Network Working Group Y. Lucy
Internet-Draft S. Zhuang
Intended status: Standards Track W. Hao
Expires: September 18, 2016 Huawei Technologies
March 17, 2016

BGP Flowspec Redirect to VPN RD Extended Community
draft-yong-idr-flowspec-redirect-vpn-rd-00

Abstract

This document defines a new type of the redirect extended community, called as Redirect to VPN RD Extended Community. When activated, the Redirect to VPN RD Extended Community is used to identify the unique VPN instance within a router.

Requirements Language

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].

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on September 18, 2016.

Copyright Notice

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Table of Contents

1. Introduction

"Dissemination of Flow Specification Rules" [RFC5575], commonly known as BGP Flowspec, provided for a BGP Extended Community [RFC4360][RFC4360] that served to redirect traffic that matched the flow specification's Network Layer Reachability Information (NLRI) to a Virtual Routing and Forwarding (VRF) instance that lists the specified route-target in its import policy. In that RFC, the Redirect Extended Community was documented as follows:

: +--------+--------------------+--------------------------+
: | type   | extended community | encoding                 |
: +--------+--------------------+--------------------------+
: | 0x8008 | redirect           | 6-byte Route Target      |
: +--------+--------------------+--------------------------+
: 
: [...]
: 
: Redirect:  The redirect extended community allows the traffic to be
: redirected to a VRF routing instance that lists the specified
: route-target in its import policy. If several local instances
: match this criteria, the choice between them is a local matter
: (for example, the instance with the lowest Route Distinguisher
: value can be elected). This extended community uses the same
: encoding as the Route Target extended community [RFC4360].
: [...]
: 
: 11. IANA Considerations
: [...]
: 
: The following traffic filtering flow specification rules have been
: allocated by IANA from the "BGP Extended Communities Type -
: Experimental Use" registry as follows:
: [...]
: 
: 0x8008 - Flow spec redirect
    

[RFC7674] updates RFC 5575 ("Dissemination of Flow Specification Rules") to clarify the formatting of the BGP Flowspec Redirect Extended Community. This document defines the following redirect extended communities:

+--------+--------------------+-------------------------------------+
| type   | extended community | encoding                            |
+--------+--------------------+-------------------------------------+
| 0x8008 | redirect AS-2byte  | 2-octet AS, 4-octet Value           | 
| 0x8108 | redirect IPv4      | 4-octet IPv4 Address, 2-octet Value |
| 0x8208 | redirect AS-4byte  | 4-octet AS, 2-octet Value           |
+--------+--------------------+-------------------------------------+
    

2. Operation Concerns in Redirect VRF Action

Following example is a case used in a backbone network.

Traffic Analyzer is installed at the edge of the backbone to detect the attack.

Scrubbing Center is installed at the edge of the backbone tackle the attack.

VRF scrubbing-vpn is configured on R1 and R2. A default route in R1's scrubbing-vpn VRF is configured to reach the Scrubbing Center, and MP-BGP is configured to advertise the default route from VRF scrubbing-vpn to the remote router R2.

       +--------+
       |Traffic |
   +---+Analyzer|
   |   +--------+                                VPN instances in R2:
   |
 | |                                             ip vpn-instance vpn1
 | |FlowSpec rule with                            RD: 10:1
 | |Redirect RT: 100:1                            IRT: 10:1 100:1
 v |                                              ERT: 10:1 100:1
   |    Scrubbing vrf in R1:
   |    ip vpn-instance scrubbing-vpn            ip vpn-instance scrubbing-vpn
   |     RD: 100:1                                RD: 100:1
   |     IRT: 100:1                               IRT: 100:1
+--+--+  ERT: 100:1                      +-----+  ERT: 100:1
|  R1 +----------------------------------+ R2  +
+-----+      ------------->              +-----+ ip vpn-instance vpn2
   |         FlowSpec rule with                   RD: 200:1
   |         Redirect RT: 100:1                   IRT: 10:1 100:1
   |                                              ERT: 10:1
   |                 <------Redirect DDoS Traffic
   |                        to Scrubbing Center from R2
   |   +----------+
   |   |Scrubbing |
   +---+Center    |
       +----------+

Figure 1 Redirect DDoS Traffic to Scrubbing Center Using Redirect VPN RT

R1 will advertise the receiving Flowspec rule to R2.

If the VRF scrubbing-vpn on R2 is the only VRF routing instance, then the receiving Flowspec rule from R1 can be imported by the VRF routing instance scrubbing-vpn. The attack traffic that matches the Flowspec rule on R2 will be redirected to the VRF scrubbing-vpn and sent to the Scrubbing Center.

However in this case, there are several local instances on R2 can match the Redirect RT: 100:1(as shown in following table). To make it work, according to RFC 5575, an operator has to configure R2 so that 'Redirect to VPN' will point to the scrubbing-vpn, which introduces operation complex and/or prone to an error. To avoid this configuration, a unique RT value for BGP FS 'Redirect to VPN' action has to be selected, which can be an operation complex in a large network.

+---------------+--------------------+----------------+
| VRF           | IRT                | RD             |
+---------------+--------------------+----------------+
| vpn1          | 10:1 100:1         | 10:1           |
| scrubbing-vpn | 100:1              | 100:1          |
| vpn2          | 10:1 100:1         | 200:1          |
+---------------+--------------------+----------------+

The reason for the above issue is that the IRT isn't unique on one router, for example, IRT 100:1 can be assigned to multiple VRF instances: vpn1, scrubbing-vpn and vpn2.

The Route Distinguisher is unique on one router, In order to address this operational concern, this document introduces a new type of the redirect extended community, called as Redirect to VPN RD Extended Community, When activated, the Redirect to VPN RD Extended Community is used to identify the unique VPN instance within a router.

3. Redirect to VPN RD Extended Community Format

This document defines a new type of the redirect extended community, called as Redirect to VPN RD Extended Community. This extended community is a new transitive extended community with the Sub-Type field is TBD. The IANA registry of BGP Extended Communities clearly identifies communities of specific formats: "Two-octet AS Specific Extended Community" [RFC4360], "Four-octet AS Specific Extended Community" [RFC5668], and "IPv4 Address Specific Extended Community" [RFC4360]. Route Targets [RFC4360] identify this format in the high-order (Type) octet of the Extended Community, Redirect to VPN RD Extended Community uses the same mechanism

This document defines the following VPN RD Extended Communities:

+------+--------+--------------------+-------------------------------------+
| Type |Sub-Type| Extended Community | Encoding                            |
+------+--------+--------------------+-------------------------------------+
| 0x80 | TBD    | AS-2byte RD        | 2-octet AS, 4-octet Value           |
| 0x81 | TBD    | IPv4 RD            | 4-octet IPv4 Address, 2-octet Value |
| 0x82 | TBD    | AS-4byte RD        | 4-octet AS, 2-octet Value           |
+------+--------+--------------------+-------------------------------------+
                Figure 2: VPN RD Extended Communities

It should be noted that the low-order nibble of the Redirect's Type field corresponds to the Route Target Extended Community format field (Type). (See Sections 3.1, 3.2, and 4 of [RFC4360] plus Section 2 of [RFC5668].) The low-order octet (Sub-Type) of the Redirect to VPN RD Extended Community is TBD, in contrast to 0x02 for Route Targets and 0x08 for Redirect to VPN RT Extended Community.

4. Using Redirect VPN RD Extended Community

Upon detecting the attack target to the user of the backbone network, Traffic Analyzer will push a Flowspec rule to R1 with Redirect VPN RD: 100:1.

R1 will advertise the receiving Flowspec rule to R2.

In R2, the receiving Flowspec rule from R1 can be imported by the VRF routing instance scrubbing-vpn. The attack traffic that matches the Flowspec rule on R2 will be correctly redirected to the VRF scrubbing-vpn and sent to the Scrubbing Center.

       +--------+
       |Traffic |
   +---+Analyzer|
   |   +--------+                                VPN instances in R2:
   |
 | |                                             ip vpn-instance vpn1
 | |FlowSpec rule with                            RD: 10:1
 | |Redirect VPN RD: 100:1                        IRT: 10:1 100:1
 v |                                              ERT: 10:1 100:1
   |    Scrubbing vrf in R1:
   |    ip vpn-instance scrubbing-vpn            ip vpn-instance scrubbing-vpn
   |     RD: 100:1                                RD: 100:1
   |     IRT: 100:1                               IRT: 100:1
+--+--+  ERT: 100:1                      +-----+  ERT: 100:1
|  R1 +----------------------------------+ R2  +
+-----+      ------------->              +-----+ ip vpn-instance vpn2
   |         FlowSpec rule with                   RD: 200:1
   |         Redirect VPN RD: 100:1               IRT: 10:1 100:1
   |                                              ERT: 10:1
   |                 <------Redirect DDoS Traffic
   |                        to Scrubbing Center from R2
   |   +----------+
   |   |Scrubbing |
   +---+Center    |
       +----------+

Figure 3: Redirect DDoS Traffic to Scrubbing Center Using Redirect VPN RD

The above procedures assume that all PEs are upgraded to support the Redirect to VPN RD Extended Community.

5. IANA Considerations

TBD.

6. Security Considerations

TBD.

7. References

7.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC4271] Rekhter, Y., Li, T. and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006.
[RFC4360] Sangli, S., Tappan, D. and Y. Rekhter, "BGP Extended Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, February 2006.
[RFC4760] Bates, T., Chandra, R., Katz, D. and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, DOI 10.17487/RFC4760, January 2007.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February 2009.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J. and D. McPherson, "Dissemination of Flow Specification Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009.
[RFC5668] Rekhter, Y., Sangli, S. and D. Tappan, "4-Octet AS Specific BGP Extended Community", RFC 5668, DOI 10.17487/RFC5668, October 2009.

7.2. Informative References

[RFC7674] Haas, J., "Clarification of the Flowspec Redirect Extended Community", RFC 7674, DOI 10.17487/RFC7674, October 2015.

Authors' Addresses

lucy.yong Huawei Technologies EMail: lucy.yong@huawei.com
Shunwan Zhuang Huawei Technologies Huawei Bld., No.156 Beiqing Rd. Beijing, 100095 China EMail: zhuangshunwan@huawei.com
Weiguo Hao Huawei Technologies 101 Software Avenue, Nanjing, 210012 China EMail: haoweiguo@huawei.com