One document matched: draft-ietf-idr-bgp-flowspec-label-00.xml
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<rfc category="std" docName="draft-ietf-idr-bgp-flowspec-label-00"
ipr="trust200902">
<front>
<title abbrev="BGP FlowSpec">Carrying Label Information for BGP
FlowSpec</title>
<author fullname="Qiandeng Liang" initials="Q." surname="Liang">
<organization>Huawei</organization>
<address>
<postal>
<street>101 Software Avenue, Yuhuatai District</street>
<city>Nanjing,</city>
<code>210012</code>
<country>China</country>
</postal>
<email>liangqiandeng@huawei.com</email>
</address>
</author>
<author fullname="Susan Hares " initials="S." surname="Hares ">
<organization>Huawei</organization>
<address>
<postal>
<street>7453 Hickory Hill</street>
<city>Saline, MI</city>
<code>48176</code>
<country>USA</country>
</postal>
<email>shares@ndzh.com</email>
</address>
</author>
<author fullname="Jianjie You" initials="J." surname="You">
<organization>Huawei</organization>
<address>
<postal>
<street>101 Software Avenue, Yuhuatai District</street>
<city>Nanjing,</city>
<code>210012</code>
<country>China</country>
</postal>
<email>youjianjie@huawei.com</email>
</address>
</author>
<author fullname="Robert Raszuk" initials="R." surname="Raszuk">
<organization>Nozomi</organization>
<address>
<email>robert@raszuk.net</email>
</address>
</author>
<author fullname="Dan Ma " initials="D." surname="Ma">
<organization>Cisco Systems</organization>
<address>
<email>danma@cisco.com</email>
</address>
</author>
<date year="2016" />
<area>Rtg Area</area>
<workgroup>Idr Working Group</workgroup>
<keyword>RFC</keyword>
<keyword>Request for Comments</keyword>
<keyword>I-D</keyword>
<keyword>Internet-Draft</keyword>
<keyword>BGP, FlowSpec</keyword>
<abstract>
<t>This document specifies a method in which the label mapping
information for a particular FlowSpec rule is piggybacked in the same
Border Gateway Protocol (BGP) Update message that is used to distribute
the FlowSpec rule. Based on the proposed method, the Label Switching
Routers (LSRs) (except the ingress LSR) on the Label Switched Path (LSP)
can use label to indentify the traffic matching a particular FlowSpec
rule; this facilitates monitoring and traffic statistics for FlowSpec
rules.</t>
</abstract>
<note title="Requirements Language ">
<t>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 <xref
target="RFC2119"></xref>.</t>
</note>
</front>
<middle>
<section anchor="intro" title="Introduction">
<t>This section provides the background for proposing a new action for
BGP Flow specification that push/pops MPLS or swaps MPLS tags. For those
familiar with BGP Flow specification (<xref target="RFC5575"></xref>,
<xref target="RFC7674"></xref>, <xref
target="I-D.ietf-idr-flow-spec-v6"></xref>, <xref
target="I-D.ietf-idr-flowspec-l2vpn"></xref>, <xref
target="I-D.ietf-idr-bgp-flowspec-oid"></xref> and MPLS (<xref
target="RFC3107"></xref>) can skip this background section.</t>
<section title="Background">
<t><xref target="RFC5575"></xref> defines the flow specification
(FlowSpec) that is an n-tuple consisting of several matching criteria
that can be applied to IP traffic. The matching criteria can include
elements such as source and destination address prefixes, IP protocol,
and transport protocol port numbers. A given IP packet is said to
match the defined flow if it matches all the specified criteria. <xref
target="RFC5575"></xref> also defines a set of filtering actions, such
as rate limit, redirect, marking, associated with each flow
specification. A new Border Gateway Protocol Network Layer
Reachability Information (BGP NLRI) (AFI/SAFI: 1/133 for IPv4,
AFI/SAFI: 1/134 for VPNv4) encoding format is used to distribute
traffic flow specifications.</t>
<t><xref target="RFC3107"></xref> specifies the way in which the label
mapping information for a particular route is piggybacked in the same
Border Gateway Protocol Update message that is used to distribute the
route itself. Label mapping information is carried as part of the
Network Layer Reachability Information (NLRI) in the Multiprotocol
Extensions attributes. The Network Layer Reachability Information is
encoded as one or more triples of the form <length, label,
prefix>. The NLRI contains a label is indicated by using Subsequent
Address Family Identifier (SAFI) value 4.</t>
<t><xref target="RFC4364"></xref> describes a method in which each
route within a Virtual Private Network (VPN) is assigned a
Multiprotocol Label Switching (MPLS) label. If the Address Family
Identifier (AFI) field is set to 1, and the SAFI field is set to 128,
the NLRI is an MPLS-labeled VPN-IPv4 address.</t>
</section>
<section title="MPLS Flow Specification Deployment">
<t>In BGP VPN/MPLS networks when flow specification policy rules exist
on multiple forwarding devices in the network bound with labels from
one or more LSPs, only the ingress LSR (Label Switching Router) needs
to identify a particular traffic flow based on the matching criteria
for flow. Once the flow is match by the ingress LSR, the ingress LSR
steers the packet to a corresponding LSP (Label Switched Path). Other
LSRs of the LSP just need to forward the packet according to the label
carried in it.</t>
</section>
</section>
<section title="Terminology">
<t>This section contains definitions of terms used in this document.</t>
<t><list>
<t>Flow Specification (FlowSpec): A flow specification is an n-tuple
consisting of several matching criteria that can be applied to IP
traffic, including filters and actions. Each FlowSpec consists of a
set of filters and a set of actions.</t>
</list></t>
</section>
<section title="Overview of Proposal">
<t>This document proposes adding a BGP-FS action in an extended
community alters the label switch path associated with a matched flow.
If the match does not have a label switch path, this action is
skipped.</t>
<t>The BGP flow specification (BGP-FS) policy rule could match on the
destination prefix and then utilize a BGP-FS action to adjust the label
path associated with it (push/pop/swap tags.) Or a BGP-FS policy rule
could match on any set of BGP-FS match conditions associated with a
BGP-FS action that adjust the label switch path (push/pop/swap).</t>
<t><xref target="I-D.ietf-idr-flowspec-mpls-match"></xref> provides a
match BGP-FS that may be used with this action to match and direct MPLS
packets.</t>
<t>Example of Use:</t>
<t>Forwarding information for the traffic from IP1 to IP2 in the
Routers:</t>
<figure>
<artwork> PE1: in(<IP2,IP1>) --> out(Label2)
ASBR1: in(Label2) --> out(Label3)
ASBR2: in(Label3) --> out(Label4)
PE2: in(Label4) --> out(--)</artwork>
</figure>
<t>Labels allocated by flow policy process:</t>
<figure>
<artwork> Label4 allocated by PE2
Label3 allocated by ASBR2
Label2 allocated by ASBR1</artwork>
</figure>
<figure align="left">
<artwork align="left">
|<------AS1----->| |<------AS2----->|
+-----+ +-----+ +-----+ +-----+
VPN 1,IP1..| PE1 |====|ASBR1|----|ASBR2|====| PE2 |..VPN1,IP2
+-----+ +-----+ +-----+ +-----+
| LDP LSP1 | | LDP LSP2 |
| -------> | | -------> |
|-------BGP VPN Flowspec LSP---->|
(Label1) (Label2) (Label3) (Label4)
Figure 1: Usage of FlowSpec with Label
</artwork>
</figure>
<t>BGP-FS rule1 (locally configured):</t>
<figure>
<artwork> Filters:
destination ip prefix:IP2/32
source ip prefix:IP1/32
Actions: Extended Communities
traffic-marking: 1
MPLS POP </artwork>
</figure>
<t>Note:</t>
<t>The following Extended Communities are added/deleted</t>
<figure>
<artwork> [rule-1a] BGP-FS action MPLS POP [used on PE2]
[rule-1b] BGP-FS action SWAP 4 [used on ASBR-2]
[rule-1c] BGP-FS action SWAP 3 [used on ASBR-1]
[rule-1d] BGP-FS action push 2 [used on PE1] </artwork>
</figure>
<figure>
<artwork>PE-2 Changes BGP-FS rule-1a to rule-1b prior to sending
Clears Extended Community: BGP-FS action MPLS POP
Adds Extended Community: BGP-FS action MPLS SWAP 4</artwork>
</figure>
<figure>
<artwork>ASBR-2 receives BGP-FS rule-1b (NRLI + 2 Extended Community)
Installs the BGP-FS rule-1b (MPLS SWAP 4, traffic-marking)
Changes BGP-FS rule-1b to rule-1c prior to sending to ASBR1
Clear Extended Community: BGP-FS action MPLS SWAP 4
Adds Extended Community: BGP-FS action MPLS SWAP 3</artwork>
</figure>
<figure>
<artwork>ASBR-1 Receives BGP-FS rule-1c (NLRI + 2 Extended Community)
Installs the BGP-FS rule-1c (MPLS SWAP 3, traffic-marking
Changes BGP-FS rule-1c to rule-1d prior to sending to PE-2
Clear Extended Community: BGP-FS action MPLS SWAP 3
Adds Extended Community: BGP-FS action MPLS SWAP 2 </artwork>
</figure>
<figure>
<artwork>PE-1 Receives BGP-FS rule-1d (NLRI + 2 Extended Communities)
Installs BGP-FS rule-1d action [MPLS SWAP 2, traffic-marking] </artwork>
</figure>
</section>
<section title="Protocol Extensions">
<t>In this document, BGP is used to distribute the FlowSpec rule bound
with label(s). A new label-action is defined as BGP extended community
value based on Section 7 of <xref target="RFC5575"></xref>.</t>
<figure>
<artwork align="center">
+--------+--------------------+--------------------------+
| type | extended community | encoding |
+--------+--------------------+--------------------------+
| TBD1 | label-action | MPLS tag |
+--------+--------------------+--------------------------+
</artwork>
</figure>
<t>Label-action is described below:<figure align="center">
<artwork> 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (TBD1 | OpCode|Reserve| order |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label
| Label | Exp |S| TTL | Stack
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry
</artwork>
</figure></t>
<t>The use and the meaning of these fields are as follows:<list>
<t>Type: the same as defined in <xref target="RFC4360"></xref></t>
<t>OpCode: Operation code<figure align="center">
<artwork>+------+------------------------------------------------------------+
|OpCode| Function |
+------+------------------------------------------------------------+
| 0 | Push the MPLS tag |
+------+------------------------------------------------------------+
| 1 | Pop the outermost MPLS tag in the packet |
+------+------------------------------------------------------------+
| 2 | Swap the MPLS tag with the outermost MPLS tag in the packet|
+------+------------------------------------------------------------+
| 3~15 | Reserved |
+------+------------------------------------------------------------+</artwork>
</figure><list>
<t>When the Opcode field is set to 0, the label stack entry
Should be pushed on the MPLS label stack.</t>
<t>When the OpCode field is set to 1, the label stack entry is
invalid, and the router SHOULD pop the existing outermost MPLS
tag in the packet.</t>
<t>When the OpCode field is set to 2, the router SHOULD swap the
label stack entry with the existing outermost MPLS tag in the
packet. If the packet has no MPLS tag, it just pushes the label
stack entry.</t>
<t>The OpCode 0 or 1 may be used in some SDN networks, such as
the scenario described in <xref
target="I-D.filsfils-spring-segment-routing-central-epe"></xref>.</t>
<t>The OpCode 2 can be used in traditional BGP MPLS/VPN
networks.</t>
</list></t>
<t>Reserved: all zeros.</t>
<t>Order: A FlowSpec rule MAY include one or more ordering
label-action(s). If multiple label action extended communities are
associated with a BGP-FS Rule, this gives the order of this in the
list. The Last action received for an order will be used.</t>
<t>Label: the same as defined in <xref target="RFC3032"></xref>.</t>
<t>Bottom of Stack (S): the same as defined in <xref
target="RFC3032"></xref>. It SHOULD be invalid, and set to zero by
default. It MAY be modified by the forwarding router locally.</t>
<t>Time to Live (TTL): the same as defined in<xref
target="RFC3032"></xref>. It MAY be modified by the forwarding
router locally.</t>
<t>Experimental Use (Exp): the same as defined in <xref
target="RFC3032"></xref>. It MAY be modified by the forwarding
router according to the local routing policy.</t>
</list></t>
</section>
<section title="IANA Considerations">
<t>For the purpose of this work, IANA should allocate the following
Extended community:<list>
<t>TBD1 for label-action</t>
</list></t>
</section>
<section title="Security considerations">
<t>This extension to BGP does not change the underlying security issues
inherent in the existing BGP.</t>
</section>
<section title="Acknowledgement">
<t>The authors would like to thank Shunwan Zhuang, Zhenbin Li, Peng Zhou
and Jeff Haas for their comments.</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC2119;
&RFC5575;
&RFC3107;
&RFC4364;
&RFC3032;
&RFC4360;
&RFC7674;
</references>
<references title="Informative References">
&I-D.filsfils-spring-segment-routing-central-epe;
&I-D.ietf-idr-flow-spec-v6;
&I-D.ietf-idr-flowspec-l2vpn;
&I-D.ietf-idr-bgp-flowspec-oid;
&I-D.ietf-idr-flowspec-mpls-match;
</references>
</back>
</rfc>
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