Internet DRAFT - draft-abhattacharya-bess-l2vpn-ipv6-remotepe
draft-abhattacharya-bess-l2vpn-ipv6-remotepe
INTERNET-DRAFT Avik Bhattacharya
Updates: 6074 (if approved) Apratim Mukherjee
Intended Status: Standards Track Ixia
Expires: August 23, 2015 February 19, 2015
Provisioning, Auto-Discovery, and Signaling in L2VPNs for IPv6 Remote PE
draft-abhattacharya-bess-l2vpn-ipv6-remotepe-03
Abstract
L2VPN Signaling specification defines the semantic structure of the
endpoint identifiers required by each model. It discusses the
distribution of these identifiers by the discovery process,
especially when such discovery is based on the Border Gateway
Protocol (BGP). This document updates the end point encoding for
BGP-Based Auto-Discovery and specifies a format for NLRI encoding for
IPv6 PE Address. This document also specifies a new type of
attachment identifier to carry IPv6 address as AII in LDP FEC 0x81.
This document updates RFC6074.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Copyright and License Notice
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. This document may contain
material from IETF Documents or IETF Contributions published or made
publicly available before November 10, 2008. The person(s)
controlling the copyright in some of this material may not have
granted the IETF Trust the right to allow modifications of such
material outside the IETF Standards Process. Without obtaining an
adequate license from the person(s) controlling the copyright in such
materials, this document may not be modified outside the IETF
Standards Process, and derivative works of it may not be created
outside the IETF Standards Process, except to format it for
publication as an RFC or to translate it into languages other than
English.
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2 BGP NLRI Format for the IPv6 PE Address . . . . . . . . . . . . 4
3 Discussion on Route Distinguisher (RD) and Route Target (RT) . 5
4 Using IPv6 Remote PE address for signaling using LDP . . . . . 5
5 Interoperability in a mixed IPv4/IPv6 Network . . . . . . . . . 6
6 Security Considerations . . . . . . . . . . . . . . . . . . . . 6
7 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1 Normative References . . . . . . . . . . . . . . . . . . . 7
9.2 Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1 Introduction
[RFC6074] specifies a number of L2VPN provisioning models, and
further specifies the semantic structure of the endpoint identifiers
required by each model. It discusses the distribution of these
identifiers by the discovery process, especially when discovery is
based on the Border Gateway Protocol (BGP). It then specifies how
the endpoint identifiers are carried in the two signaling protocols
that are used to set up PWs, the Label Distribution Protocol (LDP),
and the Layer 2 Tunneling Protocol version 3 (L2TPv3) [RFC6074].
This document updates Section 3.2.2.1 of RFC 6074 (BGP-Based Auto-
Discovery) and specifies a format for NLRI encoding that allows to
carry also an IPv6 PE Address.This document also specifies a new type
of attachment identifier to carry IPv6 address as AII in LDP FEC
0x81. This gap in the specification of L2VPN in IPv6 only MPLS
Network is also recognized in section 3.3.1 of [RFC7439].
1.1 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].
2 BGP NLRI Format for the IPv6 PE Address
Section 3.2.2.1 of [RFC6074] specifies the BGP advertisement for a
particular VSI at a given PE will contain:
o an NLRI of AFI = L2VPN, SAFI = VPLS, encoded as RD:PE_addr
o a BGP next hop equal to the loopback address of the PE
o an Extended Community Attribute containing the VPLS-id
o an Extended Community Attribute containing one or more RTs.
The format for the NLRI encoding defined in Section 3.2.2.1 of
[RFC6074] is:
+------------------------------------+
| Length (2 octets) |
+------------------------------------+
| Route Distinguisher (8 octets) |
+------------------------------------+
| PE_addr (4 octets) |
+------------------------------------+
Figure 1: NLRI encoding in [RFC6074]
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In this format the size of the PE_addr is defined as 4 octets which
can carry only IPv4 addresses. In a situation where the route is
originating from a BGP end point running on an IPv6 address, the
PE_addr in the NLRI needs to carry that IPv6 address. The updated
format for the NLRI encoding is depicted in Figure 2.
+------------------------------------+
| Length (2 octets) |
+------------------------------------+
| Route Distinguisher (8 octets) |
+------------------------------------+
| PE_addr (4 or 16 octets) |
+------------------------------------+
Figure 2: Updated NLRI encoding
The length field MUST contain the sum of the length of the Length
field(2), the length of the Route Distinguisher (8) and the length of
the 4 or 16 octet PE_addr field.
The type of the PE_addr can be derived by the receiving node by
subtracting the fixed length of the Route Distinguisher and the
Length field from the value of the received Length. An IPv4 PE_addr
should be used to initiate adjacency of the underlying signaling
protocol if it supports IPv4. An IPv6 PE_addr should be used to
initiate adjacency of the underlying signaling protocol if it
supports IPv6. (such as LDPv6)
3 Discussion on Route Distinguisher (RD) and Route Target (RT)
Note that RD and RT can be in format AS 2byte + 4 byte Assigned
Number or IP 4 byte + 2 byte Assigned Number [RFC4364]. Just like RD
or RT cannot carry 4 byte AS numbers , they also cannot utilize 16
byte IPv6 Address. Updates to RD and RT to operate in a pure IPv6
environment is outside the scope of this document.
4 Using IPv6 Remote PE address for signaling using LDP
Section 5.3.2 of [RFC4447] specifies the format of encoding for
Generalized ID FEC Element (FEC 0x81)which is used for signaling in
LDP. This document specifies a new type for AII carrying IPv6 address
as TAII or SAII. (See Section 7)
An FEC 0x81 TLV MUST contain SAII and TAII of the same type i.e.
either type 1 or type 2.
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5 Interoperability in a mixed IPv4/IPv6 Network
If a VPLS instance is reachable though both IPv4 and IPv6 loopback in
a PE node then the BGP instance(s) of that PE node MUST advertise the
VPLS route using both NLRIs - one with IPv4 PE_addr and another with
IPv6 PE_addr.
While signaling a TAII in type 2 format, the LDP implementation MUST
use SAII also in type 2 format. The value of the SAII MAY be set from
the IPv6 loopback address on which the BGP session is established.
While signaling a TAII type over an LDP session, on which it has
already signaled with the other TAII type but with the same AGI, it
SHOULD use the same label value in the Label Mapping for both TAII
types.
On receiving an FEC 0x81 TLV in a Label Advertisement with a TAII
type, the LDP implementation MAY lookup if on the same LDP session it
has received a Label Mapping with the other TAII type but for the
same AGI. If yes then it MUST store the Label Mapping but MAY choose
not to install the label. If it chooses not to do the lookup stated
above then it MUST install the received label.
If the LDP implementation chooses to do the lookup stated above
during receipt of the Label Mapping, on receiving an FEC 0x81 TLV in
a Label Withdraw with a TAII type, the LDP implementation MUST lookup
if on the same LDP session it has received another Label Mapping with
other TAII type but same AGI. If yes then it MUST install the stored
Label Mapping and keep using that thereafter. ( Along with taking
necessary actions for processing the Label Withdraw as specified in
[RFC5036])
6 Security Considerations
There is no additional security impact in addition to what is
mentioned in [RFC6074].
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7 IANA Considerations
This document requires a new AII type to be used in Generalized ID
FEC (0x81). IANA already maintains a registry of name "Attachment
Individual Identifier(AII) Type" specified by [RFC4446].
The following value is suggested for assignment:
AII Type Length Description
===================================================================
0x02 16 A 128 bit unsigned number local identifier.
8. Acknowledgments
Thanks to Mohamed Boucadair for his valuable suggestions.
9 References
9.1 Normative References
[RFC2119] S. Bradner,"Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6074] E. Rosen, B. Davie, "Provisioning, Auto-Discovery, and
Signaling in Layer 2 Virtual Private Networks (L2VPNs)",
BCP 74, RFC 6074, January 2011,
<http://www.rfc-editor.org/info/rfc6074>.
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446, April 2006,
<http://www.rfc-editor.org/info/rfc4446>.
[RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G.
Heron, "Pseudowire Setup and Maintenance Using the Label
Distribution Protocol (LDP)", RFC 4447, April 2006,
<http://www.rfc-editor.org/info/rfc4447>.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October
2007,<http://www.rfc-editor.org/info/rfc5036>.
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[RFC7439] W. George, C. Pignataro,, "Gap Analysis for Operating
IPv6-Only MPLS Networks", RFC 7439, January
2015,<http://www.rfc-editor.org/info/rfc7439>.
9.2 Informative References
[RFC4364] E. Rosen, "BGP/MPLS IP Virtual Private Networks (VPNs)",
BCP 78, RFC 4364, February 2006,
<http://www.rfc-editor.org/info/rfc4364>.
Authors' Addresses
Avik Bhattacharya
Ixia
Infinity Building, Tower 2, Floor -4
Sector 5, Saltlake,
Kolkata, West Bengal, India - 700091.
EMail: abhattacharya@ixiacom.com
Apratim Mukherjee
Ixia
Infinity Building, Tower 2, Floor -4
Sector 5, Saltlake,
Kolkata, West Bengal, India - 700091.
EMail: amukherjee@ixiacom.com
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