Internet DRAFT - draft-xl-trill-over-wan
draft-xl-trill-over-wan
Network Working Group X. Wan
Internet-Draft X. Yang
Intended status: Standards Track HangZhou H3C Co. Limited
Expires: December 10, 2012 V. Manral
A. Retana
Hewlett-Packard Co.
June 8, 2012
Extending TRILL over WAN
draft-xl-trill-over-wan-01.txt
Abstract
TRILL is a key technology for large-scale layer 2 networking within a
data center, TRILL over WAN_(ToW) provides a scalable and simple
solution that interconnect multiple TRILL networks to form a single
TRILL domain using the currently deployed enterprise or service
provider networks. This document provides an overview of this
solution.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 10, 2012.
Copyright Notice
Copyright (c) 2012 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
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to this document. Code Components extracted from this document must
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Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Provider Control Plane . . . . . . . . . . . . . . . . . . 5
3.2. Overlay Control Plane . . . . . . . . . . . . . . . . . . 5
3.2.1. Edge Device Discovery and Adjacency setup . . . . . . 5
3.2.2. Control Plane Packet Encapsulation and Relay . . . . . 5
4. Data Plane . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Forwarding Process . . . . . . . . . . . . . . . . . . . . 8
4.2.1. Forwarding from an Internal Link to the Overlay . . . 8
4.2.2. Forwarding from the Overlay Link to an Internal
Link . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2.3. Multicast Packet Flows . . . . . . . . . . . . . . . . 8
4.2.4. Broadcast Packet Flows . . . . . . . . . . . . . . . . 8
4.2.5. Mac Address Learning . . . . . . . . . . . . . . . . . 8
4.2.6. Multi-homing . . . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6.1. Failure Separation . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
8. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Overview
TRILL over WAN is a technology for supporting L2 VPNs over an L2/L3
infrastructure. It provides an "over-the-top" method of doing
virtualization among several sites where the routing and forwarding
state is maintained at the network edge, but not within the site or
in the core.
TRILL over WAN can reside in a small number of device at the edge
between TRILL sites and the core, we call these devices "Joint
Devices" which perform typical transit Rbridges functions(nickname-
based forwarding) and perform overlay functions on their core facing
interfaces.
TRILL traffic which requires traversing the WAN to reach its
destination, is prepended with an IP header. As shown in figure1, if
a destination RBridge(Nickname) is reachable via Joint Device S2(with
a core facing IP address of IPB), other Joint Devices forwarding
traffic to such Rbridge will add on IP header with a destination IP
address of IPB and forward the traffic into the core. The core will
forward traffic based on IP address IPB, once the traffic makes it to
Joint Device S2 it will be stripped of the overlay IP header and it
will be forwarded into the site in the same way a regular RBridge
would forward a packet. Broadcast or multicast traffic is
encapsulated with a multicast header and follows a similar process.
+---+ +---+IPA --------- IPB +---+ +---+
|S10|-----|S1 |----/ IP Core \----|S2 |-----|S20|
+---+ ^ +---+ \ Network / +---+ ^ +---+
| --------- |
| |
| +------------+ |
| | DA=IPB | |
| +------------+ |
| | SA=IPA | |
+------------+ +------------+ +------------+
|Outer Eth. | |Outer Eth. | |Outer Eth. |
|Header | |Header | |Header |
+------------+ +------------+ +------------+
|TRILL Header| |TRILL Header| |TRILL Header|
+------------+ +------------+ +------------+
|Inner Eth. | |Inner Eth. | |Inner Eth. |
|Frame | |Frame | |Frame |
+------------+ +------------+ +------------+
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Figure 1: Traffic encapsulation
The key piece that TRILL over WAN adds is the state to map a given
egress Nickname to an IP address of the Joint Device behind which
that egress Nickname is located. TRILL over WAN forwarding is a
function of mapping a destination Nickname to a Joint Device IP
address in the overlay network.
To achieve this, a control plane is required to exchange the
reachability information among different Joint Devices. After Joint
Device discovery and adjacency setup, the virtual links to neighbor
Joint Devices will be treated as TRILL interface, and the TRILL's
control plane runs over these virtual links. Through these steps,
all the Rbridges in multiple site forms a single TRILL domain. Each
Rbridge (including Joint Device) calculates its TRILL forwarding
table independently. Figure 2 shows what the resulting forwarding
tables look like in a simple example.
+---+ L11+---+IPA --------- IPB +---+ L21+---+
|S10|----|S1 |----/ IP Core \----| S2|----|S20|
+---+ +---+ \ Network / +---+ +---+
---------
S1 S2
+----------------------+ +-------------------+
|Nickname |Interface | |Nickname |Interface|
+----------------------+ +-------------------+
| S10 | L11 | | S10 | IPA |
+----------------------+ +-------------------+
| S20 | IPB | | S20 | L21 |
+----------------------+ +-------------------+
| S1 | self | | S1 | IPA |
+----------------------+ +-------------------+
| S2 | IPB | | S2 | self |
+----------------------+ +-------------------+
Figure 2: Forwarding Tables
TRILL over WAN supports multi-homing for sites where one or more of
the Joint Devices connected to core network. It can support active-
active multi-homing capability and loop elimination by nature of
TRILL. No need to add other extra mechanism.
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2. Terminology
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 [RFC2119].
[[anchor2: NOTE TO RFC EDITOR: Please remove the following text
before publication.]]
Some ideas of this specification is being discussed on the EAI
mailing list. See https://www1.ietf.org/mailman/listinfo/ima for
information about subscribing. The list's archive is at
http://www1.ietf.org/mail-archive/web/ima/index.html.
3. Control Plane
3.1. Provider Control Plane
The provider control plane enables unicast reachability among the
Joint Devices and also provides the multicast group than makes Joint
Devices adjacent from the overlay control plane perspective. It also
provides the multicast trees in the core that will be used for
optimal forwarding of the TRILL data traffic.
3.2. Overlay Control Plane
The overlay control plane provides auto-discovery of the Joint
Devices that are members of an overlay VPN.
The TRILL control plane traffic between Joint Devices of different
sites will be carried over the virtual link.
Detailed to be added.
3.2.1. Edge Device Discovery and Adjacency setup
See draft-hasmit-otv-03 2.2.1.
3.2.2. Control Plane Packet Encapsulation and Relay
Any Jonit Device of the site is virtual link with the other Jonit
Devices of the other sites. Any Jonit Device should encapsulate the
ISIS routing information of its site, and then relay it to the other
Joint Devices of the other sites.
There is no different between the virtual links and the physical
links to the TRILL protocol. The TRILL protocol calculates the
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routing information among the whole TRILL domain.
4. Data Plane
4.1. Encapsulation
The encapsulation format is TRILL frame encapsulated in UDP inside of
IPv4 or IPv6.
The format of the UDP IPv4 encapsulation is as follows:
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service| Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |Flags| Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live | Protocol = 17 | Header Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source-site TRILL Joint Device IP Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination-site TRILL Joint Device (or multicast) Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port = xxxx | Dest Port = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP length | UDP Checksum = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|R|R|I|R|R|R| Overlay ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Ethernet Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| TRILL Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Ethernet Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Payload |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The format of the UDP IPv6 encapsulation is as follows:
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header=17| Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source-site TRILL Joint Device IPv6 Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination-site TRILL Joint Device (or multicast) Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port = xxxx | Dest Port = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|R|R|I|R|R|R| Overlay ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Ethernet Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| TRILL Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Ethernet Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Payload |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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4.2. Forwarding Process
4.2.1. Forwarding from an Internal Link to the Overlay
The forwarding within a site is normal TRILL forwarding, so here only
describes the forwarding from an Internal link to the Overlay Link,
or vice versa.
A Joint Device is a transit Rbridge from TRILL point of view. When a
TRILL packet is received from the internal interface, egress Nickname
is used to lookup the Nickname table which will yield a next-hop IP
address entry pointing to a remote Joint Device. Then the packet is
encapsulated with UDP/IP header and sent over the overlay interface
to destination Joint Device at Layer-3 as a regular IP packet.
4.2.2. Forwarding from the Overlay Link to an Internal Link
When a packet is received on the overlay interface, it will be IP
decapsulated to reveal the inner TRILL(including the outer MAC)
header for forwarding. The egress Nickname will used for forwarding,
the forwarding action is same as a transit RBridge.
4.2.3. Multicast Packet Flows
To be added.
4.2.4. Broadcast Packet Flows
To be added.
4.2.5. Mac Address Learning
The TRILL edge devices learn remote MAC addresses(including the MAC
addresses in other data centers) in data plane by hardware. In most
cases, the Joint device is like a transit RBridge, and doesn't learn
end host's MAC addresses. From DCI(Data Center Interconnect)
perspective, the Joint Device is DCI device at the same time, so
TRILL over WAN can relieve the pressure of MAC addresses table
capability in DCI device.
4.2.6. Multi-homing
In the situation of multi-homing shown as Figure 3, all the Joint
Devices can be active by the nature of TRILL.
Figure 4 shows what the resulting forwarding tables would look like
in the multi-homing example.
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+---+ L1 +---+ IPA -------- IPD +---+ +---+
|S10|----| S1|-------- / \ ---------|S4 |----|S21|
+---+ +---+ / \ +---+ +---+
\/L2 | IP Core | \/
/\ | Networ | /\
+---+ +---+ IPB \ / IPC +---+ +---+
|S11|----|S2 |-------- \ / ---------|S3 |----|S20|
+---+ +---+ -------- +---+ +---+
Figure 3: Multi-homing Scenario
S1
+----------------------+
|Nickname |Interface |
+----------------------+
| S1 | self |
+----------------------+
| S2 | - |
+----------------------+
| S3 | IPC |
+----------------------+
| S4 | IPD |
+----------------------+
| S10 | L1 |
+----------------------+
| S11 | L2 |
+----------------------+
| S20 | IPC/IPD |
+----------------------+
| S21 | IPC/IPD |
+----------------------+
Figure 4: Forwarding Table of S1
In S1 device, the traffic destinated to S10 and S21 have two next
hops, IPC and IPD. In forwarding process, hashing of TRILL packet
inner information will be used to determine which next hop IP address
to use. Thus, the ingress traffic will be load balanced between
multiple Joint Devices within a site.
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5. IANA Considerations
IANA need to allocate the following UDP Ports for the TRILL IS-IS and
Data channels:
UDP Port Protocol
TBD TRILL IS-IS Channel
TBD TRILL Data Channel
6. Security Considerations
6.1. Failure Separation
To be added.
7. Acknowledgements
Much of the wording herein was adapted from draft-hasmit-otv-03.
8. Normative References
[I-D.hasmit-otv]
Grover, H., Rao, D., Farinacci, D., and V. Moreno,
"Overlay Transport Virtualization", draft-hasmit-otv-03
(work in progress), July 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6325] Perlman, R., Eastlake, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, July 2011.
[RFC6326] Eastlake, D., Banerjee, A., Dutt, D., Perlman, R., and A.
Ghanwani, "Transparent Interconnection of Lots of Links
(TRILL) Use of IS-IS", RFC 6326, July 2011.
[RFC6327] Eastlake, D., Perlman, R., Ghanwani, A., Dutt, D., and V.
Manral, "Routing Bridges (RBridges): Adjacency", RFC 6327,
July 2011.
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Authors' Addresses
Xiaolan Wan
HangZhou H3C Co. Limited
No. 2 ChuangYe Road, HaiDian District
Beijing
P.R. China
Phone: +86 10 82774971
Email: wxlan@h3c.com
Xiaopeng Yang
HangZhou H3C Co. Limited
No. 2 ChuangYe Road, HaiDian District
Beijing
P.R. China
Phone: +86 10 82774963
Email: yxp@h3c.com
Vishwas Manral
Hewlett-Packard Co.
19111 Pruneridge Ave.
Cupertino, CA
USA
Email: vishwas.manral@hp.com
Alvaro Retana
Hewlett-Packard Co.
2610 Wycliff Road
Raleigh, NC
USA
Email: alvaro.retana@hp.com
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