Internet DRAFT - draft-hao-l3vpn-inter-nvo3-vpn
draft-hao-l3vpn-inter-nvo3-vpn
L3VPN Weiguo Hao
Lucy Yong
S. Hares
Internet Draft Huawei
R. Raszuk
L. Fang
Microsoft
Shahram Davari
Broadcom
Intended status: Informational September 17, 2014
Expires: March 2015
Inter-AS Option B between NVO3 and BGP/MPLS IP VPN network
draft-hao-l3vpn-inter-nvo3-vpn-01.txt
Abstract
This draft describes the solution of inter-as option-B connection
between NVO3 network and MPLS/IP VPN network. The ASBR located in
NVO3 network is called ASBR-d, the control plane and data plane
procedures at ASBR-d are specified in this document, they are
different from traditional option-B ASBR defined in [RFC 4364].
Status of this Memo
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This Internet-Draft will expire on March 17, 2015.
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Table of Contents
1. Introduction ................................................ 2
2. Conventions used in this document............................ 3
3. Reference model ............................................. 4
4. Option-A inter-as solution overview.......................... 5
5. Option-B inter-as solution overview.......................... 5
6. Inter-As Option-B procedures................................. 6
6.1. Using RFC 4364 ......................................... 6
6.1.1. DC to WAN direction................................ 6
6.1.2. WAN to DC direction................................ 7
6.2. NVE-NVA architecture.................................... 8
6.2.1. DC to WAN direction................................ 8
6.2.2. WAN to DC direction................................ 8
7. Enhanced Option-B solution................................... 9
8. Security Considerations...................................... 9
9. IANA Considerations ......................................... 9
10. References ................................................. 9
10.1. Normative References................................... 9
10.2. Informative References................................ 10
11. Acknowledgments ........................................... 10
1. Introduction
In cloud computing era, multi-tenancy has become a core requirement
for data centers. Since NVO3 can satisfy multi-tenancy key
requirements, this technology is being deployed in an increasing
number of cloud data center network. NVO3 focuses on the
construction of overlay networks that operate over an IP (L3)
underlay transport network. It can provide layer 2 bridging and
layer 3 IP service for each tenant. VXLAN and NVGRE are two typical
NVO3 technologies. NVO3 overlay network can be controlled through
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centralized NVE-NVA architecture or through distributed BGP VPN
protocol.
NVO3 has good scaling properties from relatively small networks to
networks with several million tenant systems (TSs) and hundreds of
thousands of virtual networks within a single administrative domain.
In NVO3 network, 24-bit VN ID is used to identify different virtual
networks, theoretically 16M virtual networks can be supported in a
data center. In a data center network, each tenant may include one
or more layer 2 virtual network and in normal cases each tenant
corresponds to one routing domain (RD). Normally each layer 2
virtual network corresponds to one or more subnets.
To provide cloud service to external data center client, data center
networks should be connected with WAN networks. BGP MPLS/IP VPN has
already been widely deployed at WAN networks. Normally internal data
center and external MPLS/IP VPN network belongs to different
autonomous system(AS). This requires the setting up of inter-as
connections at Autonomous System Border Routers(ASBRs) between NVO3
network and external MPLS/IP network.
Currently, a typical connection mechanism between a data center
network and an MPLS/IP VPN network is similar to Inter-AS Option-A
of RFC4364, but it has scalability issue if there is huge number of
tenants in data center networks. To overcome the issue, inter-as
Option-B between NVO3 network and BGP MPLS/IP VPN network is
proposed in this draft.
2. Conventions used in this document
Network Virtualization Edge (NVE) - An NVE is the network entity that
sits at the edge of an underlay network and implements network
virtualization functions.
Tenant System - A physical or virtual system that can play the role
of a host, or a forwarding element such as a router, switch,
firewall, etc. It belongs to a single tenant and connects to one or
more VNs of that tenant.
VN - A VN is a logical abstraction of a physical network that
provides L2 network services to a set of Tenant Systems.
RD - Route Distinguisher. RDs are used to maintain uniqueness among
identical routes in different VRFs, The route distinguisher is an 8-
octet field prefixed to the customer's IP address. The resulting 12-
octet field is a unique "VPN-IPv4" address.
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RT - Route targets. It is used to control the import and export of
routes between different VRFs.
3. Reference model
+---------------------------------------------------+
| +----+ AS1 |
| | TS1| - |
| +----+ - |
| - +----+ +----+ |
| - |NVE1| -- |TOR1|---------------+ |
| +----+ - +----+ +----+ | |
| | TS2|- | |
| +----+ | |
| +-------+ |
| +------------ | ASBR-d| |
| +----+ | +-------+ |
| | TS3| - | | |
| +----+ - | | |
| - +----+ +----+ | |
| - |NVE2| -- |TOR2| | |
| +----+ - +----+ +----+ | |
| | TS4|- | |
| +----+ | |
|----------------------------------------------------
| | |
| +----+ | |
| | CE1| - | |
| +----+ - | |
| - +----+ +-------+ |
| - | PE1| --------------------| ASBR-w| |
| +----+ - +----+ +-------+ |
| | CE2|- |
| +----+ AS2 |
|---------------------------------------------------|
Figure 1 Reference model
Figure 1 shows an arbitrary Multi-AS VPN interconnectivity scenario
between NVO3 network and BGP MPLS/IP VPN network. NVE1, NVE2, and
ASBR-d forms NVO3 overlay network in internal DC. TS1 and TS2
connect to NVE1, TS3 and TS4 connect to NVE2. PE1 and ASBR-w forms
MPLS IP/VPN network in external DC. CE1 and CE2 connect to PE1. The
NVO3 network belongs to AS 1, the MPLS/IP VPN network belongs to AS
2.
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There are two tenants in NVO3 network, TSs in tenant 1 can freely
communicate with CEs in VPN-Red, TSs in tenant 2 can freely
communicate with CEs in VPN-Green. TS1 and TS3 belong to tenant 1,
TS2 and TS4 belong to tenant 2. CE1 belongs to VPN-Red , CE2 belongs
to VPN-Green. VN ID 10 and VN ID 20 are used to identify tenant1 and
tenant2 respectively.
4. Option-A inter-as solution overview
In Option-A inter-as solution, peering ASBRs are connected by
multiple sub-interfaces, each ASBR acts as a PE, and thinks that the
other ASBR is a CE. Virtual routing and forwarding (VRF)data bases
(RIB/FIB) are configured at AS border routers (ASBR-d and ASBR-w) so
that each ASBRs associate each such sub-interface with a VRF and use
EBGP to distribute unlabeled IPv4 addresses to each other. In the
data-plane, VLANs are used for tenant traffic separation. ASBR-d
terminates NVO3 encapsulation for inter-subnet traffic from TS in
internal DC to CE in external DC.
Option-A inter-as solution has following issues:
1. Up to 16 million (16M) gateway interfaces (virtual/physical) and
16M EBGP session need to exist between the ASBRs.
2. UP to 16M VRFs need to be supported on border routers.
3. Several million routing entries need to be supported on border
routers.
Inter-as option B between NVO3 network and MPLS IP/VPN network can
be used to address these issues. Because it is for multi-as
interconnection between heterogeneous networks, so there are some
differences from traditional Inter-AS Option-B of RFC4364.
5. Option-B inter-as solution overview
Similar to the solution described in section 10, part (b) of
[RFC4364] (commonly referred to as Option-B) peering ASBRs are
connected by one or more sub-interfaces that are enabled to receive
MPLS traffic. An MP-BGP session is used to distribute the labeled
VPN prefixes between the ASBRs. In data plane, the traffic that
flows between the ASBRs is placed upon MPLS tunnels, traffic
separation among different VPNs between the ASBRs relies on MPLS VPN
Label. The advantage of this option is that it's more scalable, as
there is no need to have one sub-interface and BGP session per
VPN/Tenant.
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As for the routing distribution process from DC to WAN side, MPLS
VPN Label is allocated on ASBR-d per VN per NVE. As for the routing
distribution process from WAN to DC side, VN ID is allocated per
MPLS VPN Label receiving from ASBR-w on ASBR-d. From data plane
perspective, VN ID and MPLS VPN Label switching is performed on
ASBR-d, ASBR-w has no difference with traditional RFC4364 based
Option-B behavior, no VRF is created on the ASBR-d.
6. Inter-As Option-B procedures
Each NVE operates as default layer 3 gateway for local connecting
TS(s). VRFs are created on each NVE to isolate IP forwarding process
between different tenants. At least a L3 VN ID is used to identify
each tenant.
Routing data for each tenant should be synchronized between NVO3 and
MPLS VPN network. In internal DC NVO3 network, routing data
synchronization between NVE and ASBR-d can be through either: a) RFC
4364 running between the NVEs and the ASBR1, or b) NVE-NVA
architecture.
The Data plane process is same in these two cases.
6.1. Using RFC 4364
Route distinguishers (RD) and RT are specified for each VRF on each
NVE. BGP MPLS/IP VPN protocol extension is running between NVEs and
ASBR-d utilizing the [BGP Remote-Next-Hop] which describes the BGP
MPLS/IP VPN protocol extension details to specify a set of remote
tunnels (1 to N) that occur between two BGP speakers.
6.1.1. DC to WAN direction
1. NVE1 and NVE2 advertise local TS's IP Address to ASBR-d. NVE1 and
NVE2 learn the local TS's IP Address via ARP or other mode.
2. When ASBR-d receives route data from each NVE, it allocates MPLS
VPN Label per tenant (VN ID) per NVE and the RD and RT remain the
same. Then the ASBR-d advertises the VPN route with new allocated
MPLS VPN Label to ASBR-w. The allocated MPLS VPN label and its
corresponding <NVE, VN ID> pair forms incoming forwarding table
which is used to forward MPLS traffic from external DC to
internal DC. The incoming forwarding table on ASBR-d is as
follows:
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+--------------------+------------------+
| MPLS VPN Label | NVE + VN ID |
+--------------------+------------------+
| 1000 | NVE1 + 10 |
+--------------------+------------------+
| 2000 | NVE1 + 20 |
+--------------------+------------------+
| 1001 | NVE2 + 10 |
+--------------------+------------------+
| 2001 | NVE2 + 20 |
+--------------------+------------------+
Incoming forwarding table
6.1.2. WAN to DC direction
1. When ASBR-d receives route data from ASBR-w, ASBR-d allocates VN
ID for each VPN Label, and then ASBR-w advertises the VPN route
with new allocated VN ID to each NVE (NVE1 and NVE2). The role of
the VN ID is similar to the role of Incoming VPN Label in vanilla
ASBR, it has local significance on ASBR-d, each VN ID corresponds
to a MPLS VPN Label on peer ASBR-w; The VN ID space should be
assigned in beforehand and should be orthogonal to the VN ID
space for tenant identification(for example, assuming ASBR-d has
local connecting TSs of tenant 1 to tenant 100, VN ID 1 to 100
are allocated for these tenants, other VN ID other than 1 to 100
can be allocated for outgoing forwarding table purpose). The
allocated VN ID and its corresponding out VPN Label forms an
outgoing forwarding table which is used to forward NVO3 traffic
from internal DC to external DC. Assuming ASBR-d receives VPN
Label 3000 and 4000 from ASBR-w, the outgoing forwarding table on
ASBR-d is as follows:
+------------------+--------------------+
| VN ID | Out VPN Label |
+------------------+--------------------+
| 10000 | 3000 |
+------------------+--------------------+
| 10001 | 4000 |
+------------------+--------------------+
Outgoing forwarding table
2. When each local NVE receives route data from ASBR-d, it matches
the Route Target Attribute in BGP MPLS/IP VPN protocol with local
VRF's import RT configuration and populates local VRF with these
matched VPN routes.
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6.2. NVE-NVA architecture
No distributed BGP VPN protocol (RFC4364) is running on all NVEs and
ASBR-d in NVO3 network, NVEs and ASBR-d are controlled by
centralized NVA. The NVA runs EBGP VPN protocol with peer ASBR-w and
exchanges VPN routing information between NVO3 network and MPLS/IP
VPN network.
NVA maintains tenant information collected from all tenants. This
information includes VN ID to identify each tenant and the
corresponding RD and RT. This information can be statically
configured by operators or dynamically notified by cloud management
systems.
NVA also maintains all TS's MAC/IP address and its attached NVE
information for each tenant.
------ EBGP --------
|NVA | ------------- |ASBR2 |
------ --------
.
. Southbound interface(Openflow,OVSDB,etc)
........................
. . .
. . .
. . .
------ ------ -------
|NVE1| |NVE2| |ASBR1|
------ ------ -------
Figure 2 NVE-NVA Architecture
6.2.1. DC to WAN direction
1. NVA allocates MPLS VPN Label per tenant per NVE.
2. NVA advertises all internal data center VPN routing information
to peer ASBR-w, which includes RD, IP prefix, RT, and MPLS VPN
Label.
3. NVA downloads incoming forwarding table to ASBR-d.
6.2.2. WAN to DC direction
1. NVA receives VPN routing information from peer ASBR-w.
2. NVA allocates VN ID for each MPLS VPN Label receiving from ASBR-w.
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3. NVA downloads outgoing forwarding table to ASBR-d.
4. NVA matches local Route Target configuration, imports VPN route
to each tenant, and downloads routing table to corresponding NVE.
7. Enhanced Option-B solution
At WAN network side, if there is a VPN with multiple IP prefixs, VPN
route synchronization to local NVE located in data center network
will cause a lot pressure on it. In this case, the procedures above
at ASBR-d can be enhanced as follows.
EBGP VPN connection for this VPN is terminated at ASBR-d, which
means the ASBR doesn't allocate new VN ID for each MPLS VPN Label
and advertise it to peer NVE in local AS, VRF is created on the
ASBR-d, the VPN route from WAN side populates to local VRF. For the
traffic from DC to WAN side, IP forwarding process is performed, VRF
is selected based on VN ID, and then the traffic will be MPLS
encapsulated and send to peer ASBR-w.
8. Security Considerations
Similar to the security considerations for inter-as Option-B in
[RFC4364] the appropriate trust relationship must exist between NVO3
network and MPLS/IP VPN network. VPN-IPv4 routes in NVO3 network
should neither be distributed to nor accepted from the public
Internet, or from any BGP peers that are not trusted. For other
general VPN Security Considerations, see [RFC4364].
9. IANA Considerations
This document requires no IANA actions. RFC Editor: Please remove
this section before publication.
10. References
10.1. Normative References
[1] [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[2] [RFC4364] E. Rosen, Y. Rekhter, " BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
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10.2. Informative References
[1] [NVA] D.Black, etc, "An Architecture for Overlay Networks
(NVO3)", draft-ietf-nvo3-arch-01, February 14, 2014
[2] [BGP Remote-Next-Hop] G. Van de Velde,etc, ''BGP Remote-Next-Hop'',
draft-vandevelde-idr-remote-next-hop-05, January, 2014
[3] [RFC7047] B. Pfaff, B. Davie,''The Open vSwitch Database
Management Protocol'', RFC 7047, December 2013
[4] [OpenFlow1.3]OpenFlow Switch Specification Version 1.3.0 (Wire
Protocol 0x04). June 25, 2012.
(https://www.opennetworking.org/images/stories/downloads/sdn-
resources/onf-specifications/openflow/openflow-spec-v1.3.0.pdf)
11. Acknowledgments
Authors like to thank Xiaohu Xu, Liang Xia, Shunwan Zhang, Yizhou Li
for his valuable inputs.
Authors' Addresses
Weiguo Hao
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Email: haoweiguo@huawei.com
Lucy Yong
Huawei Technologies
Phone: +1-918-808-1918
Email: lucy.yong@huawei.com
Susan Hares
Huawei Technologies
Phone: +1-734-604-0323
Email: shares@ndzh.com.
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Robert Raszuk
Email: robert@raszuk.net
Luyuan Fang
Microsoft
Email: lufang@microsoft.com
Shahram Davari
Broadcom
Davari@Broadcom.com
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