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From: Yasuhiro Ohara (yasu_at_SFC.WIDE.AD.JP)
Date: Wed Dec 11 2002 - 20:17:36 CST
From: "Manral, Vishwas" <VishwasMNETPLANE.COM>
Subject: Re: How could OPSFv3 support IPv4 ?
Date: Wed, 11 Dec 2002 11:31:48 -0500
> Hi Yasu,
> I think you missed "Link-LSA" equivalents. I think they would be required
> too !!!
> -----Original Message-----
> From: Yasuhiro Ohara [mailto:yasuSFC.WIDE.AD.JP]
> Sent: Wednesday, December 11, 2002 7:48 PM
> To: OSPFDISCUSS.MICROSOFT.COM
> Subject: Re: How could OPSFv3 support IPv4 ?
> > I am wondering how OSPFv3 could support IPv4.
> > According to the RFC2740, the 24-bit OSPFv3 options field describes the
> > router capabilities. For example, the R-bit and the V6-bit are used in
> > order to announce IPv6 forwarding capabilities. However, what's happened
> > if this V6-bit is clear ?
> RFC2740's section 2.7 gives the exact answer:
> V6-bit specializes the R-bit; if the V6-bit is clear an OSPF
> speaker can participate in OSPF topology distribution without
> being used to forward IPv6 datagrams. If the R-bit is set and the
> V6-bit is clear, IPv6 datagrams are not forwarded but diagrams
> belonging to another protocol family may be forwarded.
> In routers do not support other protocol family other than IPv6,
> the router having V6-bit off should be treated as a non-working router
> from the rest of the network.
> > If there would be a V4-bit in order to announce the IPv4 capabilities,
> > how could OSPFv3 be extended in order to support IPv4 like Integrated
> > ISIS ?
> You'll need only to define IPv4 version of Intra-Area-Prefix-LSA,
> Inter-Area-Prefix-LSA, AS-External-LSA. Using IPv6 address holding
> embedded IPv4 address is another option. I guess IPv4-mapped will be
> the right choice semantically in that case, but it may not be
> accepted as I saw someone states "IPv4-mapped address should not
> appear on the wire" somewhere. I believe it means as IP source or
> destination, though.