Re: [Isis-wg] [Technical Errata Reported] RFC5309 (5007)

Alexander -

I am not speaking for the RFC authors, but regarding your point:

> o	Are assigned with IP addresses and subnet masks yielding different
> subnets

I fail to see why this issue is unique to (or associated with) running in P2P mode. 

The unnumbered case is specifically mentioned because in such a case it can be expected that the next hop address will be a loopback address and therefore there will be no common subnet.
But in the numbered case whether you have one neighbor in P2P mode or many neighbors in multi-access mode the msimatched subnet issue is the same. Therefore I see no reason why these RFCs should discuss it.

???

   Les

> -----Original Message-----
> From: Isis-wg [mailto:isis-wg-bounces@ietf.org] On Behalf Of RFC Errata
> System
> Sent: Sunday, April 30, 2017 1:16 AM
> To: Naiming Shen (naiming); alex.zinin@alcatel-lucent.com;
> akatlas@gmail.com; db3546@att.com; Alvaro Retana (aretana);
> chopps@chopps.org; hannes@gredler.at
> Cc: Alexander.Vainshtein@ecitele.com; isis-wg@ietf.org; rfc-editor@rfc-
> editor.org
> Subject: [Isis-wg] [Technical Errata Reported] RFC5309 (5007)
> 
> The following errata report has been submitted for RFC5309, "Point-to-Point
> Operation over LAN in Link State Routing Protocols".
> 
> --------------------------------------
> You may review the report below and at:
> http://www.rfc-editor.org/errata_search.php?rfc=5309&eid=5007
> 
> --------------------------------------
> Type: Technical
> Reported by: Alexander Vainshtein <Alexander.Vainshtein@ecitele.com>
> 
> Section: 4.3
> 
> Original Text
> -------------
> For the ARP implementation (which checks that the subnet of the source
> address of the ARP request matches the local interface address), this check
> needs to be relaxed for the unnumbered p2p-over-lan circuits.
> 
> Corrected Text
> --------------
> For the ARP implementation (which checks that the subnet of the source
> address of the ARP request matches the local interface address), this check
> needs to be relaxed for the p2p-over-lan circuits (both numbered and
> unnumbered).
> 
> Notes
> -----
> Consider the following situation:
> 1.	Two routers, R1 and R2, are connected by a physical P2P  Ethernet
> link
> 2.	OSPFv2 is enabled on the interfaces representing the endpoints of
> this link.
> 3.      From the OSPF POV these interfaces:
> o	Are configured as P2P
> o	Belong to the same area
> o	Are assigned with IP addresses and subnet masks yielding different
> subnets
> 4.    ARP check mentioned in the problematic text is not relaxed.
> 
> Under this conditions:
> -Both R1 and R2 will accept Hello messages sent by the other router (becase
> it ignores subnet in Hello messages received via P2P interfaces)
> - Adjacency between R1 and R2 will progress to FULL state (because all
> OSPFv2 messages will be sent with AllSPFRouters multicast IPv4 address)
> - Unicast traffic sent by R1 to R2 (and vice versa) will be blackholed because
> ARP will not resolve addresses assigned to the corresponding interfaces.
> 
> Instructions:
> -------------
> This erratum is currently posted as "Reported". If necessary, please use
> "Reply All" to discuss whether it should be verified or rejected. When a
> decision is reached, the verifying party can log in to change the status and
> edit the report, if necessary.
> 
> --------------------------------------
> RFC5309 (draft-ietf-isis-igp-p2p-over-lan-06)
> --------------------------------------
> Title               : Point-to-Point Operation over LAN in Link State Routing
> Protocols
> Publication Date    : October 2008
> Author(s)           : N. Shen, Ed., A. Zinin, Ed.
> Category            : INFORMATIONAL
> Source              : IS-IS for IP Internets
> Area                : Routing
> Stream              : IETF
> Verifying Party     : IESG
> 
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