protected]]
发送时间: 2021年2月3日 20:50
收件人: [email protected]; 
[email protected]; [email protected]; int-area 
<[email protected]>
抄送: Stewart Bryant <[email protected]>
主题: Using ISO8473 as a network layer to carry flexible addresses

Re drafts:


https://datatracker.ietf.org/doc/draft-jia-scenarios-flexible-address-structure/<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-jia-scenarios-flexible-address-structure%2F&data=04%7C01%7Ckiranm%40futurewei.com%7C95b5d102feaf4674ab8408d8c7972448%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637478799262464227%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=yDi0mFnbU60nFC5PJC%2BAAWVIdSMT%2FY8UO0XIiK3J4iI%3D&reserved=0>

https://datatracker.ietf.org/doc/draft-jia-flex-ip-address-structure/<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-jia-flex-ip-address-structure%2F&data=04%7C01%7Ckiranm%40futurewei.com%7C95b5d102feaf4674ab8408d8c7972448%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637478799262464227%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=XB9VFEQiaa0ZMjG5BuF%2FPeQnvFcmGgfY0%2Bye4s7CSoA%3D&reserved=0>

Since the authors are interested in network layer protocols that support 
multiple address types and multiple address lengths, I wonder if they have 
considered using ISO8473 as the bearer and developing that to their needs?

ISO 8473 is also known as ITU X233 (it costs money to download from ISO, but 
seems to be free from the ITU-T site). It is an in force and actually well 
deployed network layer protocol with many similar characteristics to IPv6. The 
reason that it is deployed is that it is used to support SS7. It also has a 
very widely deployed link-state IGP since IS-IS was developed to support 
ISO8474 and later adapted to support IP late run its life.

It was one of the contenders for IPv4 replacement, and so there RFCs that 
authors may study: RFC994 is a copy of the late version of the spec in RFC 
format. Then there is RFC1195 where Ross Callon shows how it works in an IETF 
environment carrying IETF transport protocols and this eventually became 
RFC1347 (TUBA), which whilst whilst marked Historic in the IETF RFC collection 
is almost certainly still implementable since the base network layer protocol 
is still an active standard.

It would need some work to determine the applicability of the protocol to your 
application and the feasibility of adding the necessary new address types (due 
to crowding of the existing address registry) and any other extensions that you 
might need.

Note BTW that it supports source routing functionality and so ought to be 
usable in an SR environment should that be needed.

There would also need to be work to see how feasible it would be to implement 
in a modern NPU, though having implemented it in a hardware assisted microcode 
platform that is quite similar to a modern NPU back in the 90s and having got 
quite creditable performance I think it is feasible to run this on modern 
hardware including repurposing the existing longest match engine to look up a 
number of your new address formats.

There are a bunch of specs here for your convenience although I have not 
studied the list in detail

http://www.networksorcery.com/enp/protocol/clnp.htm

Best regards

Stewart







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