Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]

Owen DeLong <owen@delong.com> Fri, 13 November 2015 20:44 UTC

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From: Owen DeLong <owen@delong.com>
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References: <8D175A1F-B1AE-44B4-838E-1C853B6C937D@cisco.com> <CAKD1Yr15C-uoxUw0kgWO-d=LmUK8qWGLS7vt+22W+k8xXtDY+g@mail.gmail.com> <2134F8430051B64F815C691A62D9831832F393F1@XCH-BLV-504.nw.nos.boeing.com> <2134F8430051B64F815C691A62D9831832F3941D@XCH-BLV-504.nw.nos.boeing.com> <563811DF.9020603@gmail.com> <2134F8430051B64F815C691A62D9831832F394F7@XCH-BLV-504.nw.nos.boeing.com> <563821EB.3040508@gmail.com> <2134F8430051B64F815C691A62D9831832F39A09@XCH-BLV-504.nw.nos.boeing.com> <56392B6D.8030703@gmail.com> <2134F8430051B64F815C691A62D9831832F3A88F@XCH-BLV-504.nw.nos.boeing.com> <2134F8430051B64F815C691A62D9831832F3A97F@XCH-BLV-504.nw.nos.boeing.com> <CAHDzDLBG8xZxUFsAuN-7WuruZcULF1QAS_ch=gD5rGQMZfskow@mail.gmail.com> <2134F8430051B64F815C691A62D9831832F3E8B0@XCH-BLV-504.nw.nos.boeing.com> <CAJE_bqd-1x5EJ=rkebiBFdNds6so5+iNGftiUf+MUu9P1up1bA@mail.gmail.com> <CAKD1Yr1X8UzQ58FeG6PYG9L1MyibV0J-JpcS2hxwzCdV=HizXg@mail.gmail.com> <ad0e90cf5f74407fa5338a7b6130bd1a@XCH-RTP-005.cisco.co! ! m> <5645DE07.3050605@gmail.com> <6f8ba1d9357b4cf786df990ebe09c965@XCH-RTP-005.cisco.com> <D76E6E81-419B-459D-AF5F-A6B8781CF445@delong.com> <a562066cf4d14f80aa94de314c27d632@XCH-RTP-005.cisco.com>
To: "Hemant Singh (shemant)" <shemant@cisco.com>
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Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
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> On Nov 13, 2015, at 11:36 , Hemant Singh (shemant) <shemant@cisco.com> wrote:
> 
> -----Original Message-----
> From: Owen DeLong [mailto:owen@delong.com] 
> Sent: Friday, November 13, 2015 12:43 PM
> To: Hemant Singh (shemant)
> Cc: Alexandre Petrescu; v6ops@ietf.org
> Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
> 
>> How is it possible to have a duplicate address on a loopback interface?
> 
> A router configures a loopback interface and provisions an IPv6 address on the interface.  The is a LAN in the router downstream port which the router destines packets to using the source as the IPv6 address on the loopback.  The LAN segment may have a duplicate unless the loopback IPv6 address is disjoint from any IPv6 prefix on the router and router LAN/WAN segment.   Another use case is already mentioned in this thread - two routers directly connected.
> 
> Hemant 

Sure, but in such a case, DAD on the LAN interface wouldn’t detect the loopback nor would DAD on the loopback interface.

Owen