Re: [bess] [Softwires] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549
Xiejingrong <xiejingrong@huawei.com> Wed, 26 June 2019 11:39 UTC
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From: Xiejingrong <xiejingrong@huawei.com>
To: "ian.farrer@telekom.de" <ian.farrer@telekom.de>, Zhuangshunwan <zhuangshunwan@huawei.com>, "ianfarrer@gmx.com" <ianfarrer@gmx.com>
CC: "softwires@ietf.org" <softwires@ietf.org>, "bess@ietf.org" <bess@ietf.org>, "idr@ietf.org" <idr@ietf.org>
Thread-Topic: [Softwires] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549
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Subject: Re: [bess] [Softwires] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549
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Hi folks, I guess this is an inconsistency due to past carelessness. Is there anyone can tell us the history of this inconsistency ? RFC4364(VPNv4 over IPv4 network) and RFC4659(VPNv6 over IPv4 or IPv6 network) both require to use RD+IP(v4 or v6 respectively) as nexthop. RFC5549(VPNv4/IPv4 over IPv6 network) requires to use IPv6 without RD as nexthop. This same question also occur in MVPN: RFC6515, which talks about MVPN6 over IPv4/IPv6, or MVPN over IPv6, but does imply loosely to use IPv4/IPv6 without RD as nexthop (see below). The purpose of this document is to make clear that whenever a PE address occurs in an MCAST-VPN route (whether in the NLRI or in an attribute), the IP address family of that address is determined by the length of the address (a length of 4 octets for IPv4 addresses, a length of 16 octets for IPv6 addresses), NOT by the AFI field of the route. My suggestion: implementation should interpret nexthop RD+IPv4 and nexthop IPv4 the same, and interpret nexthop RD+IPv6 and nexthop IPv6 the same. The RFC5549/SRv6-VPN/RFC6515 can keep as current shape, while interoperate can meet between different implementations. Need a new draft to clarify this and to give a guide on further FooService over FooNetwork ? Thanks Jingrong From: Softwires [mailto:softwires-bounces@ietf.org] On Behalf Of ian.farrer@telekom.de Sent: Tuesday, June 25, 2019 11:12 PM To: Zhuangshunwan <zhuangshunwan@huawei.com>; ianfarrer@gmx.com Cc: softwires@ietf.org; bess@ietf.org Subject: Re: [Softwires] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549 Hi Shunwan, I’ve just re-checked RFC5539, and the referenced section 3 of RFC2545 and I can find nothing about using VPN-IPv6 for encoding the next-hop. Section 3 of RFC5539 is very clear that it’s a 16-byte GU IPv6 address or 32-bytes with a GU and LL address. Can you point me to the text that gives you the impression that VPN-IPv6 is correct? Note – I see that there is reported Errata on RFC5549, (not verified) saying that the length should be 24 or 48 to include the RD. However, as mentioned above, the supporting text in multiple places in the RFC and its references support the use of an IPv6 address (or 2) with no RD at 16 or 32 bytes, so this does seem to be the intention of the document as written. https://www.rfc-editor.org/errata_search.php?rfc=5549 Thanks, Ian From: Softwires <softwires-bounces@ietf.org<mailto:softwires-bounces@ietf.org>> on behalf of Zhuangshunwan <zhuangshunwan@huawei.com<mailto:zhuangshunwan@huawei.com>> Date: Tuesday, 25. June 2019 at 13:18 To: "ianfarrer@gmx.com<mailto:ianfarrer@gmx.com>" <ianfarrer@gmx.com<mailto:ianfarrer@gmx.com>> Cc: "softwires@ietf.org<mailto:softwires@ietf.org>" <softwires@ietf.org<mailto:softwires@ietf.org>>, "bess@ietf.org<mailto:bess@ietf.org>" <bess@ietf.org<mailto:bess@ietf.org>> Subject: Re: [Softwires] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549 Hi Ian, Thanks for your response! The opinion I have collected is: Per RFC4634, the IPv4-VPN routes shall carry the V4 Next-hop, beginning with an 8-octet RD and ending with a 4-octet IPv4 address. Per RFC4659, the IPv6-VPN routes shall carry the V6 Next-hop, beginning with an 8-octet RD and ending with a 16-octet IPv6 address. When we start to implement the IPv4 VPN over IPv6 Core, it is a natural way to encode the IPv4-VPN routes with VPN-IPv6 next-hop (i.e. beginning with an 8-octet RD and ending with a 16-octet IPv6 address) . I believe this is not just a minority opinion, and some of the current implementations are also doing this way. I hope that the WGs can give a consistent opinion on this issue and avoid interoperability problem in the future. Thanks, Shunwan From: ianfarrer@gmx.com<mailto:ianfarrer@gmx.com> [mailto:ianfarrer@gmx.com] Sent: Monday, June 24, 2019 8:08 PM To: Zhuangshunwan <zhuangshunwan@huawei.com<mailto:zhuangshunwan@huawei.com>> Cc: bess@ietf.org<mailto:bess@ietf.org>; softwires@ietf.org<mailto:softwires@ietf.org> Subject: Re: [Softwires] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549 Hi, My reading of Section 3 of RFC5549 is that the v6 next-hop is encoded as an IPv6 address: The BGP speaker receiving the advertisement MUST use the Length of Next Hop Address field to determine which network-layer protocol the next hop address belongs to. When the Length of Next Hop Address field is equal to 16 or 32, the next hop address is of type IPv6. It’s also worth noting that RFC4659 Section 2 states: A VPN-IPv6 address is a 24-octet quantity, beginning with an 8-octet "Route Distinguisher" (RD) and ending with a 16-octet IPv6 address. So, not 16 or 32 bytes. Thanks, Ian On 22. Jun 2019, at 09:59, Zhuangshunwan <zhuangshunwan@huawei.com<mailto:zhuangshunwan@huawei.com>> wrote: Dear authors and WGs, RFC5549 Section 6.2 says: . 6.2. IPv4 VPN over IPv6 Core . . The extensions defined in this document may be used for support of . IPV4 VPNs over an IPv6 backbone. In this application, PE routers . would advertise VPN-IPv4 NLRI in the MP_REACH_NLRI along with an IPv6 . Next Hop. . . The MP_REACH_NLRI is encoded with: . . o AFI = 1 . . o SAFI = 128 . . o Length of Next Hop Network Address = 16 (or 32) . . o Network Address of Next Hop = IPv6 address of Next Hop . . o NLRI = IPv4-VPN routes Regarding IPv4-VPN routes, RFC4634 Section 4.3.2 says: . 4.3.2. Route Distribution Among PEs by BGP [snip] . When a PE router distributes a VPN-IPv4 route via BGP, it uses its . own address as the "BGP next hop". This address is encoded as a . VPN-IPv4 address with an RD of 0. ([BGP-MP] requires that the next . hop address be in the same address family as the Network Layer . Reachability Information (NLRI).) It also assigns and distributes an . MPLS label. (Essentially, PE routers distribute not VPN-IPv4 routes, . but Labeled VPN-IPv4 routes. Cf. [MPLS-BGP].) When the PE processes . a received packet that has this label at the top of the stack, the PE . will pop the stack, and process the packet appropriately. [snip] Question: RFC5549 defines "IPv4 VPN over IPv6 Core", When a PE router distributes a VPN-IPv4 route with an IPv6 Next-Hop via BGP, should the IPv6 Next-Hop be encoded as an VPN-IPv6 address with an RD of 0 ? Thanks, Shunwan _______________________________________________ Softwires mailing list Softwires@ietf.org<mailto:Softwires@ietf.org> https://www.ietf.org/mailman/listinfo/softwires
- [bess] Regarding the Next Hop Network Address cod… Zhuangshunwan
- Re: [bess] [Softwires] Regarding the Next Hop Net… ianfarrer
- Re: [bess] [Softwires] Regarding the Next Hop Net… Zhuangshunwan
- Re: [bess] [Softwires] Regarding the Next Hop Net… ian.farrer
- Re: [bess] [Softwires] Regarding the Next Hop Net… Xiejingrong
- Re: [bess] [Softwires] Regarding the Next Hop Net… Robert Raszuk
- Re: [bess] [Idr] [Softwires] Regarding the Next H… UTTARO, JAMES
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Alexander Okonnikov
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Robert Raszuk
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Robert Raszuk
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Alexander Okonnikov
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Xiejingrong
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Vigoureux, Martin (Nokia - FR/Paris-Saclay)
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Robert Raszuk
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Xiejingrong
- Re: [bess] [Softwires] [Idr] Regarding the Next H… Rajiv Asati (rajiva)
- Re: [bess] [Softwires] [Idr] Regarding the Next H… Zhuangshunwan
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Xiejingrong
- Re: [bess] [Softwires] [Idr] Regarding the Next H… Robert Raszuk
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Zhuangshunwan
- Re: [bess] [Softwires] [Idr] Regarding the Next H… ian.farrer
- Re: [bess] [Idr] [Softwires] Regarding the Next H… stephane.litkowski
- Re: [bess] [Softwires] [Idr] Regarding the Next H… stephane.litkowski
- Re: [bess] [Idr] [Softwires] Regarding the Next H… Robert Raszuk
- Re: [bess] [Idr] [Softwires] Regarding the Next H… stephane.litkowski