Re: [mpls] Poll 2: New SPL vs re-purposed ELI for carrying Network Action Indicators

Tony Li <tony.li@tony.li> Fri, 17 June 2022 13:45 UTC

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From: Tony Li <tony.li@tony.li>
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Date: Fri, 17 Jun 2022 06:45:39 -0700
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To: Robert Raszuk <rraszuk@gmail.com>
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Subject: Re: [mpls] Poll 2: New SPL vs re-purposed ELI for carrying Network Action Indicators
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Hi Robert,


> Can you please kindly explain why the proposed model is insufficient ? 8 bits of ELC seems more then enough to indicate presence of an ISD entry following EL entry. How you encode ISD itself is completely up to you. You could fill it up to the wire's MTU if deemed necessary. 


As I explained in my presentation in the last IETF, if you start expanding the ELI LSE’s, you run the risk of old implementations misinterpreting your ISD entries. It’s no longer backward compatible.


> I understand you are proposing to encode functions and actions immediately after the MNA indicator, but this is just a possibility - not sure WG agrees as the best one or clearly not a killer argument IMO. 


The alternatives are to shove it all to PSD or the control plane. Neither of those is compelling.


> Side note - IMHO pumping more bits into MPLS Label Stack is not a good thing. 


And adding complexity is not a good thing either, but people seem insistent.

Tony