On Thu, Apr 9, 2015 at 1:50 PM, Erik Nordmark <[email protected]> wrote:
> On 4/8/15 7:20 PM, Xuxiaohu wrote: > >> Hi Erik, >> >> But I couldn't tell from the emails on the BIER list whether the >>> constraints on the first nibble value is a strict requirement in all cases, >>> or whether it is conditional on something (and if so, what is the >>> condition). >>> >> The conditions that I have thought of include: 1) the encapsulation is >> sensitive to packet misordering; 2) the encapsulation may be transported >> over an MPLS PSN; 3) LSRs within that MPLS PSN may use the contents of the >> MPLS payload to select the ECMP path. >> > Those are conditions when the misordering would happen. But are you saying > that any LSR is free to use the MPLS payload (including looking for 4 and 6 > in the first nibble) to determine whether the packet is IPv4 and IPv6 and > use what it thinks are IPv4 and IPv6 fields for ECMP purposes? Take a quick look at RFC 4385 - which is the control word for pseudo-wires. The short form is that a number of routers at the time peeked beneath the label stack to figure out whether what was inside as IPv4 or IPv6 based solely upon the first nibble. A recommendation was made that the checksum should also be verified, but the only equipment that I'm certain of that did that isn't around anymore. Also look at Section 2.4 of RFC 7325. Alia > > Thanks, > Erik > > >> Best regards, >> Xiaohu >> >> Once I know that answer we can definitely add some text pointing out the >>> issue. >>> >>> Thanks, >>> Erik >>> >>> Best regards, >>>> Xiaohu >>>> >>>> -----Original Message----- >>>>> From: Erik Nordmark [mailto:[email protected]] >>>>> Sent: 2015年3月26日 5:01 >>>>> To: [email protected] >>>>> Subject: [nvo3] Encapsulation considerations >>>>> >>>>> >>>>> I presented part of this at the most recent NVO3 interim meeting.The >>>>> full >>>>> >>>> 12 >>>> >>>>> areas of considerations where presented at RTGWG earlier this week. >>>>> The draft is >>>>> http://datatracker.ietf.org/doc/draft-rtg-dt-encap/ >>>>> and the slides are at >>>>> http://www.ietf.org/proceedings/92/slides/slides-92-rtgwg-8.pdf >>>>> >>>>> There is probably additional things in there to consider for NVO3, >>>>> and >>>>> >>>> advice >>>> >>>>> that can be reused to make it easier to move NVO3 forward. >>>>> >>>>> Regards, >>>>> Erik >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>> nvo3 mailing list >>>> [email protected] >>>> https://www.ietf.org/mailman/listinfo/nvo3 >>>> >>>> >> > _______________________________________________ > sfc mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/sfc >
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