RFC 5747
4over6 Transit Solution Using IP Encapsulation and MP-BGP Extensions
RFC 5747: 4over6 Transit Solution Using IP Encapsulation and MP-BGP Extensions 🦋✨
okay bestie, this one is a whole vibe 💖 RFC 5747 was written by J. Wu, Y. Cui, X. Li, and M. Xu from Tsinghua University, plus C. Metz from Cisco Systems, Inc. It came out in March 2010 as an Independent Submission and is marked Experimental 🧪. It's part of the RFC series with ISSN 2070-1721. Not a standards-track thing, just a "let's try it and see" kind of doc 🌈
Abstract 🌸
okay so IPv6 networks are getting deployed more and more, and that means there are going to be situations where people still need to reach IPv4 networks across IPv6 transit backbones 🫶 This doc describes a way to automatically discover and set up IPv4-over-IPv6 tunnels using extensions to multiprotocol BGP. The goal is to connect little islands of IPv4 networks across an IPv6-only backbone without anyone having to hand-configure a whole overlay of tunnels 😭✨ The stuff in here has been implemented, tested, and deployed on the large research IPv6 network in China 🇨🇳 it's giving proof-of-concept but make it real 💅
Status of This Memo 📜
not gonna lie, this section is a bit formal, but here's the tea: this is not an Internet Standards Track spec. It's published so people can look at it, try implementing it, and evaluate it 🧪
It defines an Experimental Protocol for the Internet community. It's a contribution to the RFC Series, independent of any other RFC stream 🍓 The RFC Editor chose to publish it at their discretion and makes no statement about whether it's good to implement or deploy. Docs approved for publication by the RFC Editor are not candidates for any level of Internet Standard. (For that bit, check Section 2 of RFC 5741 🙈)
If you want the current status, any errata, or a way to send feedback, go to:
http://www.rfc-editor.org/info/rfc5747
IESG Note 🎀
the IESG basically wanted to say that the mechanisms here are related to specs the IETF softwire working group developed and published as Standards Track documents. But the relationship doesn't stop this doc from being published, so it's all good 🫶
Copyright Notice 💜
Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. 📝
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication. Please read these carefully, because they spell out your rights and restrictions with respect to this document 👀
Table of Contents 🗂️
1. Introduction ....................................................3
2. 4over6 Framework Overview .......................................3
3. Prototype Implementation ........................................5
3.1. 4over6 Packet Forwarding ...................................5
3.2. Encapsulation Table ........................................6
3.3. MP-BGP 4over6 Protocol Extensions ..........................7
3.3.1. Receiving Routing Information from Local CE .........8
3.3.2. Receiving 4over6 Routing Information from a
Remote 4over6 PE ....................................8
4. 4over6 Deployment Experience ....................................9
4.1. CNGI-CERNET2 ...............................................9
4.2. 4over6 Testbed on the CNGI-CERNET2 IPv6 Network ............9
4.3. Deployment Experiences ....................................10
5. Ongoing Experiment .............................................11
6. Relationship to Softwire Mesh Effort ...........................12
7. IANA Considerations ............................................12
8. Security Considerations ........................................13
9. Conclusion .....................................................13
10. Acknowledgements ..............................................13
11. Normative References ..........................................141. Introduction 🌍✨
okay so IPv4 address space is basically gone, which is why more and more IPv6 networks are showing up, not just at the edges but on the backbone too 🌐 The catch is that there are still tons of legacy IPv4 hosts and apps out there. So IPv6 and IPv4 are going to have to coexist for a long time 😭
This means IPv6 networks will keep running into situations where they need to connect to IPv4 networks. Some IPv6 backbones will need to offer transit to IPv4 access networks attached to them. The way to do that is to encapsulate the IPv4 payloads and carry them inside IPv6 tunnels that span the backbone 🦋 There are some IPv6/IPv4 tunneling protocols and mechanisms out there already, but when this mechanism was introduced, most of them were about IPv6 over IPv4, not IPv4 over IPv6 🙈 Plain encapsulation methods, like the ones in [RFC2473], need manual configuration before they work. And when you need a lot of tunnels, manual config gets burdensome fast 😩 So this doc describes an approach called "4over6" 💖
The 4over6 mechanism has two parts: the control plane and the data plane 🧠 The control plane has to figure out how to set up an IPv4-over-IPv6 tunnel automatically and at scale, between a large number of edge routers. This doc describes experimental extensions to Multiprotocol Extensions for BGP (MP-BGP) [RFC4271] [RFC4760] that communicate tunnel endpoint info and establish 4over6 tunnels between dual-stack Provider Edge (PE) routers sitting at the edge of the IPv6 backbone 🛣️ Once the 4over6 tunnel is up, the data plane handles the packet forwarding stuff, meaning encapsulation and decapsulation 📦
2. 4over6 Framework Overview 🗺️
picture this: a bunch of IPv6-only P routers make up a native IPv6 backbone 🦴 The PE routers are dual-stack and called 4over6 PE routers. The IPv6 backbone works as a transit core that carries IPv4 packets across it. So each IPv4 access island can talk to the others through 4over6 tunnels running over that IPv6 transit core 💅
_._._._._ _._._._._
| IPv4 | | IPv4 |
| access | | access |
| island | | island |
_._._._._ _._._._._
| |
Dual-Stack Dual-Stack
"4over6 PE" "4over6 PE"
| |
| |
__+____________________+__
4over6 / : : : : \ IPv6 only
Tunnels | : : : : | transit core
between | : [P] : | with multiple
PEs | : : : : | [P routers]
| : : : : |
\_._._._._._._._._._._._._./
| / \ |
| |
Dual-Stack Dual-Stack
"4over6 PE" "4over6 PE"
| | |
_._._._._ _._._._._
| IPv4 | | IPv4 |
| access | | access |
| island | | island |
_._._._._ _._._._._
Figure 1: IPv4 over IPv6 Network Topologyso in Figure 1 there are several dual-stack PE routers hooked up to the IPv6 transit core 🎀 For the ingress 4over6 PE router to forward an IPv4 packet across the IPv6 backbone to the right egress 4over6 PE router, the ingress one has to know which IPv4 destination prefixes are reachable through each egress 4over6 PE router 🧭 MP-BGP gets extended to distribute that destination IPv4 prefix info between peering dual-stack PE routers. Section 4 of this document defines the 4over6 protocol field in MP-BGP, and Section 5 explains how MP-BGP's extended behavior supports this 🔥
Once the ingress 4over6 PE router learns the correct egress 4over6 PE router through MP-BGP, it forwards the packet across the IPv6 backbone using IP encapsulation 🎁 The egress 4over6 PE router receives the encapsulated packet, removes the IPv6 header, and forwards the original IPv4 packet on to its final IPv4 destination 🏁 Section 6 describes the packet forwarding procedure.
3. Prototype Implementation 🛠️
okay so the 4over6 mechanisms in this doc were actually built, tested, and deployed on Linux with kernel version 2.4 🐧 The prototype has three components: packet forwarding, the encapsulation table, and the MP-BGP extensions. The packet forwarding and encapsulation table are Linux kernel modules, and the MP-BGP extension was made by extending the Zebra routing software 💜
The following sections dig into each of these parts in detail ✨
3.1. 4over6 Packet Forwarding ✨
okay so forwarding an IPv4 packet through the IPv6 transit core has three parts 💅: encapsulating the incoming IPv4 packet with the IPv6 tunnel header, sending that encapsulated packet across the IPv6 transit backbone, and then decapsulating the IPv6 header and forwarding the original IPv4 packet. the backbone just uses native IPv6 routing and forwarding, because the P routers treat 4over6 tunneled packets as plain native IPv6 packets 🦋. so 4over6 packet forwarding only involves encapsulation and decapsulation, and both of those happen on the 4over6 PE routers. ngl the core doesn't even have to know it's tunneling 😭
Tunnel from Ingress PE to Egress PE
---------------------------->
Tunnel Tunnel
Entry-Point Exit-Point
Node Node
+-+ IPv4 +--+ IPv6 Transit Core +--+ IPv4 +-+
|S|-->--//-->--|PE|=====>=====//=====>=====|PE|-->--//-->--|D|
+-+ +--+ +--+ +-+
Original Ingress PE Egress PE Original
Packet (Encapsulation) (Decapsulation) Packet
Source Destination
Node NodeFigure 2: Packet Forwarding along 4over6 Tunnel
as shown in Figure 2, packet encapsulation and decapsulation both happen on the dual-stack 4over6 PE routers 🌸. Figure 3 shows the format of packet encapsulation and decapsulation, and it's the glow-up moment where the IPv4 packet gets wrapped up in IPv6 🎀.
+----------------------------------//-----+
| IPv4 Header | Packet Payload |
+----------------------------------//-----+
< Original IPv4 Packet >
|
|(Encapsulation on ingress PE)
|
v
< Tunnel IPv6 Headers > < Original IPv4 Packet >
+-----------+ - - - - - +-------------+-----------//--------------+
| IPv6 | IPv6 | IPv4 | |
| | Extension | | Packet Payload |
| Header | Headers | Header | |
+-----------+ - - - - - +-------------+-----------//--------------+
< Tunnel IPv6 Packet >
|
|(Decapsulation on egress PE)
|
v
+----------------------------------//-----+
| IPv4 Header | Packet Payload |
+----------------------------------//-----+
< Original IPv4 Packet >Figure 3: Packet Encapsulation and Decapsulation on Dual-Stack 4over6 PE Router
the encapsulation format to apply is IPv4 encapsulated in IPv6, as outlined in [RFC2473] 💜.
3.2. Encapsulation Table 🎀
okay this table is the MVP 👑. each 4over6 PE router keeps an encapsulation table (see Figure 4 below). every entry is an IPv4 prefix paired with its matching IPv6 address. the IPv4 prefix is a particular network sitting in an IPv4 access island network, and the IPv6 address is the 4over6 virtual interface (VIF) address of the PE router that prefix can be reached through. the table gets built and maintained from local configuration plus MP-BGP advertisements coming in from remote 4over6 PE routers 🧚.
+-------------+------------------------------------------------+
| IPv4 Prefix | IPv6 Advertising Address Family Border Router |
+-------------+------------------------------------------------+Figure 4: Encapsulation Table
the 4over6 VIF is an IPv6 /128 address that's locally configured on each 4over6 router 🦋. as an ordinary global IPv6 address, it also has to get injected into the IPv6 IGP so it can be reached across the IPv6 backbone. it's giving reachability and it's giving teamwork 🫶.
when an IPv4 packet shows up at the ingress 4over6 PE router, a lookup in the local IPv4 routing table gives you a pointer to the local encapsulation table entry with the matching destination IPv4 prefix 👀. there's a corresponding IPv6 address sitting in that entry. then the IPv4 packet gets encapsulated in an IPv6 header. the source address in that IPv6 header is the IPv6 VIF address of the local 4over6 PE router, and the destination address is the IPv6 VIF address of the remote 4over6 PE router stored in the local encapsulation table. after that, the packet goes through normal IPv6 forwarding for transport across the IPv6 backbone 💖.
when the encapsulated packet reaches the egress 4over6 PE router, the IPv6 header gets removed and the original IPv4 packet is forwarded to the destination IPv4 network, based on the outcome of the lookup in the IPv4 routing table on that egress 4over6 PE router ✨.
3.3. MP-BGP 4over6 Protocol Extensions 🌈
each 4over6 PE router has an IPv4 interface connected to one or more IPv4 access networks. it can peer with other IPv4 routers using IGP or BGP routing protocols to swap local IPv4 routing info. routing info can also get installed on the 4over6 PE router through static configuration methods 🍓.
each 4over6 PE also has at least one IPv6 interface to plug it into the IPv6 transit backbone. the 4over6 PE typically uses IGP routing protocols to exchange IPv6 backbone routing info with other IPv6 P routers. on top of that, the 4over6 PE router forms an MP-iBGP (Internal BGP) peering relationship with other 4over6 PE routers connected to the IPv6 backbone network 🔥.
the use of MP-iBGP suggests that the participating 4over6 PE routers that share a route reflector or form a full mesh of TCP connections are in the same autonomous system (AS). lowkey the wild part is that this implementation is only deployed over a single AS 🙈. that wasn't an intentional design constraint though. it just reflected the single AS topology of the CNGI-CERNET2 (China Next Generation Internet - China Education and Research Network) national IPv6 backbone that was used for testing and deploying this solution 🌸.
3.3.1. Receiving Routing Information from Local CE 💅
when a 4over6 PE router learns routing info from the locally attached IPv4 access networks, the 4over6 MP-iBGP entity should process the info like this:
- install and maintain local IPv4 routing info in the IPv4 routing database 📚.
- install and maintain new entries in the encapsulation table. each entry should consist of the IPv4 prefix and the local IPv6 VIF address 🧠.
- advertise the new contents of the local encapsulation table in the form of
MP_REACH_NLRIupdate information to remote 4over6 PE routers. the format of these updates is as follows:AFI = 1 (IPv4)SAFI = 67 (4over6)NLRI = IPv4 network prefixNetwork Address of Next Hop = IPv6 address of its 4over6 VIF
- a new Subsequent Address Family Identifier (SAFI) BGP 4over6 (67) has been assigned by IANA 🎉. we call a BGP update with a SAFI of 67 "4over6 routing information" 🫶.
3.3.2. Receiving 4over6 Routing Information from a Remote 4over6 PE 🦋
a local 4over6 PE router receives MP_REACH_NLRI updates from remote 4over6 routers, and it uses that info to populate its local encapsulation table and the BGP routing database 🧚. after the received attribute gets validated for correctness, these steps update the local encapsulation table and push new info into the local IPv4 routing table:
- validate the received BGP update packet as 4over6 routing information by
AFI = 1 (IPv4)andSAFI = 67 (4over6)✅. - extract the IPv4 network address from the NLRI field and install it as the IPv4 network prefix 🍓.
- extract the IPv6 address from the Network Address of the Next Hop field and place it as an associated entry next to the IPv4 network index. (note, this describes the update of the local encapsulation table 👀.)
- install and maintain a new entry in the encapsulation table with the extracted IPv4 prefix and its corresponding IPv6 address 💖.
- redistribute the new 4over6 routing information to the local IPv4 routing table. set the destination network prefix as the extracted IPv4 prefix, set the Next Hop as
Null, and Set theOUTPUTInterface as the 4over6 VIF on the local 4over6 PE router 🔥.
so when an ingress 4over6 PE router receives an IPv4 packet, the lookup in its IPv4 routing table comes back with the local 4over6 VIF as the output interface. that's when the incoming IPv4 packet gets encapsulated with a new IPv6 header, as indicated in the encapsulation table 🌈✨.
4. 4over6 Deployment Experience 🚀
4.1. CNGI-CERNET2 🍓
a prototype of the 4over6 solution is implemented and deployed on CNGI-CERNET2 👑. CNGI-CERNET2 is one of the China Next Generation Internet (CNGI) backbones, operated by the China Education and Research Network (CERNET) 🎀. it connects approximately 25 core nodes distributed in 20 cities in China at speeds of 2.5-10 Gb/s, which is literally so fast 😭. the CNGI-CERNET2 backbone is IPv6-only, with some attached customer premise networks (CPNs) being dual stack 🦋. the CNGI-CERNET2 backbone, the attached CNGI-CERNET2 CPNs, and CNGI-6IX Exchange all have globally unique AS numbers 💜. this IPv6 backbone is used to provide transit IPv4 services for customer IPv4 networks connected to the backbone via 4over6 PE routers 🧚.
4.2. 4over6 Testbed on the CNGI-CERNET2 IPv6 Network ✨
okay so bestie, Figure 5 is the map of the 4over6 deployment 🗺️ and it's giving organized chaos 😭
+-----------------------------------------------------+
| IPv6 (CERNET2) |
| |
+-----------------------------------------------------+
| | | |
Tsinghua|Univ. Peking|Univ. SJTU| Southeast|Univ.
+------+ +------+ +------+ +------+
|4over6| ... |4over6| |4over6| ... |4over6|
|router| |router| |router| |router|
+------+ +------+ +------+ +------+
| | | |
| | | |
| | | |
+-----------+ +-----------+ +-----------+ +-----------+
|IPv4 access| ... |IPv4 access| |IPv4 access| ... |IPv4 access|
| network | | network | | network | | network |
+-----------+ +-----------+ +-----------+ +-----------+
|
+----------------------+
| IPv4 (Internet) |
| |
+----------------------+
Figure 5: 4over6 Deployment Network Topologyso the IPv4-only access networks have servers and clients running all kinds of apps 💻✨ and the 4over6 PE routers are chilling at 8 x IPv6 nodes of CNGI-CERNET2, spread across seven universities and five cities across China 🇨🇳🎀 some of the IPv4 access networks hook up to both IPv6 and IPv4 networks, and others only plug into the IPv6 backbone 🔌 and in the deployment, users in different IPv4 networks could talk to each other through 4over6 tunnels 🫶
4.3. Deployment Experiences 💌
a bunch of 4over6 PE routers got deployed and configured to support the 4over6 transit solution 🚀 MP-BGP peerings got set up, and the 4over6 SAFI information got distributed successfully 🙌 checking the BGP routing and encapsulation tables confirmed that the right entries were sent and received 🧾 and ICMP ping traffic showed that IPv4 packets were successfully transiting the IPv6 backbone 🦋
other application protocols got tested too, and they were literally slaying 💅
- HTTP. a client running Internet Explorer in one IPv4 client network could access and download multiple objects from an HTTP server sitting in another IPv4 client network 🌐
- P2P. BitComet software on several PCs in different IPv4 client networks could find each other and share files 📂
other protocols, including FTP, SSH, IM (e.g., MSN, Google Talk), and Multimedia Streaming, all functioned correctly ✅ no notes, fr fr 🎀
5. Ongoing Experiment 🔮
okay so after that successful experiment, we're planning two more experiments, and I'm lowkey obsessed 🤩
- Inter-AS 4over6 🌍
the above experiment only got deployed over a single AS 🙈 but as the network grows, there could be multiple ASes between the edge networks. the thing is, the Next Hop field in MP-BGP currently indicates the tunnel endpoint in the 4over6 technology, but in the Inter-AS scenario, the tunnel endpoint needs to be separated from the Next Hop field 🫠 also, since 4over6 lives on the router running MP-BGP, supporting 4over6 on each Autonomous System Border Router (ASBR) will be a main concern in the Inter-AS experiment 👀 we might consider different situations: (1) some ASBRs do not support 4over6; (2) ASBRs only support the 4over6 control plane (i.e., MP-BGP extension of 4over6) rather than the 4over6 data plane; (3) ASBRs support both the control plane and the data plane for 4over6 🧚
- Multicast 4over6 📡
the current 4over6 technology only supports unicast routing and data forwarding 🥺 with network-layer multicast getting deployed in multiple IPv4 edge networks, we need to extend 4over6 to support multicast, including both multicast tree manipulation on the control plane and multicast traffic forwarding on the data plane 💜 building on the current unicast 4over6 technology, which gives the edge networks unicast connectivity over the backbone in another address family, multicast 4over6 will focus on the mapping technologies between the multicast groups in the different address families 🦄
6. Relationship to Softwire Mesh Effort 🫧
the 4over6 solution got presented at the IETF Softwires Working Group Interim meeting in Hong Kong in January 2006 🇭🇰 and this large-scale implementation and deployment clearly showed that MP-BGP could be employed to support tunnel setup in a scalable fashion across an IPv6 backbone 📈 but honestly the most important part was the use-case presented: an IPv6 backbone that offers transit to attached client IPv4 networks 👑
the 4over6 solution can be viewed as a precursor to the Softwire Mesh Framework proposed in the softwire problem statement [RFC4925] 🌱 however, there are several differences between this solution and the effort that came out of the Softwires Working Group called "softwire Mesh Framework" [RFC5565], plus the related solutions [RFC5512] [RFC5549] 🧩
- MP-BGP Extensions. 4over6 uses a new SAFI (BGP 4over6) to convey client IPv4 prefixes between 4over6 PE routers 🎯 Softwire Mesh keeps the original AFI-SAFI designations, but it uses a modified MP_REACH_NLRI format to convey IPv4 Network Layer Reachability Information (NLRI) prefix information with an IPv6 next_hop address [RFC5549] 🫶
- Encapsulation. 4over6 assumes IP-in-IP, or it's possible to configure Generic Routing Encapsulation (GRE) 🎀 Softwires uses those two scenarios configured locally or for IP headers that require dynamic updating 🔄 as a result, the BGP encapsulation SAFI is introduced in [RFC5512] 🙌
- Multicast. the basic 4over6 solution only implemented unicast communications 🥲 the multicast communications are specified in the Softwire Mesh Framework and are also supported by the multicast extension of 4over6 ✨
- Use-Cases. the 4over6 solution in this document specifies the 4over6 use-case, which is also pretty easy to extend for the use-case of 6over4 🌈 the Softwire Mesh Framework supports both 4over6 and 6over4 💅
7. IANA Considerations 📋
a new SAFI value (67) has been assigned by IANA for the BGP 4over6 SAFI 🎉
8. Security Considerations 🚨
⚠️ okay bestie, this part is SERIOUS, read it twice 😭
tunneling mechanisms, especially automatic ones, often have potential problems of Distributed Denial of Service (DDoS) attacks on the tunnel entry-point or tunnel exit-point 💀 as the advantage, the BGP 4over6 extension doesn't allocate resources to a single flow or maintain state for a flow 🧠 however, since the IPv6 tunnel endpoints are globally reachable IPv6 addresses, it would be trivial to spoof IPv4 packets by encapsulating and sending them over IPv6 to the tunnel interface 😱 this could bypass IPv4 Reverse Path Forwarding (RPF) or other antispoofing techniques 🙈 also, any IPv4 filters may be bypassed 🫣
an iBGP peering relationship may be maintained over IPsec or other secure communications 🔐
9. Conclusion 🎀
the emerging and growing deployment of IPv6 networks, especially IPv6 backbone networks, will introduce cases where connectivity with IPv4 networks is desired 🌸 some IPv6 backbones will need to offer transit services to attached IPv4 access networks 🛣️ the 4over6 solution in this document supports that through an extension to MP-BGP that conveys IPv4 routing information along with an associated IPv6 address 💖 basic IP encapsulation is used in the data plane as IPv4 packets are tunneled through the IPv6 backbone 🦋
an actual implementation has been developed and deployed on the CNGI-CERNET2 IPv6 backbone 🏆 we did it, bestie 🥹✨
10. Acknowledgements 💜
during the design procedure of the 4over6 framework and the definition of the BGP-MP 4over6 extension, Professor Ke Xu gave the authors many valuable comments 🫶 the support of the IETF Softwires WG is also gratefully acknowledged, with special thanks to David Ward, Alain Durand, and Mark Townsley for their rich experience and knowledge in this field 🙏 Yakov Rekhter provided helpful comments and advice 💅 and Mark Townsley reviewed this document carefully and gave the authors a lot of valuable comments, which were super important for improving this document 🌟
the deployment and test for the prototype system was conducted among seven universities: Tsinghua University, Peking University, Beijing University of Post and Telecommunications, Shanghai Jiaotong University, Huazhong University of Science and Technology, Southeast University, and South China University of Technology 🎓 the authors would like to thank everyone involved in this effort at these universities 🧚♀️
11. Normative References 📚
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, December 1998.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, January 2007.
[RFC4925] Li, X., Dawkins, S., Ward, D., and A. Durand, "Softwire Problem Statement", RFC 4925, July 2007.
[RFC5512] Mohapatra, P. and E. Rosen, "The BGP Encapsulation Subsequent Address Family Identifier (SAFI) and the BGP Tunnel Encapsulation Attribute", RFC 5512, April 2009.
[RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network Layer Reachability Information with an IPv6 Next Hop", RFC 5549, May 2009.
[RFC5565] Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh Framework", RFC 5565, June 2009.
Authors' Addresses 🖊️
Jianping Wu
Tsinghua University
Department of Computer Science, Tsinghua University
Beijing 100084
P.R. China
Phone: +86-10-6278-5983
EMail: jianping@cernet.edu.cn
Yong Cui
Tsinghua University
Department of Computer Science, Tsinghua University
Beijing 100084
P.R. China
Phone: +86-10-6278-5822
EMail: cy@csnet1.cs.tsinghua.edu.cn
Xing Li
Tsinghua University
Department of Electronic Engineering, Tsinghua University
Beijing 100084
P.R. China
Phone: +86-10-6278-5983
EMail: xing@cernet.edu.cn
Mingwei Xu
Tsinghua University
Department of Computer Science, Tsinghua University
Beijing 100084
P.R. China
Phone: +86-10-6278-5822
EMail: xmw@csnet1.cs.tsinghua.edu.cn
Chris Metz
Cisco Systems, Inc.
3700 Cisco Way
San Jose, CA 95134
USA
EMail: chmetz@cisco.comthat's the whole RFC, bestie 🌈💖
📦 where this page comes from
- ietf: rfc5747 2010-03
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms