Re: [spring] SRv6 Network Programming: ENH = 59

["Pablo Camarillo (pcamaril)" <[e-mail]>]

Hi Ron,

We use the next header value 59 to identify at the receiver that there is no other kind of Internet Protocol beneath to be processed. 
Note that we are *not* using 59 to identify the fact that it is an ethernet header (i.e. other non Internet-Protocols would also use the 59 to identify that no further IP header processing has to be performed). The SID identifies that an Ethernet header follows the IPv6 extension headers.

Thanks,
Pablo.

-----Original Message-----
From: ipv6 <[e-mail]> on behalf of Ron Bonica <rbonica=[e-mail]>
Date: Monday, 6 May 2019 at 02:48
To: SPRING WG <[e-mail]>, 6man WG <[e-mail]>
Subject: SRv6 Network Programming: ENH = 59

    Folks,
    
    According to Section 4.4 of draft-ietf-spring-srv6-network-programming-00, when processing the End.DX2 SID, the Next Header must be equal to 59. Otherwise, the packet will be dropped.
    
    In the words of the draft, "We conveniently reuse the next-header value 59 allocated to IPv6 No Next Header [RFC8200].  When the SID corresponds to function End.DX2 and the Next-Header value is 59, we know that an Ethernet frame is in the payload without any further header."
    
    According to Section 4.7 RFC 8200, " The value 59 in the Next Header field of an IPv6 header or any  extension header indicates that there is nothing following that header.  If the Payload Length field of the IPv6 header indicates the presence of octets past the end of a header whose Next Header field contains 59, those octets must be ignored and passed on unchanged if the packet is forwarded."
    
    Does the WG think that it is a good idea to reuse the Next Header value 59? Or would it be better to allocate a new Next Header value that represents Ethernet?
    
                                                              Ron
    
    
    Juniper Internal
    
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