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Protecting the Router Control Plane
RFC 6192

Internet Engineering Task Force (IETF)                          D. Dugal
Request for Comments: 6192                              Juniper Networks
Category: Informational                                     C. Pignataro
ISSN: 2070-1721                                                  R. Dunn
                                                           Cisco Systems
                                                              March 2011

                  Protecting the Router Control Plane

Abstract

   This memo provides a method for protecting a router's control plane
   from undesired or malicious traffic.  In this approach, all
   legitimate router control plane traffic is identified.  Once
   legitimate traffic has been identified, a filter is deployed in the
   router's forwarding plane.  That filter prevents traffic not
   specifically identified as legitimate from reaching the router's
   control plane, or rate-limits such traffic to an acceptable level.

   Note that the filters described in this memo are applied only to
   traffic that is destined for the router, and not to all traffic that
   is passing through the router.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6192.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
   2. Applicability Statement .........................................4
   3. Method ..........................................................4
      3.1. Legitimate Traffic .........................................5
      3.2. Filter Design ..............................................6
      3.3. Design Trade-Offs ..........................................7
      3.4. Additional Protection Considerations ......................10
   4. Security Considerations ........................................10
   5. Acknowledgements ...............................................11
   6. Informative References .........................................12
   Appendix A. Configuration Examples ................................13
      A.1. Cisco Configuration .......................................13
      A.2. Juniper Configuration .....................................17

1.  Introduction

   Modern router architecture design maintains a strict separation of
   forwarding and router control plane hardware and software.  The
   router control plane supports routing and management functions.  It
   is generally described as the router architecture hardware and
   software components for handling packets destined to the device
   itself as well as building and sending packets originated locally on
   the device.  The forwarding plane is typically described as the
   router architecture hardware and software components responsible for
   receiving a packet on an incoming interface, performing a lookup to
   identify the packet's IP next hop and determine the best outgoing
   interface towards the destination, and forwarding the packet out
   through the appropriate outgoing interface.

   Visually, this architecture can be represented as the router's
   control plane hardware sitting on top of, and interfacing with, the
   forwarding plane hardware with interfaces connecting to other network
   devices.  See Figure 1.

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                             +----------------+
                             | Router Control |
                             |     Plane      |
                             +------+ +-------+
                                    | |
                               Router Control
                              Plane Protection
                                    | |
                             +------+ +-------+
                             |   Forwarding   |
               Interface X ==[     Plane      ]== Interface Y
                             +----------------+

                 Figure 1: Router Control Plane Protection

   Typically, forwarding plane functionality is realized in high-
   performance Application Specific Integrated Circuits (ASICs) that are
   capable of handling very high packet rates.  By contrast, the router
   control plane is generally realized in software on general-purpose
   processors.  While software instructions run on both planes, the
   router control plane hardware is usually not optimized for high-speed
   packet handling.  Given their differences in packet-handling
   capabilities, the router's control plane hardware is more susceptible
   to being overwhelmed by a Denial-of-Service (DoS) attack than the
   forwarding plane's ASICs.  It is imperative that the router control
   plane remain stable regardless of traffic load to and from the device
   because the router control plane is what drives the programming of
   the forwarding plane.

   The router control plane also processes traffic destined to the
   router, and because of the wider range of functionality is more
   susceptible to security vulnerabilities and a more likely target for
   a DoS attack than the forwarding plane.

   It is advisable to protect the router control plane by implementing
   mechanisms to filter completely or rate-limit traffic not required at
   the control plane level (i.e., unwanted traffic).  "Router control
   plane protection" is the concept of filtering or rate-limiting
   unwanted traffic that would be diverted from the forwarding plane up
   to the router control plane.  The closer the filters and rate
   limiters are to the forwarding plane and line-rate hardware, the more
   effective the protection is and the more resistant the system is to
   DoS attacks.  This memo demonstrates one example of how to deploy a
   policy filter that satisfies a set of sample traffic-matching,
   filtering, and rate-limiting criteria.

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   Note that the filters described in this memo are applied only to
   traffic that is destined for the router, and not to all traffic that
   is passing through the router.

2.  Applicability Statement

   The method described in Section 3 and depicted in Figure 1
   illustrates how to protect the router control plane from unwanted
   traffic.  Recognizing that deployment scenarios will vary, the exact
   implementation is not generally applicable in all situations.  The
   categorization of legitimate router control plane traffic is
   critically important in a successful implementation.

   The examples given in this memo are simplified and minimalistic,
   designed to illustrate the concept of protecting the router's control
   plane.  From them, operators can extrapolate specifics based on their
   unique configuration and environment.  This document is about
   semantics, and Appendix A exemplifies syntax.  For additional router
   vendor implementations, or other converged devices, the syntax should
   be translated to the respective language in a manner that preserves
   the semantics.

   Additionally, the need to provide the router control plane with
   isolation, stability, and protection against rogue packets has been
   incorporated into router designs for some time.  Consequently, there
   may be other vendor or implementation specific router control plane
   protection mechanisms that are active by default or always active.
   Those approaches may apply in conjunction with, or in addition to,
   the method described in Section 3 and illustrated in Appendices A.1
   and A.2.  Those implementations should be considered as part of an
   overall traffic management plan but are outside the scope of this
   document.

   This method is applicable for IPv4 as well as IPv6 address families,
   and the legitimate traffic example in Section 3.1 provides examples
   for both.

3.  Method

   In this memo, the authors demonstrate how a filter protecting the
   router control plane can be deployed.  In Section 3.1, a sample
   router is introduced, and all traffic that its control plane must
   process is identified.  In Section 3.2, filter design concepts are
   discussed.  Cisco (Cisco IOS software) and Juniper (JUNOS)
   implementations are provided in Appendices A.1 and A.2, respectively.

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3.1.  Legitimate Traffic

   In this example, the router control plane must process traffic (i.e.,
   traffic destined to the router and not through the router) per the
   following criteria:

   o  Drop all IP packets that are fragments (see Section 3.3)

   o  Permit ICMP and ICMPv6 traffic from any source, rate-limited to
      500 kbps for each category

   o  Permit OSPF traffic from routers within subnet 192.0.2.0/24 and
      OSPFv3 traffic from IPv6 Link-Local unicast addresses (fe80::/10)

   o  Permit internal BGP (iBGP) traffic from routers within subnets
      192.0.2.0/24 and 2001:db8:1::/48

   o  Permit external BGP (eBGP) traffic from eBGP peers 198.51.100.25,
      198.51.100.27, 198.51.100.29, and 198.51.100.31; and IPv6 peers
      2001:db8:100::25, 2001:db8:100::27, 2001:db8:100::29, and
      2001:db8:100::31

   o  Permit DNS traffic from DNS servers within subnet 198.51.100.0/30
      and 2001:db8:100:1::/64

   o  Permit NTP traffic from NTP servers within subnet 198.51.100.4/30
      and 2001:db8:100:2::/64

   o  Permit Secure SHell (SSH) traffic from network management stations
      within subnet 198.51.100.128/25 and 2001:db8:100:3::/64

   o  Permit Simple Network Management Protocol (SNMP) traffic from
      network management stations within subnet 198.51.100.128/25 and
      2001:db8:100:3::/64

   o  Permit RADIUS authentication and accounting replies from RADIUS
      servers 198.51.100.9, 198.51.100.10, 2001:db8:100::9, and
      2001:db8:100::10 that are listening on UDP ports 1812 and 1813
      (Internet Assigned Numbers Authority (IANA) RADIUS ports).  Note
      that this does not accommodate a server using the original UDP
      ports of 1645 and 1646

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   o  Permit all other IPv4 and IPv6 traffic that was not explicitly
      matched in a class above, rate-limited to 500 kbps, and drop above
      that rate for each category

   o  Permit non-IP traffic (e.g., Connectionless Network Service
      (CLNS), Internetwork Packet Exchange (IPX), PPP Link Control
      Protocol (LCP), etc.), rate-limited to 250 kbps, and drop all
      remaining traffic above that rate

   The characteristics of legitimate traffic will vary from network to
   network.  To illustrate this, a router implementing the DHCP relay
   function can rate-limit inbound DHCP traffic from clients and
   restrict traffic from servers to a list of known DHCP servers.  The
   list of criteria above is provided for example only.

3.2.  Filter Design

   A filter is installed on the forwarding plane.  This filter counts
   and applies the actions to the categories of traffic described in
   Section 3.1.  Because the filter is enforced in the forwarding plane,
   it prevents traffic from consuming bandwidth on the interface that
   connects the forwarding plane to the router control plane.  The
   counters serve as an important forensic tool for the analysis of
   potential attacks, and as an invaluable debugging and troubleshooting
   aid.  By adjusting the granularity and order of the filters, more
   granular forensics can be performed (i.e., create a filter that
   matches only traffic allowed from a group of IP addresses for a given
   protocol followed by a filter that denies all traffic for that
   protocol).  This would allow for counters to be monitored for the
   allowed protocol filter, as well as any traffic matching the specific
   protocol that didn't originate from the explicitly allowed hosts.

   In addition to the filters, rate limiters for certain classes of
   traffic are also installed in the forwarding plane as defined in
   Section 3.1.  These rate limiters help further control the traffic
   that will reach the router control plane for each filtered class as
   well as all traffic not matching an explicit class.  The actual rates
   selected for various classes are network deployment specific;
   analysis of the rates required for stability should be done
   periodically.  It is important to note that the most significant
   factor to consider regarding the traffic profile going to the router
   control plane is the packets per second (pps) rate.  Therefore,
   careful consideration must be given to determine the maximum pps rate
   that could be generated from a given set of packet size and bandwidth
   usage scenarios.

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   Syntactically, these filters explicitly define "allowed" traffic
   (including IP addresses, protocols, and ports), define acceptable
   actions for these acceptable traffic profiles (e.g., rate-limit or
   simply permit the traffic), and then discard all traffic destined to
   the router control plane that is not within the specifications of the
   policy definition.

   In an actual production environment, predicting a complete and
   exhaustive list of traffic necessary to reach the router's control
   plane for day-to-day operation may not be as obvious as the example
   described herein.  One recommended method to gauge this set of
   traffic is to allow all traffic initially, and audit the traffic that
   reaches the router control plane before applying any explicit filters
   or rate limits.  See Section 3.3 below for more discussion of this
   topic.

   The filter design provided in this document is intentionally limited
   to attachment at the local router in question (e.g., a "service-
   policy" attached to the "control-plane" in Cisco IOS, or a firewall
   filter attached to the "lo0" interface in JUNOS).  While virtually
   all production environments utilize and rely heavily upon edge
   protection or interface filtering, these methods of router protection
   are beyond the intended scope of this document.  Additionally, the
   protocols themselves that are allowed to reach the router control
   plane (e.g., OSPF, RSVP, TCP, SNMP, DNS, NTP, and inherently, SSH,
   TLS, ESP, etc.) may have cryptographic security methods applied to
   them, and the method of router control plane protection provided
   herein is not a replacement for those cryptographic methods.

3.3.  Design Trade-Offs

   In designing the protection method, there are two independent parts
   to consider: the classification of traffic (i.e., which traffic is
   matched by the filters), and the policy actions taken on the
   classified traffic (i.e., drop, permit, rate-limit, etc.).

   There are different levels of granularity utilized for traffic
   classification.  For example, allowing all traffic from specific
   source IP addresses versus allowing only a specific set of protocols
   from those specific source IP addresses will each affect a different
   subset of traffic.

   Similarly, the policy actions taken on the classified traffic have
   degrees of impact that may not become immediately obvious.  For
   example, discarding all ICMP traffic will have a negative impact on
   the operational use of ICMP tools such as ping or traceroute to debug
   network issues or to test deployment of a new circuit.  Expanding on
   this, in a real production network, an astute operator could define

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   varying rate limits for ICMP such that internal traffic is granted
   uninhibited access to the router control plane, while traffic from
   external addresses is rate-limited.  Operators should pay special
   attention to the new functionality and roles that ICMPv6 has in the
   overall operation of IPv6 when designing the rate-limit policies.
   Example functions include Neighbor Discovery (ND) and Multicast
   Listener Discovery version 2 (MLDv2).

   It is important to note that both classification and policy action
   decisions are accompanied by respective trade-offs.  Two examples of
   these trade-off decisions are operational complexity at the expense
   of policy and statistics-gathering detail, and tighter protection at
   the expense of network supportability and troubleshooting ability.

   Two types of traffic that need special consideration are IP fragments
   and IP optioned packets:

   o  For network deployments where IP fragmentation is necessary, a
      blanket policy of dropping all fragments destined to the router
      control plane may not be feasible.  However, many deployments
      allow network configurations such that the router control plane
      should never see a fragmented datagram.  Since many attacks rely
      on IP fragmentation, the example policy included herein drops all
      fragments destined to the router control plane.

   o  Similarly, some deployments may choose to drop all IP optioned
      packets.  Others may need to loosen the constraint to allow for
      protocols that require IP optioned packets such as the Resource
      Reservation Protocol (RSVP).  The design trade-off is that
      dropping all IP optioned packets protects the router from attacks
      that leverage malformed options, as well as attacks that rely on
      the slow-path processing (i.e., software processing path) of IP
      optioned packets.  For network deployments where the protocols do
      not use IP options, the filter is simpler to design in that it can
      drop all packets with any IP option set.  However, for networks
      utilizing protocols relying on IP options, the filter to identify
      the legitimate packets is more complex.  If the filter is not
      designed correctly, it could result in the inadvertent blackholing
      of traffic for those protocols.  This document does not include
      filter configurations for IP optioned packets; additional
      explanations regarding the filtering of packets based on the IP
      options they contain can be found in [IP-OPTIONS-FILTER].

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   The goal of the method for protecting the router control plane is to
   minimize the possibility for disruptions by reducing the vulnerable
   surface, which is inversely proportional to the granularity of the
   filter design.  The finer the granularity of the filter design (e.g.,
   filtering a more targeted subset of traffic from the rest of the
   policed traffic, or isolating valid source addresses into a different
   class or classes), the smaller the probability of disruption.

   In addition to the traffic that matches explicit classes, care should
   be taken on the policy decision that governs the handling of traffic
   that would fall through the classification.  Typically, that traffic
   is referred to as traffic that gets matched in a default class.  It
   may also be traffic that matches a blanket protocol specific class
   where previous classes that have more granular classification did not
   match all packets for that specific protocol.  The ideal policy would
   have explicit classes to match only the traffic specifically required
   at the router control plane and would drop all other traffic that
   does not match a predefined class.  As most vendor implementations
   permit all traffic hitting the default class, an explicit drop action
   would need to be configured in the policy such that the traffic
   hitting that default class would be dropped, versus being permitted
   and delivered to the router control plane.  This approach requires
   rigorous traffic pattern identification such that a default drop
   policy does not break existing device functionality.  The approach
   defined in this document allows the default traffic and rate-limits
   it as opposed to dropping it.  This approach was chosen as a way to
   give the operator time to evaluate and characterize traffic in a
   production scenario prior to dropping all traffic not explicitly
   matched and permitted.  However, it is highly recommended that after
   monitoring the traffic matching the default class, explicit classes
   be defined to catch the legitimate traffic.  After all legitimate
   traffic has been identified and explicitly allowed, the default class
   should be configured to drop any remaining traffic.

   Additionally, the baselining and monitoring of traffic flows to the
   router's control plane are critical in determining both the rates and
   granularity of the policies being applied.  It is also important to
   validate the existing policies and rules or update them as the
   network evolves and its traffic dynamics change.  Some possible ways
   to achieve this include individual policy counters that can be
   exported or retrieved, for example via SNMP, and logging of filtering
   actions.

   Finally, the use of flow-based behavioral analysis or command-line
   interface (CLI) functions to identify what client/server functions a
   given router's control plane handles would be very useful during
   initial policy development phases, and certainly for ongoing forensic
   analysis.

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3.4.  Additional Protection Considerations

   In addition to the design described in this document of defining
   "allowed" traffic (i.e., identifying traffic that the control plane
   must process) and limiting (e.g., rate-limiting or blocking) the
   rest, the router control plane protection method can be applied to
   thwart specific attacks.  In particular, it can be used to protect
   against TCP SYN flooding attacks and other Denial-of-Service attacks
   that starve router control plane resources.

4.  Security Considerations

   The filters described in this document leave the router susceptible
   to discovery from any host in the Internet.  If network operators
   find this risk objectionable, they can reduce the exposure to
   discovery with ICMP by restricting the sub-networks from which ICMP
   Echo requests and potential traceroute packets (i.e., packets that
   would trigger an ICMP Time Exceeded reply) are accepted, and
   therefore to which sub-networks ICMP responses (ICMP Echo Reply and
   Time Exceeded) are sent.  A similar concern exists for ICMPv6 traffic
   but on a broader level due to the additional functionalities
   implemented in ICMPv6.  Filtering recommendations for ICMPv6 can be
   found in [RFC4890].  Moreover, different rate-limiting policies may
   be defined for internally (e.g., from the Network Operations Center
   (NOC)) versus externally sourced traffic.  Note that this document is
   not targeted at the specifics of ICMP filtering or traffic filtering
   designed to prevent device discovery.

   The filters described in this document do not block unwanted traffic
   having spoofed source addresses that match a defined traffic profile
   as discussed in Section 3.1.  Network operators can mitigate this
   risk by preventing source address spoofing with filters applied at
   the network edge.  Refer to Section 5.3.8 of [RFC1812] for more
   information regarding source address validation.  Other methods also
   exist for limiting exposure to packet spoofing, such as the
   Generalized Time to Live (TTL) Security Mechanism (GTSM) [RFC5082]
   and Ingress Filtering [RFC2827] [RFC3704].

   The ICMP rate limiter specified for the filters described in this
   document protects the router from floods of ICMP traffic; see
   Sections 3.1 and 3.3 for details.  However, during an ICMP flood,
   some legitimate ICMP traffic may be dropped.  Because of this, when
   operators discover a flood of ICMP traffic, they are highly motivated
   to stop it at the source where the traffic is being originated.

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   Additional considerations pertaining to the usage and handling of
   traffic that utilizes the IP Router Alert Options can be found in
   [RTR-ALERT-CONS], and additional IP options filtering explanations
   can be found in [IP-OPTIONS-FILTER].

   The treatment of exception traffic in the forwarding plane and the
   generation of specific messages by the router control plane also
   require protection from a DoS attack.  Specifically, the generation
   of ICMP Unreachable messages by the router control plane needs to be
   rate-limited, either implicitly within the router's architecture or
   explicitly through configuration.  When possible, different ICMP
   Destination Unreachable codes (e.g., "fragmentation needed and DF
   set") or "Packet Too Big" messages can receive a different rate-
   limiting treatment.  Continuous benchmarking of router-generated ICMP
   traffic should be done before applying rate limits such that
   sufficient headroom is included to prevent inadvertent Path Maximum
   Transmission Unit Discovery (PMTUD) blackhole scenarios during normal
   operation.  It is also recommended to deploy explicit rate limiters
   where possible to improve troubleshooting and monitoring capability.
   The explicit rate limiters in a class allow for monitoring tools to
   detect and report when these rate limiters become active (i.e., when
   traffic is policed).  This in turn serves as an indicator that either
   the normal traffic rates have increased or "out of policy" traffic
   rates have been detected.  More thorough analysis of the traffic
   flows and rate-limited traffic is needed to identify which of these
   two cases triggered the rate limiters.  For additional information
   regarding specific ICMP rate-limiting, see Section 4.3.2.8 of
   [RFC1812].

   Additionally, the handling of TTL / Hop Limit expired traffic needs
   protection.  This traffic is not necessarily addressed to the device,
   but it can get sent to the router control plane to process the TTL /
   Hop Limit expiration.  For example, rate-limiting the TTL / Hop Limit
   expired traffic before sending the packets to the router control
   plane component that will generate the ICMP error, and distributing
   the sending of ICMP errors to Line Card CPUs, are protection
   mechanisms that mitigate attacks before they can negatively affect a
   rate-limited router control plane component.

5.  Acknowledgements

   The authors would like to thank Ron Bonica for providing initial and
   ongoing review, suggestions, and valuable input.  Pekka Savola,
   Warren Kumari, and Xu Chen provided very thorough and useful feedback
   that improved the document.  Many thanks to John Kristoff,
   Christopher Morrow, and Donald Smith for a fruitful discussion around
   the operational and manageability aspects of router control plane
   protection techniques.  The authors would also like to thank

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   Joel Jaeggli, Richard Graveman, Danny McPherson, Gregg Schudel, Eddie
   Parra, Seo Boon Ng, Manav Bhatia, German Martinez, Wen Zhang, Roni
   Even, Acee Lindem, Glen Zorn, Joe Abley, Ralph Droms, and Stewart
   Bryant for providing thorough review, useful suggestions, and
   valuable input.  Assistance from Jim Bailey and Raphan Han in
   providing technical direction and sample configuration guidance on
   the IPv6 sections was also very much appreciated.  Finally, the
   authors extend kudos to Andrew Yourtchenko for his review, comments,
   and willingness to present this document at IETF 78 (July 2010,
   Maastricht, The Netherlands) on behalf of the authors.

6.  Informative References

   [IP-OPTIONS-FILTER]
              Gont, F. and S. Fouant, "IP Options Filtering
              Recommendations", Work in Progress, February 2010.

   [RFC1812]  Baker, F., Ed., "Requirements for IP Version 4 Routers",
              RFC 1812, June 1995.

   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, May 2000.

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, March 2004.

   [RFC4890]  Davies, E. and J. Mohacsi, "Recommendations for Filtering
              ICMPv6 Messages in Firewalls", RFC 4890, May 2007.

   [RFC5082]  Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
              Pignataro, "The Generalized TTL Security Mechanism
              (GTSM)", RFC 5082, October 2007.

   [RTR-ALERT-CONS]
              Le Faucheur, F., Ed., "IP Router Alert Considerations and
              Usage", Work in Progress, March 2011.

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Appendix A.  Configuration Examples

   The configurations provided below are syntactical representations of
   the semantics described in the document and should be treated as
   non-normative.

A.1.  Cisco Configuration

   Refer to the Control Plane Policing (CoPP) document in the Cisco IOS
   Software Feature Guides (available at <http://www.cisco.com/>) for
   more information on the syntax and options available when configuring
   Control Plane Policing.

   !Start: Protecting The Router Control Plane
   !
   !Control Plane Policing (CoPP) Configuration
   !
   !Access Control List Definitions
   !
   ip access-list extended ICMP
    permit icmp any any
   ipv6 access-list ICMPv6
    permit icmp any any
   ip access-list extended OSPF
    permit ospf 192.0.2.0 0.0.0.255 any
   ipv6 access-list OSPFv3
    permit 89 FE80::/10 any
   ip access-list extended IBGP
    permit tcp 192.0.2.0 0.0.0.255 eq bgp any
    permit tcp 192.0.2.0 0.0.0.255 any eq bgp
   ipv6 access-list IBGPv6
    permit tcp 2001:DB8:1::/48 eq bgp any
    permit tcp 2001:DB8:1::/48 any eq bgp
   ip access-list extended EBGP
    permit tcp host 198.51.100.25 eq bgp any
    permit tcp host 198.51.100.25 any eq bgp
    permit tcp host 198.51.100.27 eq bgp any
    permit tcp host 198.51.100.27 any eq bgp
    permit tcp host 198.51.100.29 eq bgp any
    permit tcp host 198.51.100.29 any eq bgp
    permit tcp host 198.51.100.31 eq bgp any
    permit tcp host 198.51.100.31 any eq bgp

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   ipv6 access-list EBGPv6
    permit tcp host 2001:DB8:100::25 eq bgp any
    permit tcp host 2001:DB8:100::25 any eq bgp
    permit tcp host 2001:DB8:100::27 eq bgp any
    permit tcp host 2001:DB8:100::27 any eq bgp
    permit tcp host 2001:DB8:100::29 eq bgp any
    permit tcp host 2001:DB8:100::29 any eq bgp
    permit tcp host 2001:DB8:100::31 eq bgp any
    permit tcp host 2001:DB8:100::31 any eq bgp
   ip access-list extended DNS
    permit udp 198.51.100.0 0.0.0.252 eq domain any
   ipv6 access-list DNSv6
    permit udp 2001:DB8:100:1::/64 eq domain any
    permit tcp 2001:DB8:100:1::/64 eq domain any
   ip access-list extended NTP
    permit udp 198.51.100.4 255.255.255.252 any eq ntp
   ipv6 access-list NTPv6
    permit udp 2001:DB8:100:2::/64 any eq ntp
   ip access-list extended SSH
    permit tcp 198.51.100.128 0.0.0.128 any eq 22
   ipv6 access-list SSHv6
    permit tcp 2001:DB8:100:3::/64 any eq 22
   ip access-list extended SNMP
    permit udp 198.51.100.128 0.0.0.128 any eq snmp
   ipv6 access-list SNMPv6
    permit udp 2001:DB8:100:3::/64 any eq snmp
   ip access-list extended RADIUS
    permit udp host 198.51.100.9 eq 1812 any
    permit udp host 198.51.100.9 eq 1813 any
    permit udp host 198.51.100.10 eq 1812 any
    permit udp host 198.51.100.10 eq 1813 any
   ipv6 access-list RADIUSv6
    permit udp host 2001:DB8:100::9 eq 1812 any
    permit udp host 2001:DB8:100::9 eq 1813 any
    permit udp host 2001:DB8:100::10 eq 1812 any
    permit udp host 2001:DB8:100::10 eq 1813 any
   ip access-list extended FRAGMENTS
    permit ip any any fragments
   ipv6 access-list FRAGMENTSv6
    permit ipv6 any any fragments
   ip access-list extended ALLOTHERIP
    permit ip any any
   ipv6 access-list ALLOTHERIPv6
    permit ipv6 any any

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RFC 6192              Protect Router Control Plane            March 2011

   !
   !Class Definitions
   !
   class-map match-any ICMP
    match access-group name ICMP
   class-map match-any ICMPv6
    match access-group name ICMPv6
   class-map match-any OSPF
    match access-group name OSPF
    match access-group name OSPFv3
   class-map match-any IBGP
    match access-group name IBGP
    match access-group name IBGPv6
   class-map match-any EBGP
    match access-group name EBGP
    match access-group name EBGPv6
   class-map match-any DNS
    match access-group name DNS
    match access-group name DNSv6
   class-map match-any NTP
    match access-group name NTP
    match access-group name NTPv6
   class-map match-any SSH
    match access-group name SSH
    match access-group name SSHv6
   class-map match-any SNMP
    match access-group name SNMP
    match access-group name SNMPv6
   class-map match-any RADIUS
    match access-group name RADIUS
    match access-group name RADIUSv6
   class-map match-any FRAGMENTS
    match access-group name FRAGMENTS
    match access-group name FRAGMENTSv6
   class-map match-any ALLOTHERIP
    match access-group name ALLOTHERIP
   class-map match-any ALLOTHERIPv6
    match access-group name ALLOTHERIPv6

Dugal, et al.                 Informational                    [Page 15]
RFC 6192              Protect Router Control Plane            March 2011

   !
   !Policy Definition
   !
   policy-map COPP
    class FRAGMENTS
     drop
    class ICMP
     police 500000
        conform-action transmit
        exceed-action drop
        violate-action drop
    class ICMPv6
     police 500000
        conform-action transmit
        exceed-action drop
        violate-action drop
    class OSPF
    class IBGP
    class EBGP
    class DNS
    class NTP
    class SSH
    class SNMP
    class RADIUS
    class ALLOTHERIP
      police cir 500000
        conform-action transmit
        exceed-action drop
        violate-action drop
    class ALLOTHERIPv6
      police cir 500000
        conform-action transmit
        exceed-action drop
        violate-action drop
    class class-default
      police cir 250000
        conform-action transmit
        exceed-action drop
        violate-action drop
   !
   !Control Plane Configuration
   !
   control-plane
    service-policy input COPP
   !
   !End: Protecting The Router Control Plane

Dugal, et al.                 Informational                    [Page 16]
RFC 6192              Protect Router Control Plane            March 2011

A.2.  Juniper Configuration

   Refer to the Firewall Filter Configuration section of the Junos
   Software Policy Framework Configuration Guide (available at
   <http://www.juniper.net/>) for more information on the syntax and
   options available when configuring Junos firewall filters.

   policy-options {
       prefix-list IBGP-NEIGHBORS {
           192.0.2.0/24;
       }
       prefix-list EBGP-NEIGHBORS {
           198.51.100.25/32;
           198.51.100.27/32;
           198.51.100.29/32;
           198.51.100.31/32;
       }
       prefix-list RADIUS-SERVERS {
           198.51.100.9/32;
           198.51.100.10/32;
       }
       prefix-list IBGPv6-NEIGHBORS {
           2001:DB8:1::/48;
       }
       prefix-list EBGPv6-NEIGHBORS {
           2001:DB8:100::25/128;
           2001:DB8:100::27/128;
           2001:DB8:100::29/128;
           2001:DB8:100::31/128;
       }
       prefix-list RADIUSv6-SERVERS {
           2001:DB8:100::9/128;
           2001:DB8:100::10/128;
       }
   }

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RFC 6192              Protect Router Control Plane            March 2011

   firewall {
       policer 500kbps {
           if-exceeding {
               bandwidth-limit 500k;
               burst-size-limit 1500;
           }
           then discard;
       }
       policer 250kbps {
           if-exceeding {
               bandwidth-limit 250k;
               burst-size-limit 1500;
           }
           then discard;
       }
       family inet {
           filter protect-router-control-plane {
               term first-frag {
                   from {
                       first-fragment;
                   }
                   then {
                       count frag-discards;
                       log;
                       discard;
                   }
               }
               term next-frag {
                   from {
                       is-fragment;
                   }
                   then {
                       count frag-discards;
                       log;
                       discard;
                   }
               }
               term icmp {
                   from {
                       protocol icmp;
                   }
                   then {
                       policer 500kbps;
                       accept;
                   }
               }

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RFC 6192              Protect Router Control Plane            March 2011

               term ospf {
                   from {
                       source-address {
                           192.0.2.0/24;
                       }
                       protocol ospf;
                   }
                   then accept;
               }
               term ibgp-connect {
                   from {
                       source-prefix-list {
                           IBGP-NEIGHBORS;
                       }
                       protocol tcp;
                       destination-port bgp;
                   }
                   then accept;
               }
               term ibgp-reply {
                   from {
                       source-prefix-list {
                           IBGP-NEIGHBORS;
                       }
                       protocol tcp;
                       port bgp;
                   }
                   then accept;
               }
               term ebgp-connect {
                   from {
                       source-prefix-list {
                           EBGP-NEIGHBORS;
                       }
                       protocol tcp;
                       destination-port bgp;
                   }
                   then accept;
               }

Dugal, et al.                 Informational                    [Page 19]
RFC 6192              Protect Router Control Plane            March 2011

               term ebgp-reply {
                   from {
                       source-prefix-list {
                           EBGP-NEIGHBORS;
                       }
                       protocol tcp;
                       port bgp;
                   }
                   then accept;
               }
               term dns {
                   from {
                       source-address {
                           198.51.100.0/30;
                       }
                       protocol udp;
                       port domain;
                   }
                   then accept;
               }
               term ntp {
                   from {
                       source-address {
                           198.51.100.4/30;
                       }
                       protocol udp;
                       destination-port ntp;
                   }
                   then accept;
               }
               term ssh {
                   from {
                       source-address {
                           198.51.100.128/25;
                       }
                       protocol tcp;
                       destination-port ssh;
                   }
                   then accept;
               }

Dugal, et al.                 Informational                    [Page 20]
RFC 6192              Protect Router Control Plane            March 2011

               term snmp {
                   from {
                       source-address {
                           198.51.100.128/25;
                       }
                       protocol udp;
                       destination-port snmp;
                   }
                   then accept;
               }
               term radius {
                   from {
                       source-prefix-list {
                           RADIUS-SERVERS;
                       }
                       protocol udp;
                       port [ 1812 1813 ];
                   }
                   then accept;
               }
               term default-term {
                   then {
                       count copp-exceptions;
                       log;
                       policer 500kbps;
                       accept;
                   }
               }
           }
       }

       family inet6 {
           filter protect-router-control-plane-v6 {
               term fragv6 {
                   from {
                       next-header fragment;
                   }
                   then {
                       count frag-v6-discards;
                       log;
                       discard;
                   }
               }

Dugal, et al.                 Informational                    [Page 21]
RFC 6192              Protect Router Control Plane            March 2011

               term icmpv6 {
                   from {
                       next-header icmpv6;
                   }
                   then {
                       policer 500kbps;
                       accept;
                   }
               }
               term ospfv3 {
                   from {
                       source-address {
                           FE80::/10;
                       }
                       next-header ospf;
                   }
                   then accept;
               }
               term ibgpv6-connect {
                   from {
                       source-prefix-list {
                           IBGPv6-NEIGHBORS;
                       }
                       next-header tcp;
                       destination-port bgp;
                   }
                   then accept;
               }
               term ibgpv6-reply {
                   from {
                       source-prefix-list {
                           IBGPv6-NEIGHBORS;
                       }
                       next-header tcp;
                       port bgp;
                   }
                   then accept;
               }
               term ebgpv6-connect {
                   from {
                       source-prefix-list {
                           EBGPv6-NEIGHBORS;
                       }
                       next-header tcp;
                       destination-port bgp;
                   }
                   then accept;
               }

Dugal, et al.                 Informational                    [Page 22]
RFC 6192              Protect Router Control Plane            March 2011

               term ebgpv6-reply {
                   from {
                       source-prefix-list {
                           EBGPv6-NEIGHBORS;
                       }
                       next-header tcp;
                       port bgp;
                   }
                   then accept;
               }
               term dnsv6 {
                   from {
                       source-address {
                          2001:DB8:100:1::/64;
                          }
                       next-header [ udp tcp ];
                       port domain;
                   }
                   then accept;
               }
               term ntpv6 {
                   from {
                       source-address {
                           2001:DB8:100:2::/64;
                       }
                       next-header udp;
                       destination-port ntp;
                   }
                   then accept;
               }
               term sshv6 {
                   from {
                       source-address {
                           2001:DB8:100:3::/64;
                       }
                       next-header tcp;
                       destination-port ssh;
                   }
                   then accept;
               }

Dugal, et al.                 Informational                    [Page 23]
RFC 6192              Protect Router Control Plane            March 2011

               term snmpv6 {
                   from {
                       source-address {
                           2001:DB8:100:3::/64;
                       }
                       next-header udp;
                       destination-port snmp;
                   }
                   then accept;
               }
               term radiusv6 {
                   from {
                       source-prefix-list {
                           RADIUSv6-SERVERS;
                       }
                       next-header udp;
                       port [ 1812 1813 ];
                   }
                   then accept;
               }
               term default-term-v6 {
                   then {
                       policer 500kbps;
                       count copp-exceptions-v6;
                       log;
                       accept;
                   }
               }
           }
       }

       family any {
           filter protect-router-control-plane-non-ip {
               term rate-limit-non-ip {
                   then {
                       policer 250kbps;
                       accept;
                   }
               }
           }
       }
   }

Dugal, et al.                 Informational                    [Page 24]
RFC 6192              Protect Router Control Plane            March 2011

   interfaces {
       lo0 {
           unit 0 {
               family inet {
                   filter input protect-router-control-plane;
               }
               family inet6 {
                   filter input protect-router-control-plane-v6;
               }
               family any {
                   filter input protect-router-control-plane-non-ip;
               }
           }
       }
   }

Authors' Addresses

   Dave Dugal
   Juniper Networks
   10 Technology Park Drive
   Westford, MA  01886
   US

   EMail: dave@juniper.net

   Carlos Pignataro
   Cisco Systems
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   EMail: cpignata@cisco.com

   Rodney Dunn
   Cisco Systems
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   EMail: rodunn@cisco.com

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