Re: [lisp] Confirm/Deny changes on draft 6830bis

[Fabio Maino <[e-mail]>]

On 1/12/18 8:20 AM, Albert Cabellos wrote:
> Hi all
>
> As editor of 6830bis I´d like to confirm or deny the following changes 
> which I believe have support.
>
> Please note that I have intentionally ignored minor/editorial changes 
> to help sync all the participants. I hope that the list below captures 
> the most relevant ones.
>
> Also note that I don´t necessarily agree with all the changes listed 
> below, but that´s an opinion with a different hat.
>
> WG: Please CONFIRM or DENY:
>
> -------
>
> A.- Remove definitions of PA and PI
confirm.

I think one of the goals of the charter was to to open up to a broad set 
of use cases where that terminology might not be meaningful.

>
> B.- Change definitions of EID and RLOC as ‘identifier of the overlay’ 
> and ‘identifier of the underlay’ respectively.

personally, I'm not keen to this change of terminology.

EID and RLOC have become of common use, and well understood, even 
outside of the LISP circles. I've often assisted to conversations in 
non-LISP groups where people use the term LISP EID/RLOC to qualify IP 
addresses in the overlay/underlay.


>
> C.- In section 5.3, change the description of the encap/decap 
> operation concerning how to deal with ECN and DSCP bits to (new text 
> needs to be validated by experts):
>
>     When doing ITR/PITR encapsulation:
>
>     o  The outer-header 'Time to Live' field (or 'Hop Limit' field, in
>     the case of IPv6) SHOULD be copied from the inner-header 'Time to
>     Live' field.
>
>     o  The outer-header 'Differentiated Services Code Point' (DSCP)
>     field (or the 'Traffic Class' field, in the case of IPv6) SHOULD
>     be copied from the inner-header DSCP field ('Traffic Class' field,
>     in the case of IPv6) considering the exception listed below.
>
>     o  The 'Explicit Congestion Notification' (ECN) field (bits 6 and
>     7 of the IPv6 'Traffic Class' field) requires special treatment in
>     order to avoid discarding indications of congestion [RFC3168]. ITR
>     encapsulation MUST copy the 2-bit 'ECN' field from the inner
>     header to the outer header. Re-encapsulation MUST copy the 2-bit
>     'ECN' field from the stripped outer header to the new outer header.
>
>     When doing ETR/PETR decapsulation:
>
>      o  The inner-header 'Time to Live' field (or 'Hop Limit' field,
>     in the case of IPv6) SHOULD be copied from the outer-header 'Time
>     to Live' field, when the Time to Live value of the outer header is
>     less than the Time to Live value of the inner header.  Failing to
>     perform this check can cause the Time to Live of the inner header
>     to increment across encapsulation/decapsulation cycles.  This
>     check is also performed when doing initial encapsulation, when a
>     packet comes to an ITR or PITR destined for a LISP site.
>
>     o  The inner-header 'Differentiated Services Code Point' (DSCP)
>     field (or the 'Traffic Class' field, in the case of IPv6) SHOULD
>     be copied from the outer-header DSCP field ('Traffic Class' field,
>     in the case of IPv6) considering the exception listed below.
>
>     o  The 'Explicit Congestion Notification' (ECN) field (bits 6 and
>     7 of the IPv6 'Traffic Class' field) requires special treatment in
>     order to avoid discarding indications of congestion [RFC3168]. If
>     the 'ECN' field contains a congestion indication codepoint (the
>     value is '11', the Congestion Experienced (CE) codepoint), then
>     ETR decapsulation MUST copy the 2-bit 'ECN' field from the
>     stripped outer header to the surviving inner header that is used
>     to forward the packet beyond the ETR.  These requirements preserve
>     CE indications when a packet that uses ECN traverses a LISP tunnel
>     and becomes marked with a CE indication due to congestion between
>     the tunnel endpoints.
>
>     Note that if an ETR/PETR is also an ITR/PITR and chooses to
>     re-encapsulate after decapsulating, the net effect of this is that
>     the new outer header will carry the same Time to Live as the old
>     outer header minus 1.
>
>     Copying the Time to Live (TTL) serves two purposes: first, it
>     preserves the distance the host intended the packet to travel;
>     second, and more importantly, it provides for suppression of
>     looping packets in the event there is a loop of concatenated
>     tunnels due to misconfiguration.  See Section 18.3 for TTL
>     exception handling for traceroute packets.
>
>
Confirm.


> D.- Simplify section ‘Router Locator Selection’ stating that the 
> data-plane MUST follow what´s stored in the map-cache (priorities and 
> weights), the remaining text should go to an OAM document.
Confirm on the section semplification.

Wrt putting the rest in a separate OAM document, I don't have a strong 
opinion. Probably not having a new document requires less work to be 
done that makes me lean toward NOT having a new OAM document.

>
> E.- Rewrite Section “Routing Locator Reachability” considering the 
> following changes:
>
>     *    Keep bullet point 1 (examine LSB), 6 (receiving a
>     data-packet) and Echo-Nonce
>     *    Move to 6833bis bullet point 2 (ICMP Network/Host
>     Unreachable),3 (hints from BGP),4 (ICMP Port Unreachable),5
>     (receive a Map-Reply as a response) and RLOC probing
>
>

Confirm.

>
> F.- Move Solicit-Map-Request to 6833bis

Confirm.
>
> G.- Move sections 16 (Mobility Considerations), 17 (xTR Placement 
> Considerations), 18 (Traceroute Consideration) to a new OAM document
>

I'm fine with both options. Probably not having a new document requires 
less work to be done that makes me lean toward NOT having a new OAM 
document.


Thanks,
Fabio

>
>
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