draft-ietf-bess-virtual-subnet-fib-reduction-02.txt   draft-ietf-bess-virtual-subnet-fib-reduction-03.txt 
Network Working Group X. Xu Network Working Group X. Xu
Internet-Draft Huawei Internet-Draft Huawei
Intended status: Informational C. Jacquenet Intended status: Informational C. Jacquenet
Expires: September 1, 2016 Orange Expires: February 4, 2017 Orange
T. Boyes T. Boyes
Bloomberg LP Bloomberg LP
B. Fee B. Fee
Extreme Networks Extreme Networks
W. Henderickx W. Henderickx
Alcatel-Lucent Alcatel-Lucent
February 29, 2016 August 3, 2016
FIB Reduction in Virtual Subnet FIB Reduction in Virtual Subnet
draft-ietf-bess-virtual-subnet-fib-reduction-02 draft-ietf-bess-virtual-subnet-fib-reduction-03
Abstract Abstract
Virtual Subnet is a BGP/MPLS IP VPN-based subnet extension solution Virtual Subnet is a BGP/MPLS IP VPN-based subnet extension solution
which is intended for building Layer3 network virtualization overlays which is intended for building Layer3 network virtualization overlays
within and/or between data centers. This document describes a within and/or between data centers. This document describes a
mechanism for reducing the FIB size of PE routers in the Virtual mechanism for reducing the FIB size of PE routers in the Virtual
Subnet context. Subnet context.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 1, 2016. This Internet-Draft will expire on February 4, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Solution Description . . . . . . . . . . . . . . . . . . . . 3 3. Solution Description . . . . . . . . . . . . . . . . . . . . 3
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
Virtual Subnet [I-D.ietf-bess-virtual-subnet] is a BGP/MPLS IP VPN Virtual Subnet [RFC7814] is a BGP/MPLS IP VPN [RFC4364] -based subnet
[RFC4364] -based subnet extension solution which is intended for extension solution which is intended for building Layer3 network
building Layer3 network virtualization overlays within and/or across virtualization overlays within and/or across data centers. In the
data centers. In the Virtual Subnet context, since CE host routes of Virtual Subnet context, since CE host routes of a given VPN instance
a given VPN instance need to be exchanged among PE routers need to be exchanged among PE routers participating in that VPN
participating in that VPN instance, the resulting forwarding table instance, the resulting forwarding table (a.k.a. FIB) size of PE
(a.k.a. FIB) size of PE routers may become a big concern in large- routers may become a big concern in large-scale data center
scale data center environment where they may need to install a huge environment where they may need to install a huge amount of host
amount of host routes into their forwarding tables. In some cases routes into their forwarding tables. In some cases where host routes
where host routes need to be maintained on the control plane, it need to be maintained on the control plane, it needs a method to
needs a method to reduce the FIB size of PE routers without any reduce the FIB size of PE routers without any change to the RIB and
change to the RIB and the routing table. Therefore, this document the routing table. Therefore, this document proposes a very simple
proposes a very simple mechanism for reducing the FIB size of PE mechanism for reducing the FIB size of PE routers. The basic idea of
routers. The basic idea of this mechanism is: Those host routes this mechanism is: Those host routes learnt from remote PE routers
learnt from remote PE routers are selectively installed into the FIB are selectively installed into the FIB while the remaining routes
while the remaining routes including local CE host routes are including local CE host routes are installed into the FIB by default
installed into the FIB by default as before. as before.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology 2. Terminology
This memo makes use of the terms defined in [RFC4364]. This memo makes use of the terms defined in [RFC4364].
3. Solution Description 3. Solution Description
+----------+ +----------+
+----+PE/RR(APR)+----+ +----+PE/RR(APR)+----+
+------------------+ | +----------+ | +---------------_--+ +------------------+ | +----------+ | +------------------+
|VPN_A:192.0.2.1/24| | | |VPN_A:192.0.2.1/24| |VPN_A:192.0.2.1/24| | | |VPN_A:192.0.2.1/24|
| \ | | | | / | | \ | | | | / |
| +------+ \ ++---+-+ +-+---++/ +------+ | | +------+ \ ++---+-+ +-+---++/ +------+ |
| |Host A+------_+ PE-1 | | PE-2 +------+Host B| | | |Host A+------_+ PE-1 | | PE-2 +------+Host B| |
| +------+\ ++-+-+-+ +-+-+-++ /+------+ | | +------+\ ++-+-+-+ +-+-+-++ /+------+ |
| 192.0.2.2/24 | | | | | | 192.0.2.3/24 | | 192.0.2.2/24 | | | | | | 192.0.2.3/24 |
| | | | | | | | | | | | | | | |
| DC West | | | IP/MPLS Backbone | | | DC East | | DC West | | | IP/MPLS Backbone | | | DC East |
+------------------+ | | | | +------------------+ +------------------+ | | | | +------------------+
| +--------------------+ | | +--------------------+ |
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+--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+
|192.0.2.3/32 | PE-2 | IBGP | No | |192.0.2.3/32 |192.0.2.3| Direct | Yes | |192.0.2.3/32 | PE-2 | IBGP | No | |192.0.2.3/32 |192.0.2.3| Direct | Yes |
+--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+
|192.0.2.0/25 | APR | IBGP | Yes | |192.0.2.0/25 | APR | IBGP | Yes | |192.0.2.0/25 | APR | IBGP | Yes | |192.0.2.0/25 | APR | IBGP | Yes |
+--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+
|192.0.2.128/25| APR | IBGP | Yes | |192.0.2.128/25| APR | IBGP | Yes | |192.0.2.128/25| APR | IBGP | Yes | |192.0.2.128/25| APR | IBGP | Yes |
+--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+
|192.0.2.0/24 |192.0.2.1| Direct | Yes | |192.0.2.0/24 |192.0.2.1| Direct | Yes | |192.0.2.0/24 |192.0.2.1| Direct | Yes | |192.0.2.0/24 |192.0.2.1| Direct | Yes |
+--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+ +--------------+---------+--------+------+
Figure 1: Selective FIB Installation Example Figure 1: Selective IPv4 FIB Installation Example
+----------+
+----+PE/RR(APR)+----+
+--------------------+ | +----------+ | +----------------+
|VPN_A: | | | |VPN_A: |
|2001:db8::1/64 | | | |2001:db8::1/64 |
| \ | | | | / |
| +------+ \ ++---+-+ +-+---++/ +------+ |
| |Host A+------_+ PE-1 | | PE-2 +------+Host B| |
| +------+\ ++-+-+-+ +-+-+-++ /+------+ |
| 2001:db8::2/64 | | | | | | 2001:db8::3/64 |
| | | | | | | |
| DC West | | | IP/MPLS Backbone | | | DC East |
+------------------+ | | | | +------------------+
| +--------------------+ |
| |
VRF: V VRF:V
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
| Prefix | Nexthop |Protocol|In_FIB| | Prefix | Nexthop |Protocol|In_FIB|
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
|2001:db8::1/64 | ::1 | Direct | Yes | |2001:db8::1/64 | ::1 | Direct | Yes |
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
|2001:db8::2/64 |2001:db8::2| Direct | Yes | |2001:db8::2/64 | PE-1 | IBGP | No |
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
|2001:db8::3/64 | PE-2 | IBGP | No | |2001:db8::3/64 |2001:db8::3| Direct | Yes |
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
|2001:db8::0/63 | APR | IBGP | Yes | |2001:db8::0/63 | APR | IBGP | Yes |
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
|2001:db8::128/63| APR | IBGP | Yes | |2001:db8::128/63| APR | IBGP | Yes |
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
|2001:db8::0/64 |2001:db8::1| Direct | Yes | |2001:db8::0/64 |2001:db8::1| Direct | Yes |
+----------------+-----------+--------+------+ +----------------+-----------+--------+------+
Figure 2: Selective IPv6 FIB Installation Example
To reduce the FIB size of PE routers, the selective FIB installation To reduce the FIB size of PE routers, the selective FIB installation
concept as described in [I-D.ietf-grow-va] can be leveraged in the concept as described in [I-D.ietf-grow-va] can be leveraged in the
Virtual Subnet context. Take the VPN instance demonstrated in Virtual Subnet context. Take the VPN instance demonstrated in
Figure 1 as an example, the FIB reduction procedures are described as Figure 1 or Figure 2 as an example, the FIB reduction procedures are
follows: described as follows:
1. Multiple more specific prefixes (e.g., 192.0.2.0/25 and 1. Multiple more specific prefixes (e.g., 192.0.2.0/25 and
192.0.2.128/25) corresponding to an extended subnet (i.e., 192.0.2.128/25 in IPv4 example, or 2001:db8::0/63 and
192.0.2.0/24) are specified as Virtual Prefixes (VPs). 2001:db8::128/63 in IPv6 example ) corresponding to an extended
subnet (i.e., 192.0.2.0/24 in IPv4 example, or 2001:db8::0/64 in
IPv6 example) are specified as Virtual Prefixes (VPs).
Meanwhile, one or more PE routers (or route reflectors) are Meanwhile, one or more PE routers (or route reflectors) are
configured as Aggregation Point Routers (APR) for each VP. The configured as Aggregation Point Routers (APR) for each VP. The
APRs for a given VP would install a null route to that VP while APRs for a given VP would install a null route to that VP while
propagating a route to that VP via the L3VPN signaling. propagating a route to that VP via the L3VPN signaling.
2. For a given host route in the routing table which is learnt from 2. For a given host route in the routing table which is learnt from
any remote PE router, PE routers which are non-APRs for any VP any remote PE router, PE routers which are non-APRs for any VP
covering this host route would not install it into the FIB by covering this host route would not install it into the FIB by
default. In contrast, PE routers (or route reflectors) which are default. In contrast, PE routers (or route reflectors) which are
APRs for any VP covering that host route would install it into APRs for any VP covering that host route would install it into
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corresponding host route is found but not yet installed into the FIB, corresponding host route is found but not yet installed into the FIB,
it would be installed into the FIB. To provide robust protection it would be installed into the FIB. To provide robust protection
against DoS attacks on the control plane, rate-limiting of the above against DoS attacks on the control plane, rate-limiting of the above
packets sent to the control plane MUST be enabled. Those FIB entries packets sent to the control plane MUST be enabled. Those FIB entries
for remote CE host routes which are on-demand installed on non-APR PE for remote CE host routes which are on-demand installed on non-APR PE
routers would expire if not used for a certain period of time. routers would expire if not used for a certain period of time.
4. Acknowledgements 4. Acknowledgements
The authors would like to thank Susan Hares, Yongbing Fan, Robert The authors would like to thank Susan Hares, Yongbing Fan, Robert
Raszuk and Bruno Decraene for their valuable suggestions on this Raszuk, Bruno Decraene and Fred Baker for their valuable suggestions
document. on this document.
5. IANA Considerations 5. IANA Considerations
The type value for the Extended Communities Attributes as described The type value for the Extended Communities Attributes as described
in this doc is required to be allocated by the IANA. in this doc is required to be allocated by the IANA.
6. Security Considerations 6. Security Considerations
Those security considerations as described in Those security considerations as described in [RFC7814] are
[I-D.ietf-bess-virtual-subnet] are applicable to this document. This applicable to this document. This document does not introduce any
document does not introduce any new security risk. new security risk.
7. References 7. References
7.1. Normative References 7.1. Normative References
[I-D.ietf-bess-virtual-subnet]
Xu, X., Jacquenet, C., Raszuk, R., Boyes, T., and B. Fee,
"Virtual Subnet: A BGP/MPLS IP VPN-based Subnet Extension
Solution", draft-ietf-bess-virtual-subnet-07 (work in
progress), December 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <http://www.rfc-editor.org/info/rfc4364>. 2006, <http://www.rfc-editor.org/info/rfc4364>.
[RFC7814] Xu, X., Jacquenet, C., Raszuk, R., Boyes, T., and B. Fee,
"Virtual Subnet: A BGP/MPLS IP VPN-Based Subnet Extension
Solution", RFC 7814, DOI 10.17487/RFC7814, March 2016,
<http://www.rfc-editor.org/info/rfc7814>.
7.2. Informative References 7.2. Informative References
[I-D.ietf-grow-va] [I-D.ietf-grow-va]
Francis, P., Xu, X., Ballani, H., Jen, D., Raszuk, R., and Francis, P., Xu, X., Ballani, H., Jen, D., Raszuk, R., and
L. Zhang, "FIB Suppression with Virtual Aggregation", L. Zhang, "FIB Suppression with Virtual Aggregation",
draft-ietf-grow-va-06 (work in progress), December 2011. draft-ietf-grow-va-06 (work in progress), December 2011.
Authors' Addresses Authors' Addresses
Xiaohu Xu Xiaohu Xu
Huawei Huawei
Email: xuxiaohu@huawei.com Email: xuxiaohu@huawei.com
Christian Jacquenet Christian Jacquenet
Orange Orange
Email: christian.jacquenet@orange.com Email: christian.jacquenet@orange.com
Truman Boyes Truman Boyes
Bloomberg LP Bloomberg LP
Email: tboyes@bloomberg.net Email: tboyes@bloomberg.net
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