TRILL working group L. Dunbar
Internet Draft D. Eastlake
Intended status: Standard Track Huawei
Expires: Sept 2013 Radia Perlman
Intel
I. Gashinsky
Yahoo
February 22, 2013
Directory Assisted TRILL Encapsulation
draft-dunbar-trill-directory-assisted-encap-03.txt
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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 ................................................ 2
2. Terminology ................................................. 3
3. Directory Assistance to Non-RBridge ......................... 3
4. Source Nickname in Frames Encapsulated by Non-RBridge Nodes.. 6
5. Conclusion and Recommendation................................ 6
6. Manageability Considerations................................. 6
7. Security Considerations...................................... 6
8. IANA Considerations ......................................... 6
9. Acknowledgments ............................................. 6
10. References ................................................. 7
Authors' Addresses ............................................. 7
Intellectual Property Statement................................. 8
Disclaimer of Validity ......................................... 9
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
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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 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.
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\ +-------+ +------+ TRILL Domain/
\ +/------+ | +/-----+ | /
\ | Aggr11| + ----- |AggrN1| + /
\ +---+---+/ +------+/ /
\ / \ / \ /
\ / \ / \ /
\ +---+ +---+ +---+ +---+ /
\- |T11|... |T1x| |T21| .. |T2y|---
+---+ +---+ +---+ +---+
| | | |
+-|-+ +-|-+ +-|-+ +-|-+
| |... | V | | V | .. | V |<-Virtual Switch
+---+ +---+ +---+ +---+
| |... | 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 need to flood
the received Ethernet data frames to TRILL domain when the DA in the
Ethernet data frames is unknown. 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.
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
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not encapsulate and forward native Ethernet 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
native frame from the received TRILL frame and forwards the
decapsulated Ethernet frame to the target attached to its edge
ports.
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, the Ethernet frame is forwarded
per IEEE802.1Q.
+------------+--------+---------+---------+--+-------+----+
|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.
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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.
5. Conclusion and Recommendation
When directory service is available, nodes that are outside TRILL
domain, i.e. don't participate in TRILL IS/IS routing protocol,
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 many 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.
6. Manageability Considerations
TBD.
7. Security Considerations
TBD.
8. IANA Considerations
TBD
9. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
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10. 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
[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: ldunbar@huawei.com
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Donald Eastlake
Huawei Technologies
155 Beaver Street
Milford, MA 01757 USA
Phone: 1-508-333-2270
Email: d3e3e3@gmail.com
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: igor@yahoo-inc.com
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