BGP Extension For L3VPN
Performance MonitoringHuaweiHuawei Bld., No.156 Beiqing Rd.Beijing100095Chinafanjiajia@huawei.comHuaweiHuawei Bld., No.156 Beiqing Rd.Beijing100095Chinalizhenbin@huawei.comHuaweiHuawei Bld., No.156 Beiqing Rd.Beijing100095Chinazhuangshunwan@huawei.comThis document describes a new VT address family in BGP to exchange
information required for apply performance monitoring in MPLS/BGP VPN,
as described in .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.This document describes the BGP encodings and procedures for
exchanging the information elements required by applying traffic
performance monitoring in MPLS/BGP VPN, as specified in.Current BGP Labeled VPN Route exchange procedure combines VRF VPN-
membership Auto-Discovery and L3VPN Label allocation together. While
applying PM for L3VPN needs BGP extended to support VPN membership
Auto-Discovery and L3VPN Label allocation in a VRF-to-VRF manner. To
achieve this, a new Sub address family, called VRF-to-VRF Tunnel(VT)
Subsequent Address Family, is introduced.This document defines two kinds of routes for VT NLRI:VPN-Membership A-D Route: for the use of doing VRF VPN membership
auto-discovery in VRF-to-VRF mannerVT Labeled Route: for the use of allocating VT Label from Local VRF
to Remote VRF to setup VRF-to-VRF Tunnel between the pair of VRFs.This document uses the terminologies defined in [RFC4026]:ERT: Export Route TargetIRT: Import Route TargetPE: Provider EdgeRD: Route DistinguisherVRF: Virtual Routing and ForwardingVT: VRF-to-VRF TunnelThe BGP Multiprotocol Extensions allow BGP
to carry routes from multiple "address families". In this document a new
Subsequent Address Family is introduced, called "VT Sub Address
Family".VT Address Family uses AFI 1/2 to present IPv4/IPv6 Address Family
and a specific VT_SAFI(TBD) to present VT Subsequent Address
Family.VT MP_REACH_NLRI and MP_UNREACH_NLRI are formatted as described in
[RFC4760]BGP VT NLRI has format as depicted in following diagram:Route Type indicates type of route under VT SAFI.Type 1: VT VPN membership A-D RouteType 2: VT Labeled RouteLength defines Route Type specific routes length in octetsRoute Type specific route information field, encoded according to
Route Type definition.VT VPN membership A-D Route, concisely named as VT A-D Route
hereafter, is utilized for VRF-to-VRF VPN Membership Auto-Discovery
between PEs.Its format is defined as following diagram:a) RD: RD of one VRF on advertising PE, encoded as
described in [RFC4364].b) Local Router's IP Address: Advertising PE's IPv4/IPv6 address
<RD, Local Router's IP Address> is defined as Prefix of VT A-D
Route.VT Labeled Route is utilized for VRF-To-VRF Label(s) allocation
and advertisement, its format is defined as following diagram.a) Local RD: Route Distinguisher value of one VRF on
advertising PE, encoded as described in [RFC4364].b) Local Router's IP Address: Advertising PE's IPv4/IPv6
address.c) Remote VRF's RD: Route Distinguisher value of Remote VRF
encoded as described in [RFC4364].d) Remote Router's IP Address: Remote PE's IPv4/IPv6 address.e) Label: The Label field carries one or more labels that
corresponds to the stack of labels . Each
label is encoded as 3 octets, where the high-order 20 bits contain
the label value, and the low- order bit contains "Bottom of Stack"
as defined in .<Local RD, Local Router's IP Address, Remote VRF's RD, Remote
Router's IP Address> which indicates a pair of VRFs is defined as
the Prefix of VT Labeled Route.For every PE, it needs to process all its VRF configured and
generate one VT A-D Route for each VRF respectively.RD field MUST be filled with the VRF's RD value.Local Router's IP Address field MUST filled with the Advertising
Router's IP address.The VT A-D Route MUST carry all IRTs of the VRF in BGP Update's
Ext- Community Path Attribute, route importing request of one VRF is
described by its corresponding VT A-D route. In contrast VPN Labeled
Routes carry ERTs in BGP Update's Ext-Community Path Attribute.If a VRF is created, then its corresponding VT A-D Route MUST be
generated and advertised.If the VRF whose VT A-D Route has been advertised is deleted, then
the VT A-D Route Withdrawal message MUST be generated and
advertised.If IRT of the VRF whose VT A-D Route has been advertised is
changed, then a VT A-D Route Update with same Prefix and latest IRTs
MUST be advertised.When receiving PE receives VT A-D Route, VPN relationship matching
MUST be checked between IRTs in VT A-D Route and ERTs of each Local
VRF, this process is called VRF-to-VRF VPN membership Auto
Discovery.Either finding one VRF-to-VRF VPN membership newly formed or
released, receiving PE MUST proceed to the VT Labeled Route processing
described in next section.If Receiving PE finds one new VRF-to-VRF VPN membership formed,
it MUST allocate one VT MPLS Label for the VRF-to-VRF VPN membership
and the label is advertised to the Remote VRF by VT Labeled
Route.Local RD MUST filled with RD value of the Local VRF which is
found belong to the same VPN with Remote VRF.Local Router's IP Address Must filled with the advertising PE's
IPv4/ IPv6 address.Remote VRF's RD MUST filled with RD value of the Remote VRF which
belongs to a same VPN with the Local VRF.Remote Router's IP Address: Remote PE's IPv4/IPv6 address.Label: MUST be filled with one or more MPLS Labels allocated by
advertising PE for the pair of VRFs.Only both sides of a pair of VRFs learnt each other's VT Labeled
Route advertisement, the VRF-to-VRF tunnel between the pair of VRFs
is considered setup.If receiving PE finds one existing VRF-to-VRF VPN membership
released then it MUST send out the VT Labeled Route Withdrawal
message, then release the MPLS Label(s) allocated.Local RD MUST be filled with RD value of the Local VRF.Local Router's IP Address MUST be filled with the advertising
PE's IPv4/IPv6 address.Remote VRF's RD MUST be filled with RD value of the Remote
VRF.Remote Router's IP Address: MUST be filled with Remote PE's
IPv4/IPv6 address.Label: MUST be filled with ZERO or the MPLS Labels value
allocated for the VT Labeled Route.To achieve the goal of converting normal L3VPN MP2P forwarding
model into P2P model which is required in , after VPNv4 routes received,
Receiving PE MUST apply VT Labels when downloading VPNv4 Route into
Data Plan which is in detail described in .Between a pair of PEs both support VT capability, It COULD be an
implementation option that VPNv4 Routes from a remote VRF WOULD NOT be
downloaded into a Local VRF's Forwarding Plan until a VT Labeled route
received from same Remote VRF for the Local VRF.If VT Labeled Route withdrawal message is received, receiving PE
MUST delete VT Labels from Forwarding Plane and VPNv4 Routes MUST be
kept on Forwarding Plane with original VPNv4 Label as inner Label.When receiving and processing VT A-D Route, the BGP best route
selection procedure described in MUST be
followed.When receiving and processing VT Labeled Route, the BGP best route
selection procedure described in COULD be
followed.Especially VT Labeled Route MUST be advertised ONLY to the BGP peer
from which the best VT A-D route is received, the VT A-D route contains
the Remote VRF's RD and Remote PE's IP address.If a Peer receives VT A-D or VT Labeled Route originated from itself,
the route MUST be ignored.This document currently supports deploying VT SAFI in following two
manners:a) Inner-AS L3VPN with Full-mesh IBGP sessions or Router
Reflectors.b)Inter-AS L3VPN with Option A(VRF-to-VRF)[RFC4364].How to support Inter-AS L3VPN Option B(MP-EBGP) and Option-C will be described in this draft's future version.A new SAFI value to present VT Subsequent Address Family is required
and to be allocated by IANA.This extension to BGP does not change the underlying security
issues.TBD.