Re: [Detnet] Flow Identification in IPv6

Tom Herbert <tom@herbertland.com> Mon, 08 March 2021 16:32 UTC

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From: Tom Herbert <tom@herbertland.com>
Date: Mon, 8 Mar 2021 09:31:58 -0700
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To: "Yangfan (IP Standard)" <shirley.yangfan@huawei.com>
Cc: Greg Mirsky <gregimirsky@gmail.com>, "draft-geng-6man-redundancy-protection-srh@ietf.org" <draft-geng-6man-redundancy-protection-srh@ietf.org>, DetNet WG <detnet@ietf.org>, 6man WG <ipv6@ietf.org>
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Subject: Re: [Detnet] Flow Identification in IPv6
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On Mon, Mar 8, 2021 at 2:38 AM Yangfan (IP Standard)
<shirley.yangfan@huawei.com> wrote:
>
> Hi Greg,
>
>
>
> Literally speaking, IPv6  Flow Label could be used to identify a specific flow needing redundancy protection in SRv6 data plane. But I may have concerns that flow label cannot be protected to be unmodified en route. A modified flow label can be a disaster for the traffics  which are seeking for deterministic forwarding, not only this flow, also affecting other flows using redundancy protection. And with several security issues mentioned in RFC6437, I doubt if it is a good idea to user IPv6 Flow Label.
>
> Just my 2cents opinion, how do you and other people see it?
>

If this is to be used in a SRv6 domain which is itself a limited
domain, then I think the problems you mention aren't as much of a
concern since flow label would be used in a controlled environment.
The upside of using flow label is that it's already in the IPv6
header, it can be consumed by non-SRv6 devices, and putting the same
information in TLVs incurs the overhead and cost of processing TLVs in
the critical datapath.

Tom

>
>
> Regards,
>
> Fan
>
>
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> 发件人: Greg Mirsky [mailto:gregimirsky@gmail.com]
> 发送时间: 2021年3月7日 4:20
> 收件人: draft-geng-6man-redundancy-protection-srh@ietf.org
> 抄送: 6man WG <ipv6@ietf.org>rg>; DetNet WG <detnet@ietf.org>rg>; Greg Mirsky <gregory.mirsky@ztetx.com>
> 主题: Flow Identification in IPv6
>
>
>
> Dear Authors,
>
> thank you for bringing your proposal to the discussion. I agree with your view that the explicit routing enabled by SRv6 creates an environment where PREOF can be used. And, as we know, The PREOF may be used in a DetNet domain to lower packet loss ratio and provide bounded latency.
>
> After reading the draft, I've got a question for you. What do you see as the difference between the IPv6 Flow Label per RFC 6437 and the Flow Identification field in the TLV proposed in the draft? Could the IPv6 Flow Label be used to identify the flow for the PREOF?
>
>
>
> Regards,
>
> Greg
>
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