Directory Assisted TRILL Encapsulation
Author(s): Igor Gashinsky, Linda Dunbar, Donald Eastlake, Radia Perlman
This draft describes how data center network can benefit from non-RBridge nodes performing TRILL encapsulation with assistance from directory service....
TRILL working group L. Dunbar Internet Draft D. Eastlake Intended status: Standard Track Huawei Expires: Sept 2014 Radia Perlman Intel I. Gashinsky Yahoo July 15, 2013 Directory Assisted TRILL Encapsulation draft-dunbar-trill-directory-assisted-encap-04.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright Notice Copyright (c) 2013 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 of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this Dunbar, et al Directory Assisted TRILL Encapsulation [Page 1] Internet-Draft Directory Assisted TRILL Encapsulation document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Abstract This draft describes how data center network can benefit from non-RBridge nodes performing TRILL encapsulation with assistance from directory service. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 0. The term ''TRILL'' and ''RBridge'' are used interchangeably in this document. The term ''subnet'' and ''VLAN'' are also used interchangeably because it is very common to map one subnet to one VLAN. Table of Contents 1. Introduction ................................................ 3 2. Terminology ................................................. 3 3. Directory Assistance to Non-RBridge ......................... 3 4. Source Nickname in Frames Encapsulated by Non-RBridge Nodes.. 6 5. Benefits of Non-RBridge encapsulating TRILL header .......... 7 5.1. Avoid Nickname Exhaustion Issue ........................ 7 5.2. Reduce FDB size for switches on Bridged LANs ........... 7 6. Conclusion and Recommendation ............................... 8 7. Manageability Considerations................................. 8 8. Security Considerations...................................... 8 9. IANA Considerations ......................................... 8 10. Acknowledgments ............................................ 8 11. References ................................................. 8 Authors' Addresses ............................................. 9 Intellectual Property Statement................................ 10 Disclaimer of Liability........................................ 10 Dunbar Expires Sept15, 2014 [Page 2] Internet-Draft Directory Assisted TRILL Encapsulation 1. Introduction This draft describes how data center network can benefit from non-RBridge nodes performing TRILL encapsulation with assistance from directory service. [RBridge-directory] describes the framework for RBridge edge to get MAC&VLAN<->RBridgeEdge mapping from a directory service in data center environment instead of flooding unknown DAs across TRILL domain. When directory is used, any node, even non- RBridge node, can perform the TRILL encapsulation. This draft is to demonstrate the benefits of non-RBridge nodes performing TRILL encapsulation. 2. Terminology AF Appointed Forwarder RBridge port Bridge: IEEE 802.1Q compliant device. In this draft, Bridge is used interchangeably with Layer 2 switch. DA: Destination Address DC: Data Center EoR: End of Row switches in data center. Also known as Aggregation switches in some data centers FDB: Filtering Database for Bridge or Layer 2 switch Host: Application running on a physical server or a virtual machine. A host usually has at least one IP address and at least one MAC address. SA: Source Address ToR: Top of Rack Switch in data center. It is also known as access switches in some data centers. VM: Virtual Machines 3. Directory Assistance to Non-RBridge With directory assistance [RBridge-Directory], a non-RBridge can determine if a packet needs to be forwarded across the RBridge domain. Suppose the RBridge domain boundary starts at Dunbar Expires Sept15, 2014 [Page 3] Internet-Draft Directory Assisted TRILL Encapsulation network switches (i.e. not virtual switches embedded on servers), a directory can assist Virtual Switches embedded on servers to encapsulate proper TRILL header by providing the information of the egress RBridge edge to which the target is attached. If a target is not attached to other RBridge edge nodes based on the directory [RBridge-Directory], the non- RBridge node can forward the data frames natively, i.e. not encapsulating any TRILL header. \ +-------+ +------+ TRILL Domain/ \ +/------+ | +/-----+ | / \ | Aggr11| + ----- |AggrN1| + / \ +---+---+/ +------+/ / \ / \ / \ / \ / \ / \ / \ +---+ +---+ +---+ +---+ / \- |T11|... |T1x| |T21| .. |T2y|--- +---+ +---+ +---+ +---+ | | | | +-|-+ +-|-+ +-|-+ +-|-+ | |... | V | | V | .. | V |<-VirtualSwitch +---+ +---+ +---+ +---+ | |... | V | | V | .. | V | +---+ +---+ +---+ +---+ | |... | V | | V | .. | V | +---+ +---+ +---+ +---+ Figure 1: TRILL domain in typical Data Center Network When a TRILL encapsulated data packet reaches the ingress RBridge, the ingress RBridge can simply forward the pre- encapsulated packet to the RBridge that is specified in the DA field of the TRILL header of the data frame. When the ingress RBridge receives a native Ethernet frame, it only forward the data frame to the directly attached bridged LAN. Under this environment, the ingress RBridge doesn't flood or send the received Ethernet data frames to TRILL domain when the DA in the Ethernet data frames is unknown or instructed by the directory not to be sent across TRILL domain. Under this scheme, for an RBridge with multiple ports connected to a bridged LAN, data frames received from TRILL domain, decapsulated and forwarded to the bridged LAN via one port, and flooded back to the RBridge via another port, won't be encapsulated again and forwarded back TRILL domain. Dunbar Expires Sept15, 2014 [Page 4] Internet-Draft Directory Assisted TRILL Encapsulation That means there is no need to worry about AF ports and all RBridge edge ports connected to one bridged LAN can receive and forward pre-encapsulated traffic, which greatly improves the overall network utilization. Note: [RBridge] Section 4.6.2 Bullet 8 specifies that an RBridge port can be configured to accept TRILL encapsulated frames from a neighbor that is not an RBridge. When data frames do not need to be sent across RBridge domain, they are switched by all nodes/ports per IEEE802.1Q and RBridge edge will not encapsulate and forward those data frames across RBridge domain. When a pre-encapsulated TRILL frame arrives at an RBridge whose nickname matches with the destination nickname in the TRILL header, the processing is exactly same as normal, i.e. it decapsulates the received TRILL frame and forwards the decapsulated Ethernet frame to the target attached to its edge ports. If the DA of the decapsulated Ethernet frame is not in the egress RBridge's FDB, the egress RBridge can flood the decapsulated Ethernet frame to all hosts attached. We call a node that only performs the TRILL encapsulation but doesn't participate in RBridge's IS-IS routing a ''TRILL Encapsulating node'' or ''Simplified RBridge''. The TRILL Encapsulating Node gets the MAC&VLAN<->RBridgeEdge mapping table pushed down or pulled from directory servers [RBridge- directory]. Upon receiving a native Ethernet frame, the TRILL Encapsulating Node checks the MAC&VLAN<->RBridgeEdge mapping table, and perform the corresponding TRILL encapsulation if the entry is found in the mapping table. If the destination address and VLAN of the received Ethernet frame doesn't exist in the mapping table and no positive reply from pulling request to a directory, the Ethernet frame is forwarded per IEEE802.1Q. Dunbar Expires Sept15, 2014 [Page 5] Internet-Draft Directory Assisted TRILL Encapsulation +------------+--------+---------+---------+--+-------+----+ |OuterEtherHd|TRILL HD| InnerDA | InnerSA |..|Payload| FCS| +------------+--------+---------+---------+--+-------+----+ ^ | |<Inner Ether Header> | | | | +-------+ TRILL +------+ | | R1 |-----------| R2 | Decapsulate TRILL | +---+---+ domain +------+ header | | | +----------| | | | +-----+ +-----+ Non-RBridge node:|T12 | | T22 | Encapsulate TRILL+-----+ +-----+ Header for data Frames to traverse TRILL domain. 4. Source Nickname in Frames Encapsulated by Non-RBridge Nodes The TRILL header includes a Source RBridge's Nickname (ingress) and Destination RBridge's Nickname (egress). When a TRILL header is added by a non-RBridge node, using the Ingress RBridge edge node's nickname in the source address field will make the ingress RBridge node receive TRILL frames with its own nickname in the frames' source address field, which can be confusing. To avoid confusion of edge RBridges receiving TRILL encapsulated frames with their own nickname in the frames' source address field from neighboring non-RBridge nodes, a new nickname can be given to an RBridge edge node, e.g. Phantom Nickname, to represent all the TRILL Encapsulating Nodes attached to the RBridge edge node. When the Phantom Nickname is used in the Source Address field of a TRILL frame, it is understood that the TRILL encapsulation is actually done by a non-RBridge node which is attached to an edge port of an RBridge Ingress node. Dunbar Expires Sept15, 2014 [Page 6] Internet-Draft Directory Assisted TRILL Encapsulation 5. Benefits of Non-RBridge encapsulating TRILL header 5.1. Avoid Nickname Exhaustion Issue For a large Data Center with hundreds of thousands of virtualized servers, setting TRILL boundary at the servers' virtual switches will create a TRILL domain with hundreds of thousands of RBridge nodes, which has issues of TRILL Nicknames exhaustion and challenges to IS-IS. Setting TRILL boundary at aggregation switches that have many virtualized servers attached can limit the number of RBridge nodes in a TRILL domain, but introduce the issues of very large MAC&VLAN<- >RBridgeEdge mapping table to be maintained by RBridge edge nodes and the necessity of enforcing AF ports. Allowing Non-RBridge nodes to pre-encapsulate data frames with TRILL header makes it possible to have a TRILL domain with reasonable number of RBridge nodes in a large data center. All the TRILL encapsulating nodes attached to one RBridge are represented by one TRILL nickname, i.e. Phantom Nickname, which avoids the Nickname exhaustion problem. 5.2. Reduce FDB size for switches on Bridged LANs When hosts in a VLAN (or subnet) span across multiple RBridge edge nodes and each RBridge edge has multiple VLANs enabled, the switches on the bridged LANs attached to the RBridge edge are exposed to all MAC addresses among all the VLANs enabled. For example, for an Access switch with 40 physical servers attached, where each server has 100 VMs, there are 4000 hosts under the Access Switch. If indeed hosts/VMs can be moved anywhere, the worst case for the Access Switch is when all those 4000 VMs belong to different VLANs, i.e. the access switch has 4000 VLANs enabled. If each VLAN has 200 hosts, this access switch's MAC table potentially has 200*4000 = 800,000 entries. However, if the virtual switches on server pre-encapsulate the data frames towards hosts attached to other RBridge Edge nodes with TRILL header, the outer MAC DA of those TRILL encapsulated data frames will be the MAC address of the local RBridge edge, i.e. the ingress RBridge. Therefore, the switches on the local bridged LAN don't need to keep the MAC entries for remote hosts attached to other RBridge edges. Dunbar Expires Sept15, 2014 [Page 7] Internet-Draft Directory Assisted TRILL Encapsulation There are multiple ways for local switches to avoid adding remote hosts' MAC to their FDB. One simple way is by disabling learning on source addresses. The local switches can be pre- installed with MAC addresses of local hosts with the assistance of directory. 6. Conclusion and Recommendation When directory service is available, nodes outside TRILL domain become capable of encapsulating TRILL header for data frames destined for remote RBridges that is not on the same bridged LAN. The non-RBridge encapsulation approach is especially useful when there are a large number of servers in a data center equipped with hypervisor-based virtual switches. It is relatively easy for virtual switches, which are usually software based, to get directory assistance and perform network address encapsulation. 7. Manageability Considerations TBD. 8. Security Considerations TBD. 9. IANA Considerations TBD 10. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. 11. References [RBridge-Directory] Dunbar, et, al ''TRILL (Transparent Interconnection of Lots of Links) Edge Directory Assistance Framework'', < draft-ietf-trill-directory-framework-03>, March, 2013 Dunbar Expires Sept15, 2014 [Page 8] Internet-Draft Directory Assisted TRILL Encapsulation [RBridges] Perlman, et, al ''RBridge: Base Protocol Specification'', <draft-ietf-trill-rbridge-protocol-16.txt>, March, 2010 [RBridges-AF] Perlman, et, al ''RBridges: Appointed Forwarders'', <draft-ietf-trill-rbridge-af-02.txt>, April 2011 [ARMD-Problem] Dunbar, et,al, ''Address Resolution for Large Data Center Problem Statement'', Oct 2010. [ARP reduction] Shah, et. al., "ARP Broadcast Reduction for Large Data Centers", Oct 2010 Authors' Addresses Linda Dunbar Huawei Technologies 1700 Alma Drive, Suite 500 Plano, TX 75075, USA Phone: (972) 543 5849 Email: email@example.com Donald Eastlake Huawei Technologies 155 Beaver Street Milford, MA 01757 USA Phone: 1-508-333-2270 Email: firstname.lastname@example.org Dunbar Expires Sept15, 2014 [Page 9] Internet-Draft Directory Assisted TRILL Encapsulation Radia Perlman Intel Labs 2200 Mission College Blvd. Santa Clara, CA 95054-1549 USA Phone: +1-408-765-8080 Email: Radia@alum.mit.edu Igor Gashinsky Yahoo 45 West 18th Street 6th floor New York, NY 10011 Email: email@example.com Intellectual Property Statement The IETF Trust takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in any IETF Document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Copies of Intellectual Property disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement any standard or specification contained in an IETF Document. Please address the information to the IETF at firstname.lastname@example.org. Disclaimer of Liability All IETF Documents and the information contained therein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE Dunbar Expires Sept15, 2014 [Page 10] Internet-Draft Directory Assisted TRILL Encapsulation INFORMATION THEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Dunbar Expires Sept15, 2014 [Page 11]