Internet DRAFT - draft-zhang-l2vpn-vpls-bd-tagging
draft-zhang-l2vpn-vpls-bd-tagging
INTERNET-DRAFT Mingui Zhang
Intended Status: Informational Bin Wang
Liang Xia
Huawei
Jie Hu
China Telecom
Expires: February 13, 2015 August 12, 2014
Tagging Customer Bridge Domains in VPLS
draft-zhang-l2vpn-vpls-bd-tagging-02.txt
Abstract
This document proposes to use Customer VLAN ID as an identifier for
traffic isolation in Virtual Private LAN Service (VPLS). In this way,
multiple bridge domains of customers can share a single VPLS instance
while their traffic are separated. With this proposal, Service
Providers can be relieved from the heavy provisioning overhead of
large number of pseudowires in the environment where a mass of bridge
domains need be connected.
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/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Copyright and License Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
Mingui Zhang, et al Expires February 13, 2015 [Page 1]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
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 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Acronyms and Terminology . . . . . . . . . . . . . . . . . . . 3
2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PE Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Use Cases of U-tag Awareness in VPLS . . . . . . . . . . . . . 4
4.1. No Duplicated MAC Address . . . . . . . . . . . . . . . . . 4
4.2. Scalable Interconnection of L2 Sites . . . . . . . . . . . 5
4.3. BUM Traffic Scoped per BD . . . . . . . . . . . . . . . . . 5
4.3.1. Advertising Interested VLANs in LDP . . . . . . . . . . 5
4.3.2. Dynamic VLAN Registration with MVRP . . . . . . . . . . 5
4.4. Per C-VLAN MAC Withdraw . . . . . . . . . . . . . . . . . . 6
5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 6
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Mingui Zhang, et al Expires February 13, 2015 [Page 2]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
1. Introduction
VPLS has been widely used to connect customers' bridge domains.
Traffic segregation for customers is performed on a per VPLS instance
basis. In the environment (e.g., Data Center Network) where a mass of
customers multiplied with a plenty of bridge domains are to be
connected, a large number of PWs need be maintained. Service
Providers are therefore suffering from scalability issue.
This proposal suggests the Customer VLAN ID (U-tag) is used as an
additional de-multiplexor for traffic segregation in VPLS. By doing
this, multiple BDs can share the same VPLS instance while their
traffic are isolated. This method can greatly reduce the number of
PWs therefore reduce the provisioning overhead for operators. Use
cases of this method are given in the document.
Two options arising from the industry are covered in the discussion.
The first one is proposed in [V-aware]. It extends the LDP control
plane for PEs to advertise supported VLANs. The second option makes
use of VLAN registration protocol, such as [MVRP], to exchange
supported C-VLANs between PEs.
2. Acronyms and Terminology
2.1. Acronyms
MVRP: Multiple VLAN Registration Protocol
BD: Bridge Domain/Broadcast Domain
PW: Pseudowire
VSI: Virtual Switch Instance
U-tag: Customer VLAN ID
C-VLAN: Customer VLAN
BUM: Broadcast, Unknown unicast and Multicast
VLL: Virtual Leased Line
2.2. 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].
3. PE Model
Mingui Zhang, et al Expires February 13, 2015 [Page 3]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
........................
. +--------+ .
L2 +--------| BD1 +------------------ PW
L2 +--------| | .
L2 +---+ . +--------+ VSI.
| ........................
|
| ........................
| . +---+---+ .
| . +--------+ |100|PKT| .
+----| BD11 | +---+---+ .
L2 +--------|Utag=100+--------------+
. +--------+ . |
. +---+---+ . |
. +--------+ |200|PKT| . |
L2 +--------| BD11 | +---+---+ . |
. |Utag=200+--------------+--- tagged PW
. +--------+ . |
. +---+---+ . |
. +--------+ |300|PKT| . |
L2 +--------| BD11 | +---+---+ . |
L2 +--------|Utag=300+--------------+
. +--------+ .
. VSI.
........................
L2 +-----------VLL---------------------- PW
Figure 3.1: U-tag is used as the service de-multiplexor in tagged PW
In Figure 3.1, an example is used to shown that the Customer VLAN ID
(U-tag) is used as an finer grained de-multiplexor for traffic
segregation. Therefore, multiple customer BDs can be integrated into
one VSI while their traffic is isolated.
4. Use Cases of U-tag Awareness in VPLS
4.1. No Duplicated MAC Address
One MAC address might be used by multiple hosts in different customer
VLANs (C-VLAN). This is illegal but it is the headache reality for
providers. In the virtualization environment, Virtual Machines (VM)
are more likely to have duplicated MAC addresses. When these
hosts/VMs join in the same VSI of a PE, the PE will see MAC address
duplication. In order to overcome this issue, the PE has to adopt
qualified learning [RFC4762], i.e., the PE has to set up one VSI per
C-VLAN. This brings the scalability issue as discussed in Section
4.2.
Mingui Zhang, et al Expires February 13, 2015 [Page 4]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
If the PE uses U-tag as the de-multiplexor to isolate traffic of
customers' BDs, above MAC address duplication issue can be avoided.
4.2. Scalable Interconnection of L2 Sites
For the qualified learning, providers need set up one PW per C-VLAN.
When there is a large number of customers multiplied by C-VLANs
interconnected using VPLS, a mass of PWs need be maintained. It
brings heavy operating overhead to providers.
In this document, U-tag is used to distinguish BDs in VPLS. In this
way, traffic from multiple C-VLANs can be handled by a single VPLS.
As shown in Figure 3.1, one PW is set up for each VSI and this VSI
may be an integration of multiple BDs. Operating overhead of
operators can be greatly reduced.
4.3. BUM Traffic Scoped per BD
Traditional VPLS limits a broadcast domain scope per PW. Suppose a
customer has four sites in New York, Chicago, Atlanta and Dallas. BD1
= {New York, Chicago and Atlanta} while BD2 = {New York, Chicago and
Dallas}. If one VSI per PE is set up to interconnect these four
sites. BUM traffic of Atlanta site will be poured to Dallas site, and
vice versa.
When PEs are aware of the U-tag, the BUM traffic can be confined per
BD with multicast pruning. For above example, the operator need use
two U-tags to distinguish the two BDs. In this way, BUM traffic of
Atlanta site will be confined in BD1 and BUM traffic for Dallas site
will be confined in BD2. This increases the efficiency of the
bandwidth utilization of BUM traffic.
Two C-VLAN based multicast pruning techniques are listed below. (One
is give in [V-aware] the other has been implemented by vendors.)
4.3.1. Advertising Interested VLANs in LDP
With the PW VLAN Vector TLV defined in [V-aware], PEs can advertise
in LDP the interested C-VLANs for its interfaces. In this way, PEs
can prune the flooding on a per C-VLAN basis.
4.3.2. Dynamic VLAN Registration with MVRP
It requires Multiple VLAN Registration Protocol (MVRP) to be
supported by PEs for U-tag registration on the interfaces providing
VPLS. With the help of MVRP, operators need not manually configure C-
VLANs on PEs.
Mingui Zhang, et al Expires February 13, 2015 [Page 5]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
Only when a C-VLAN is registered in both directions of a PW, this PW
will not be eliminated for this C-VLAN. Otherwise, this PW will be
pruned for this C-VLAN. Multicast frames for a C-VLAN SHOULD only be
forwarded on PWs that are not pruned for this C-VLAN.
4.4. Per C-VLAN MAC Withdraw
With the awareness of U-tag, PEs can achieve a finer gained C-VLAN
scoped MAC withdraw. For example, with the VLAN Vector TLV defined in
[V-aware], a PE can specify VLANs that it wants their MAC address to
be flushed.
5. Backward Compatibility
Two PEs need negotiate their capability on supporting the awareness
of U-tag. Unless both PEs are aware of U-tag, the tagged PW cannot be
established. When a PE realizes the peering PE's interface is unaware
of U-tag, it MUST fall back to establish a raw PW with this
interface.
There are two ways to achieve the capability negotiation.
a) As defined in Section 4 of [V-aware], PEs can negotiate this
capability through LDP using the VLAN Aware Capability TLV.
b) A tagged PW is established between two interfaces if they both
enable MVRP.
For the tagged PW, PEs can achieve customer VLAN scoped MAC address
flushing [V-aware]. However, PEs may as well send out the old type
MAC withdraw message per Section 6.2 of [RFC4762]. The receiver PE
parses this kind of message as that the peering PE is flushing MAC
addresses across all customer VLANs supported by this PW.
6. Contributors
Xingjian He, Huawei
7. Security Considerations
This document raises no new security issues. For general security
considerations, refer to [RFC4761] and [RFC4762].
8. IANA Considerations
This document requires no IANA actions. RFC Editor: please remove
this section before publication.
Mingui Zhang, et al Expires February 13, 2015 [Page 6]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
9. References
9.1. Normative References
[V-aware] D. Cai, S. Boutros, and et al, "VLAN Aware VPLS services",
draft-cai-l2vpn-vpls-vlan-aware-bundling-00.txt, working in
progress.
[MVRP] IEEE P802.1ak/D8.0, "IEEE Standard for Local and
Metropolitan Area Networks: Virtual Bridged Local Area
Networks -- Amendment 07: Multiple Registration Protocol",
November 29, 2006.
[RFC4762] Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, January 2007.
9.2. Informative References
[RFC4761] Kompella, K., Ed., and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, January 2007.
Mingui Zhang, et al Expires February 13, 2015 [Page 7]
INTERNET-DRAFT To Recognize U-tag in VPLS August 12, 2014
Author's Addresses
Mingui Zhang
Huawei Technologies
No. 156 Beiqing Rd. Haidian District,
Beijing 100095
P.R. China
EMail: zhangmingui@huawei.com
Bin Wang
Huawei Technologies
No. 156 Beiqing Rd. Haidian District,
Beijing 100095
P.R. China
EMail: zhangmingui@huawei.com
Liang Xia
Huawei Technologies
Email: frank.xialiang@huawei.com
Jie Hu
China Telecom
Email: hujie@ctbri.com.cn
Mingui Zhang, et al Expires February 13, 2015 [Page 8]
