Service Chaining using Virtual Networks with BGP
draft-fm-bess-service-chaining-01
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Rex Fernando , Stuart Mackie , Dhananjaya Rao , Bruno Rijsman , Maria Napierala | ||
| Last updated | 2015-07-20 (Latest revision 2015-07-06) | ||
| Replaces | draft-rfernando-bess-service-chaining, draft-mackie-sfc-using-virtual-networking | ||
| Replaced by | draft-ietf-bess-service-chaining, draft-ietf-bess-service-chaining | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
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| Send notices to | (None) |
draft-fm-bess-service-chaining-01
INTERNET-DRAFT R. Fernando
Intended Status: Informational Cisco
Expires: January 6, 2016 S. Mackie
Juniper
D. Rao
Cisco
B. Rijsman
Juniper
M. Napierala
AT&T
July 5, 2015
Service Chaining using Virtual Networks with BGP
draft-fm-bess-service-chaining-01
Abstract
This document describes how service function chains (SFC) can be
applied to traffic flows using routing in a virtual (overlay) network
to steer traffic between service nodes. Chains can include services
running in routers, on physical appliances or in virtual machines.
Service chains have applicability at the subscriber edge, business
edge and in multi-tenant datacenters. The routing function into SFCs
and between service functions within an SFC can be performed by
physical devices (routers), be virtualized inside hypervisors, or run
as part of a host OS.
A BGP control plane for route distribution is used to create virtual
networks implemented using IP MPLS, VXLAN or other suitable
encapsulation, where the routes within the virtual networks cause
traffic to flow through a sequence of service nodes that apply packet
processing functions to the flows. Two techniques are described: in
one the service chain is implemented as a sequence of distinct VPNs
between sets of service nodes that apply each service function; in
the other, the routes within a VPN are modified through the use of
special route targets and modified next-hop resolution to achieve the
desired result.
In both techniques, service chains can be created by manual
configuration of routes and route targets in routing systems, or
through the use of a controller which contains a topological model of
the desired service chains.
This document also contains discussion of load balancing between
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network functions, symmetric forward and reverse paths when stateful
services are involved, and use of classifiers to direct traffic into
a service chain.
Status of this Memo
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Copyright and License Notice
Copyright (c) 2015 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
publication of this document. Please review these documents
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described in the Simplified BSD License.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Service Function Chain Architecture Using Virtual Networking . 8
2.1 High Level Architecture . . . . . . . . . . . . . . . . . . 8
2.2 Service Function Chain Logical Model . . . . . . . . . . . . 10
2.3 Service Function Implemented in a Set of SF Instances . . . 10
2.4 SF Instance Connections to VRFs . . . . . . . . . . . . . . 12
2.4.1 SF Instance in Physical Appliance . . . . . . . . . . . 12
2.4.2 SF Instance in a Virtualized Environment . . . . . . . . 12
2.5 Encapsulation Tunneling for Transport . . . . . . . . . . . 13
2.6 SFC Creation Procedure . . . . . . . . . . . . . . . . . . . 14
2.6.1 SFC Provisioning Using Sequential VPNs . . . . . . . . . 14
2.6.2 Modified-Route SFC Creation . . . . . . . . . . . . . . 16
2.7 Controller Function . . . . . . . . . . . . . . . . . . . . 18
2.8 Variations on Setting Prefixes in an SFC . . . . . . . . . . 18
2.8.1 Variation 1 . . . . . . . . . . . . . . . . . . . . . . 18
2.8.2 Variation 2 . . . . . . . . . . . . . . . . . . . . . . 19
2.9 Header Transforming Service Functions . . . . . . . . . . . 19
3 Load Balancing Along a Service Function Chain . . . . . . . . . 20
3.1 SF Instances Connected to Separate VRFs . . . . . . . . . . 20
3.2 SF Instances Connected to the Same VRF . . . . . . . . . . . 21
3.3 Combination of Egress and Ingress VRF Load Balancing . . . . 21
3.4 Forward and Reverse Flow Load Balancing . . . . . . . . . . 23
3.4.1 Issues with Equal Cost Multi-Path Routing . . . . . . . 23
3.4.2 Modified ECMP with Consistent Hash . . . . . . . . . . . 23
3.4.3 ECMP with Flow Table . . . . . . . . . . . . . . . . . . 24
4 Steering into SFCs Using a Classifier . . . . . . . . . . . . . 25
5 External Domain Co-ordination . . . . . . . . . . . . . . . . . 26
6 Fine-grained steering using BGP Flow-Spec . . . . . . . . . . . 27
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7 BGP-EVPN signaling . . . . . . . . . . . . . . . . . . . . . . 27
8 Controller Federation . . . . . . . . . . . . . . . . . . . . . 27
9 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 27
10 Security Considerations . . . . . . . . . . . . . . . . . . . 27
11 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
12 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
13 References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
13.1 Normative References . . . . . . . . . . . . . . . . . . . 29
13.2 Informative References . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32
1 Introduction
The purpose of networks is to allow computing systems to communicate
with each other. Requests are usually made from the client or
customer side of a network, and responses are generated by
applications residing in a datacenter. Over time, the network between
the client and the application has become more complex, and traffic
between the client and the application is acted on by intermediate
systems that apply network services. Some of these activities, like
firewall filtering, subscriber attachment and network address
translation are generally carried out in network devices along the
traffic path, while others are carried out by dedicated appliances,
such as media proxy and deep packet inspection (DPI). Deployment of
these in-network services is complex, time-consuming and costly,
since they require configuration of devices with vendor-specific
operating systems, sometimes with co-processing cards, or deployment
of physical devices in the network, which requires cabling and
configuration of the devices that they connect to. Additionally,
other devices in the network need to be configured to ensure that
traffic is correctly steered through the systems that services are
running on. The current mode of operations does not easily allow
common operational processes to be applied to the lifecycle of
services in the network, or for steering of traffic through them. The
recent emergence of Network Functions Virtualization (NFV) [NFVE2E]
to provide a standard deployment model for network services as
software appliances, combined with Software Defined Networking (SDN)
for more dynamic traffic steering can provide foundational elements
that will allow network services to be deployed and managed far more
efficiently and with more agility than is possible today. This
document describes how the combination of several existing
technologies can be used to create chains of functions, while
preserving the requirements of scale, performance and reliability for
service provider networks. The technologies employed are:
o Traffic flow between service functions described by routing and
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network policies rather than by static physical or logical
connectivity
o Packet header encapsulation in order to create virtual private
networks using network overlays
o VRFs on both physical devices and in hypervisors to implement
forwarding policies that are specific to each virtual network
o Optional use of a controller to calculate routes to be installed in
routing systems to form a service chain. The controller uses a
topological model that stores service function instance connectivity
to network devices and intended connectivity between service
functions.
o MPLS or other labeling to facilitate identification of the next
interface to send packets to in a service function chain
o BGP or BGP-style signaling to distribute routes in order to create
service function chains
o Distributed load balancing between service functions performed in
the VRFs that service function instance connect to.
Virtualized environments can be supported without necessarily running
BGP or MPLS natively. Messaging protocols such as NC/YANG, XMPP or
OpenFlow may be used to signal forwarding information. Encapsulation
mechanisms such as VXLAN or GRE may be used for overlay transport.
The term "BGP-style", above, refers to this type of signaling.
Traffic can be directed into service function chains using IP routing
at each end of the service function chain, or be directed into the
chain by a classifier function that can determine which service chain
a traffic flow should pass through based on deep packet inspection
(DPI) and/or subscriber identity.
The techniques can support an evolution from services implemented in
physical devices attached to physical forwarding systems (routers) to
fully virtualized implementations as well as intermediate hybrid
implementations.
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1.1 Terminology
This document uses the following acronyms and terms.
Terms Meaning
----- --------------------------------------------------
AS Autonomous System
ASBR Autonomous System Border Router
CE Customer Edge
FW Firewall
I2RS Interface to the Routing System
L3VPN Layer 3 VPN
LB Load Balancer
NLRI Network Layer Reachability Information [RFC4271]
P Provider backbone router
proxy-arp proxy-Address Resolution Protocol
RR Route Reflector
RT Route Target
SDN Software Defined Network
vCE virtual Customer Edge router
vFW virtual Firewall
vLB virtual Load Balancer
VM Virtual Machine
vPC virtual Private Cloud
vPE virtual Provider Edge router
VPN Virtual Private Network
VRF VPN Routing and Forwarding table [RFC4364]
vRR virtual Route Reflector
This document follows some of the terminology used in [draft-ietf-
sfc-architecture] and adds some new terminology:
Network Service:
An externally visible service offered by a network operator; a
service may consist of a single service function or a composite
built from several service functions executed in one or more pre-
determined sequences and delivered by software executing in
physical or virtual devices
Classification:
Customer/network/service policy used to identify and select
traffic flow(s) requiring certain outbound forwarding actions, in
particular, to direct specific traffic flows into the ingress of a
particular service function chain, or causing branching within a
service function chain.
Virtual Network:
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A logical overlay network built using virtual links or packet
encapsulation, over an existing network (the underlay).
Service Function Chain (SFC):
A service function chain defines an ordered set of service
functions that must be applied to packets and/or frames selected
as a result of classification. An SFC may be either a linear chain
or a complex service graph with multiple branches. The term
"Service Chain" is often used in place of "Service Function
Chain".
SFC Set:
The pair of SFCs through which the forward and reverse directions
of a given classified flow will pass.
Service Function (SF):
A logical function that is applied to packets. A service function
can act at the network layer or other OSI layers. A service
function can be embedded in one or more physical network elements,
or can be implemented in one or more software instances running on
physical or virtual hosts. One or multiple service functions can
be embedded in the same network element or run on the same host.
Multiple instances of a service function can be enabled in the
same administrative domain. We will also refer to "Service
Function" as, simply, "Service" for simplicity.
A non-exhaustive list of services includes: firewalls, DDOS
protection, anti-malware/ant-virus systems, WAN and application
acceleration, Deep Packet Inspection (DPI), server load balancers,
network address translation, HTTP Header Enrichment functions,
video optimization, TCP optimization, etc.
SF Instance:
An instance of software that implements the packet processing of a
service function
SF Instance Set:
A group of SF instances that, in parallel, implement a service
function in an SFC. Routing System: A hardware or software system
that performs layer 3 routing and/or forwarding functions. The
term includes physical routers as well as hypervisor or Host OS
implementations of the forwarding plane of a conventional router.
VRF:
A subsystem within a routing system as defined in [RFC4364] that
contains private routing and forwarding tables and has physical
and/or logical interfaces associated with it. In the case of
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hypervisor/Host OS implementations, the term refers only to the
forwarding function of a VRF, and this will be referred to as a
"VPN forwarder."
Ingress VRF:
A VRF containing an ingress interface of a SF instance
Egress VRF:
A VRF containing an egress interface of a SF instance
2 Service Function Chain Architecture Using Virtual Networking
The techniques described in this document use virtual networks to
implement service function chains. Service function chains can be
implemented on devices that support existing MPLS VPN and BGP
standards [RFC4364, RFC4271, RFC4760], but other encapsulations, such
as VXLAN [RFC7348], can be used. Similarly, equivalent control plane
protocols such as BGP-EVPN can also be used where supported.
The following sections detail the building blocks of the SFC
architecture, and outline the processes of route installation and
subsequent route exchange to create an SFC.
2.1 High Level Architecture
Service function chains can be deployed with or without a classifier.
Use cases where SFCs may be deployed without a classifier include
multi-tenant data centers, private and public cloud and virtual CPE
for business services. Classifiers will primarily be used in mobile
and wireline subscriber edge use cases. Use of a classifier is
discussed in Section 4.
A high-level architecture diagram of an SFC without a classifier,
where traffic is routed into and out of the SFC, is shown in Figure
1, below. An optional controller is shown that contains a topological
model of the SFC and which configures the network resources to
implement the SFC.
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+-------------------------+
|--- Data plane connection|
|=== Encapsulation tunnel |
| O VRF |
+-------------------------+
Control +------------------------------------------------+
Plane | Controller |
....... +-+------------+----------+----------+---------+-+
| | | | |
Service | +---+ | +---+ | +---+ | |
Plane | |SF1| | |SF2| | |SF3| | |
| +---+ | +---+ | +---+ | |
....... / | | / | | / | | / /
+-----+ +--|-|--+ +--|-|--+ +--|-|--+ +-----+
| | | | | | | | | | | | | | | |
Net-A-->---O==========O O========O O========O O=========O---->Net-B
| | | | | | | | | |
Data | R-A | | R-1 | | R-2 | | R-3 | | R-B |
Plane +-----+ +-------+ +-------+ +-------+ +-----+
^ ^ ^ ^
| | | |
| Ingress Egress |
| VRF VRF |
SFC Entry SFC Exit
VRF VRF
Figure 1 - High level SFC Architecture
Traffic from Network-A destined for Network-B will pass through the
SFC composed of SF instances, SF1, SF2 and SF3. Routing system R-A
contains a VRF (shown as "O" symbol) that is the SFC entry point.
This VRF will advertise a route to reach Network-B into Network-A
causing any traffic from a source in Network-A with a destination in
Network-B to arrive in this VRF. The forwarding table in the VRF in
R-A will direct traffic destined for Network-B into an encapsulation
tunnel with destination R-1 and a label that identifies the ingress
(left) interface of SF1 that R-1 should send the packets out on. The
packets are processed by service instance SF-1 and arrive in the
egress (right) VRF in R-1. The forwarding entries in the egress VRF
direct traffic to the next ingress VRF using encapsulation tunneling.
The process is repeated for each service instance in the SFC until
packets arrive at the SFC exit VRF (in R B). This VRF is peered with
Network-B and routes packets towards their destinations in the user
data plane.
In the example, each pair of ingress and egress VRFs are configured
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in separate routing systems, but such pairs could be collocated in
the same routing system, and it is possible for the ingress and
egress VRFs for a given SF instance to be in different routing
systems. The SFC entry and exit VRFs can be collocated in the same
routing system, and the service instances can be local or remote from
either or both of the routing systems containing the entry and exit
VRFs, and from each other.
The controller is responsible for configuring the VRFs in each
routing system, installing the routes in each of the VRFs to
implement the SFC, and, in the case of virtualized services, may
instantiate the service instances.
2.2 Service Function Chain Logical Model
A service function chain is a set of logically connected service
functions through which traffic can flow. Each egress interface of
one service function is logically connected to an ingress interface
of the next service function.
+------+ +------+ +------+
Network-A-->| SF-1 |-->| SF-2 |-->| SF-3 |-->Network-B
+------+ +------+ +------+
Figure 2 - A Chain of Service Functions
In Figure 2, above, a service function chain has been created that
connects Network-A to Network-B, such that traffic from a host in
Network-A to a host in Network-B will traverse the service function
chain.
As defined in [draft-ietf-sfc-architecture], a service function chain
can be uni-directional or bi-directional. In this document, in order
to allow for the possibility that the forward and reverse paths may
not be symmetrical, SFCs are defined as uni-directional, and the term
"SFC set" is used to refer to a pair of forward and reverse direction
SFCs for some set of routed or classified traffic.
2.3 Service Function Implemented in a Set of SF Instances
A service function instance is a software system that acts on packets
that arrive on an ingress interface of that software system. Service
function instances may run on a physical appliance or in a virtual
machine. A service function instance may be transparent at layer 2
and/or 3, and may support branching across multiple egress interfaces
and may support aggregation across ingress interfaces. For
simplicity, the examples in this document have a single ingress and a
single egress interface.
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Each service function in a chain can be implemented by a single
service function instance, or by a set of instances in order to
provide scale and resilience.
+------------------------------------------------------------------+
| Logical Service Functions Connected in a Chain |
| |
| +--------+ +--------+ |
| Net-A--->| SF-1 |----------->| SF-2 |--->Net-B |
| +--------+ +--------+ |
| |
+------------------------------------------------------------------+
| Service Function Instances Connected by Virtual Networks |
| ...... ...... |
| : : +------+ : : |
| : :-->|SFI-11|-->: : ...... |
| : : +------+ : : +------+ : : |
| : : : :-->|SFI-21|-->: : |
| : : +------+ : : +------+ : : |
| A->: VN-1 :-->|SFI-12|-->: VN-2 : : VN-3 :-->B |
| : : +------+ : : +------+ : : |
| : : : :-->|SFI-22|-->: : |
| : : +------+ : : +------+ : : |
| : :-->|SFI-13|-->: : '''''' |
| : : +------+ : : |
| '''''' '''''' |
+------------------------------------------------------------------+
Figure 3 - Service Functions Are Composed of SF Instances
Connected Via Virtual Networks
In Figure 3, service function SF-1 is implemented in three service
function instances, SFI-11, SFI-12, and SFI-13. Service function SF-2
is implemented in two SF instances. The service function instances
are connected to the next service function in the chain using a
virtual network, VN-2. Additionally, a virtual network (VN-1) is used
to enter the SFC and another (VN-3) is used at the exit.
The logical connection between two service functions is implemented
using a virtual network that contains egress interfaces for instances
of one service function, and ingress interfaces of instances of the
next service function. Traffic is directed across the virtual network
between the two sets of service function instances using layer 3
forwarding (e.g. an MPLS VPN) or layer 2 forwarding (e.g. a VXLAN).
The virtual networks could be described as "directed half-mesh", in
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that the egress interface of each SF instance of one service function
can reach any ingress interface of the SF instances of the connected
service function.
Details on how routing across virtual networks is achieved, and
requirements on load balancing across ingress interfaces are
discussed in later sections of this document.
2.4 SF Instance Connections to VRFs
SF instances can be deployed as software running on physical
appliances, or in virtual machines running on a hypervisor. These two
options are described in more detail in the following sections.
2.4.1 SF Instance in Physical Appliance
The case of a SF instance running on a physical appliance is shown in
Figure 4, below.
+---------------------------------+
| |
| +-----------------------------+ |
| | Service Function Instance | |
| +-------^-------------|-------+ |
| | Host | |
+---------|-------------|---------+
| |
+------ |-------------|-------+
| | | |
| +----|----+ +-----v----+ |
---------+ Ingress | | Egress +---------
---------> VRF | | VRF ---------->
---------+ | | +---------
| +---------+ +----------+ |
| Routing System |
+-----------------------------+
Figure 4 - Ingress and Egress VRFs for a Physical Routing System
and Physical SF Instance
The routing system is a physical device and the service function
instance is implemented as software running in a physical appliance
(host) connected to it. Transport between VRFs on different routing
systems that are connected to other SF instances in an SFC is via
encapsulation tunnels, such as MPLS over GRE, or VXLAN.
2.4.2 SF Instance in a Virtualized Environment
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In virtualized environments, a routing system with VRFs that act as
VPN forwarders is resident in the hypervisor/Host OS, and is co-
resident in the host with one or more SF instances that run in
virtual machines. The egress VPN forwarder performs tunnel
encapsulation to send packets to other physical or virtual routing
systems with attached SF instances to form an SFC. The tunneled
packets are sent through the physical interfaces of the host to the
other hosts or physical routers. This is illustrated in Figure 5,
below.
+-------------------------------------+
| +-----------------------------+ |
| | Service Function Instance | |
| +-------^-------------|-------+ |
| | | |
| +---------|-------------|---------+ |
| | +-------|-------------|-------+ | |
| | | | | | | |
| | | +----|----+ +-----v----+ | | |
------------+ Ingress | | Egress +-----------
------------> VRF | | VRF ------------>
------------+ | | +-----------
| | | +---------+ +----------+ | | |
| | | Routing System | | |
| | +-----------------------------+ | |
| | Hypervisor or Host OS | |
| +---------------------------------+ |
| Host |
+-------------------------------------+
Figure 5 - Ingress and Egress VRFs for a Virtual Routing
System and Virtualized SF Instance
When more than one instance of an SF is running on a hypervisor, they
can be connected to the same VRF for scale out of an SF within an
SFC.
The routing mechanisms in the VRFs into and between service function
instances, and the encapsulation tunneling between routing systems
are identical in the physical and virtual implementation of SFCs
described in this document. Physical and virtual service functions
can be mixed as needed with different combinations of physical and
virtual routing systems.
2.5 Encapsulation Tunneling for Transport
Encapsulation tunneling is used to transport packets between SF
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instances in the chain and, when a classifier is not used, from the
originating network into the SFC and from the SFC into the
destination network.
The tunnels can be MPLS over GRE [RFC4023], MPLS over UDP [draft-
ietf-mpls-in-udp], MPLS over MPLS [RFC3031], VXLAN [RFC7348], or
another suitable encapsulation method.
Tunneling may be enabled in each routing system as part of a base
configuration or may be configured by the controller. Tunnel
encapsulations may be configured by the controller or signaled using
BGP.
2.6 SFC Creation Procedure
This section describes how service chains are created using two
methods:
o Sequential VPNs - where a conventional VPN is created between each
set of SF instances to create the links in the SFC
o Route Modification - where each routing system modifies advertised
routes that it receives, to realize the links in an SFC on the basis
of a special service topology RT and a route-policy that describes
the service chain logical topology
In both cases the controller, when present, is responsible for
creating ingress and egress VRFs, configuring the interfaces
connected to SF instances in each VRF and configuring RTs for each
VRF. Additionally, in the second method, the controller also sends
the route-policy containing the service chain logical topology to
each routing system. If a controller is not used, these procedures
will require to be performed manually or through scripting, for
instance.
The following sub-sections describe how RT configuration, local route
installation and route distribution occurs in each of the methods.
2.6.1 SFC Provisioning Using Sequential VPNs
The task of the controller in this method of SFC provisioning is to
create a set of VPNs that carry traffic to the destination network
through instances of each service function in turn. This is achieved
by configuring RTs such that the egress VRFs of one set of SF
instances import an RT that is an export RT for the ingress VRFs of
the next, logically connected, set of SF instances.
The process of SFC creation is as follows
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1. Controller creates a VRF in each routing system that is
connected to a service instance that will be used in the SFC
2. Controller configures each VRF to contain the logical interface
that connects to a SF instance.
3. Controller implements route target import and export policies
in the VRFs using the same route targets for the egress VRFs of a
service function and the ingress VRFs of the next logically
connected service function in the SFC.
4. Controller installs a static route in each ingress VRF whose
next hop is the interface that a SF instance is connected to. The
prefix for the route is the destination network to be reached by
passing through the SFC.
5. Routing systems advertise the static routes via BGP as VPN
routes with next hop being the IP address of the router, with an
encapsulation specified and a label that identifies the service
instance interface.
6. Routing systems containing VRFs with matching route targets
receive the updates.
7. Routes are installed in egress VRFs with matching import
targets. The egress VRFs of each SF instance will now contain VPN
routes to one or more routers containing ingress VRFs for SF
instances of the next service function in the SFC.
In the case of physical routers, the creation and configuration of
VRFs, interfaces and local static routes can be performed
programmatically using Netconf; and BGP route distribution can use a
route reflector (which may be part of the controller). In the
virtualized case, where a VPN forwarder is present, creation and
configuration of VRFs, interfaces and installation of routes can be
performed using a single protocol like XMPP, NC/YANG or an equivalent
programmatic interface.
Also in the virtualized case, routes in the ingress and egress VRFs
can be calculated by the controller based on its internal knowledge
of the required SFC topology and the connectivity of SF instances to
routing systems. In this case the routes are directly installed and
no route advertisement is necessary.
As discussed further in Section 3, egress VRFs can load balance
across the multiple next hops advertised from the next set of ingress
VRFs.
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Routes to the destination network via the first set of SF instances
are advertised to the gateway router for the source network, and the
egress VRFs of the last SF instance set have routes via the
destination network gateway router.
2.6.2 Modified-Route SFC Creation
In this method of SFC configuration, all the VRFs connected to SF
instances are configured with same import and export RT, so they form
a VPN-connected mesh between the SF instance interfaces. This is
termed the "Service VPN". A route is configured or learnt in each VRF
with destination being the IP address of the connected SF instance
via an interface configured in the VRF. The interface may be a
physical or logical interface. The routing system that hosts such a
VRF advertises a VPN route for each locally connected SF instance,
with a forwarding label that enables it to forward incoming traffic
from other routing systems to the connected SF instance. The VPN
routes may be advertised via an RR or the controller, which then
sends these updates to all the other routing systems that have VRFs
with the service VPN RT. At this point all the VRFs have a route to
reach every SF instance. The same IP address is used for each SF
instance in a set, enabling load-balancing among multiple SF
instances in the set.
The controller sends a route-policy to each routing system in the
VPN, that describes the logical topology of each service chain that
it belongs to. The route-policy contains entries in the form of a
tuple for each service chain:
{Service-topology-name, Service-topology-RT, Service-node-
sequence} where Service-node-sequence is simply an ordered list of
the service function instance IP addresses that are in the chain.
Every service function chain has a single unique service-topology-RT
that is provisioned on all participating routing systems in the
relevant VRFs.
The VRF in the routing system that connects to the destination
network is configured to attach the Service-topology-RT to exported
routes, and the VRF in the gateway router of the source network will
import routes using Service-topology-RT. A controller may also be
used to originate the Service-topology-RT attached routes.
Route-policies may be described in a variety of formats in addition
to that described above. For instance, it would be possible to use
YANG as a modeling language.
Using Figure 1 for reference, when the gateway R-B advertises a VPN
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route to Network-B, it attaches the Service-topology-RT. BGP route
updates are sent to all the routing systems in the service VPN. The
routing systems perform a modified set of actions for next-hop
resolution and route installation in the ingress VRFs compared to
normal BGP VPN behavior in routing systems, but no changes are
required in the operation of the BGP protocol itself. The
modification of behavior in the routing systems allows the automatic
and constrained flow of traffic through the service chain.
Each routing system in the service VPN will process the VPN route to
Network-B via R-B as follows:
1. If the routing system contains VRFs that import the Service-
topology-RT, continue, otherwise ignore the route.
2. The routing system identifies the position and role
(ingress/egress) of each of its VRFs in the SFC by comparing the
IP address of the route in the VRF to the connected SF instance
with those in the Service-node-sequence in the route-policy.
Alternatively, the controller may provision the specific service
node IP to be used as the next-hop in each VRF, in the route-
policy.
3. The routing system modifies the next-hop of the imported route
with the Service-topology-RT, to select the appropriate next-hop
as per the route-policy. It ignores the next-hop and label in the
received route. It resolves the selected next-hop in the VRF
routing table.
a. The imported route to Network-B in the ingress VRF is
modified to have a next-hop of the IP address of the logically
connected SF instance.
b. The imported route to Network-B in the egress VRF is
modified to have a next hop of the IP address of the next SF
instance in the SFC.
4. The egress VRFs for the last service function install the VPN
route via the gateway R-B unmodified.
Note that the modified routes are not re-advertised into the VPN by
the various routing systems in the SFC.
Similar to the sequential VPN method, VRF configuration and creation,
and routing-policy installation can be performed manually or via
scripting, or a controller could be used to automate the process.
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2.7 Controller Function
The purpose of the controller is to manage instantiation of SFCs in
networks and datacenters. When an SFC is to be instantiated, a model
of the desired topology (service functions, number of instances,
connectivity) is built in the controller either via an API or GUI.
The controller then selects resources in the infrastructure that will
support the SFC and configures them. This can involve instantiation
of SF instances to implement each service function, the instantiation
of VRFs that will form virtual networks between SF instances, and
installation of routes to cause traffic to flow into and between SF
instances.
For simplicity, in this document, the controller is assumed to
contain all the required features for management of SFCs. In actual
implementations, these features may be distributed among multiple
inter-connected systems. E.g. An overarching orchestrator might
manage the overall SFC model, sending instructions to a separate
virtual machine manager to instantiate service function instances,
and to a virtual network manager to set up the service chain
connections between them.
The controller can also perform necessary BGP signaling and route
distribution actions as described throughout this document.
2.8 Variations on Setting Prefixes in an SFC
2.8.1 Variation 1
In the configuration methods described above, the network prefixes
for each network (Network-A and Network-B in the example above)
connected to the SFC are used in the routes that direct traffic
through the SFC. This creates an operational linkage between the
implementation of the SFC and the insertion of the SFC into a
network.
For instance, subscriber network prefixes will normally be segmented
across subscriber attachment points such as broadband or mobile
gateways. This means that each SFC would have to be configured with
the subscriber network prefixes whose traffic it is handling.
In a variation of the SFC configuration method described above, the
prefixes used in each direction can be such that they include all
possible addresses at each side of the SFC. For example, in Figure 1,
the prefix for Network-A could include all subscriber IP addresses
and the prefix for Network-B could be the default route, 0/0.
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Using this technique, the same routes can be installed in all
instances of an SFC that serve different groups of subscribers in
different geographic locations.
The routes forwarding traffic into a SF instance and to the next SF
instance are installed when an SFC is initially built, and each time
a SF instance is connected into the SFC, but there is no requirement
for VRFs to be reconfigured when traffic from different networks pass
through the service chain, so long as their prefix is included in the
prefixes in the VRFs along the SFC.
In this variation, it is assumed that no subscriber-originated
traffic will enter the SFC destined for an IP address also in the
subscriber network address range. This will not be a restriction in
many cases.
2.8.2 Variation 2
As another slight variation of the above, a network prefix may be
disaggregated and spread out among various gateway routers, for
instance, in the case of virtual machines in a data-center. In order
to reduce the scaling requirements on the routing systems along the
SFC, the aggregate network prefix may be advertised with the Service-
topology-RT and used in the traffic forwarding along the SFC.
Where there is a gateway router for the destination network that can
aggregate the prefixes, none of the routing systems along the SFC
need to receive the more-specific routes. If there is not, the
service chain can be divided into two parts such that only the egress
VRFs of the last SF instance import the more specific routes; and the
rest of the VRFs only import the aggregate prefix. For instance, this
may be done by using two different Service-topology-RTs for more-
specific and aggregate routes.
In the simplest case, a default route is used to direct forwarding
along the SFC upto the last SF instance, while the source network's
gateway routers and the egress VRF of the last SF instance use the
destination network's prefixes.
2.9 Header Transforming Service Functions
If a service function performs an action that changes the source
address in the packet header (e.g., NAT), the routes that were
installed as described above may not support reverse flow traffic.
The solution to this is for the controller modify the routes in the
reverse direction to direct traffic into instances of the
transforming service function. The original routes with a source
prefix (Network-A in Figure 2) are replaced with a route that has a
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prefix that includes all the possible addresses that the source
address could be mapped to. In the case of network address
translation, this would correspond to the NAT pool.
3 Load Balancing Along a Service Function Chain
One of the key concepts driving NFV [NFVE2E]is the idea that each
service function along an SFC can be separately scaled by changing
the number of service function instances that implement it. This
requires that load balancing be performed before entry into each
service function. In this architecture, load balancing is performed
in either or both of egress and ingress VRFs depending on the type of
load balancing being performed, and if more than one service instance
is connected to the same ingress VRF.
3.1 SF Instances Connected to Separate VRFs
If SF instances implementing a service in an SFC are each connected
to separate VRFs(e.g. instances are connected to different routers or
are running on different hosts), load balancing is performed in the
egress VRFs of the previous service, or in the VRF that is the entry
to the SFC. The controller distributes BGP multi-path routes to the
egress VRFs. The destination prefix of each route is the ultimate
destination network, or its representative aggregate or default. The
next-hops in the ECMP set are BGP next-hops of the service instances
attached to ingress VRFs of the next service in the SFC. The load
balancing corresponds to BGP Multipath, which requires that the route
distinguishers for each route are distinct in order to recognize that
distinct paths should be used. Hence, each VRF in a distributed, SFC
environment should have a unique route distinguisher.
+------+ +-------------------------+
O----|SFI-11|---O |--- Data plane connection|
// +------+ \\ |=== Encapsulation tunnel |
// \\ | O VRF |
// \\ | * Load balancer |
// \\ +-------------------------+
// +------+ \\
Net-A-->O*====O----|SFI-12|---O====O-->Net-B
\\ +------+ //
\\ //
\\ //
\\ //
\\ +------+ //
O----|SFI-13|---O
+------+
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Figure 6 - Load Balancing across SF Instances Connected
to Different VRFs
In the diagram, above, a service function is implemented in three
service instances each connected to separate VRFs. Traffic from
Network-A arrives at VRF at the start of the SFC, and is load
balanced across the service instances using a set of ECMP routes with
next hops being the addresses of the routing systems containing the
ingress VRFs and with labels that identify the ingress interfaces of
the service instances.
3.2 SF Instances Connected to the Same VRF
When SF instances implementing a service in an SFC are connected to
the same ingress VRF, load balancing is performed in the ingress VRF
across the service instances connected to it. The controller will
install routes in the ingress VRF to the destination network with the
interfaces connected to each service instance as next hops. The
ingress VRF will then use ECMP to load balance across the service
instances.
+------+ +-------------------------+
|SFI-11| |--- Data plane connection|
+------+ |=== Encapsulation tunnel |
/ \ | O VRF |
/ \ | * Load balancer |
/ \ +-------------------------+
/ +------+ \
Net-A-->O====O*----|SFI-12|----O====O-->Net-B
\ +------+ /
\ /
\ /
\ /
+------+
|SFI-13|
+------+
Figure 7 - Load Balancing across SF Instances Connected to
the Same VRF
In the diagram, above, a service is implemented by three service
instances that are connected to the same ingress and egress VRFs. The
ingress VRF load balances across the ingress interfaces using ECMP,
and the egress traffic is aggregated in the egress VRF.
3.3 Combination of Egress and Ingress VRF Load Balancing
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In Figure 8, below, an example SFC is shown where load balancing is
performed in both ingress and egress VRFs.
+-------------------------+
|--- Data plane connection|
+------+ |=== Encapsulation tunnel |
|SFI-11| | O VRF |
+------+ | * Load balancer |
/ \ +-------------------------+
/ \
/ +------+ \ +------+
O*---|SFI-12|---O*====O---|SFI-21|---O
// +------+ \\ // +------+ \\
// \\// \\
// \\ \\
// //\\ \\
// +------+ // \\ +------+ \\
Net-A-->O*====O----|SFI-13|---O*====O---|SFI-22|---O====O-->Net-B
+------+ +------+
^ ^ ^ ^ ^ ^
| | | | | |
| Ingress Egress | | |
| Ingress Egress |
SFC Entry SFC Exit
Figure 8 - Load Balancing across SF Instances
In Figure 8, above, an SFC is composed of two services implemented by
three service instances and two service instances, respectively. The
service instances SFI-11 and SFI-12 are connected to the same ingress
and egress VRFs, and all the other service instances are connected to
separate VRFs.
Traffic entering the SFC from Network-A is load balanced across the
ingress VRFs of the first service function by the chain entry VRF,
and then load balanced again across the ingress interfaces of SFI-11
and SFI-12 by the shared ingress VRF. Note that use of standard ECMP
will lead to an uneven distribution of traffic between the three
service instances (25% to SFI-11, 25% to SFI-12, and 50% to SFI-13).
This issue can be mitigated through the use of BGP link bandwidth
extended community [draft-ietf-idr-link-bandwidth].
After traffic passes through the first set of service instances, it
is load balanced in each of the egress VRFs of the first set of
service instances across the ingress VRFs of the next set of service
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instances.
3.4 Forward and Reverse Flow Load Balancing
This section discusses requirements in load balancing for forward and
reverse paths when stateful service functions are deployed.
3.4.1 Issues with Equal Cost Multi-Path Routing
As discussed in the previous sections, load balancing in the forward
SFC in the above example can automatically occur with standard BGP,
if multiple equal cost routes to Network-B are installed into all the
ingress VRFs, and each route directs traffic through a different
service function instance in the next set. The multiple BGP routes in
the routing table will translate to Equal Cost Multi-Path in the
forwarding table. The hash used in the load balancing algorithm (per
packet, per flow or per prefix) is implementation specific.
If a service function is stateful, it is required that forward flows
and reverse flows always pass through the same service function
instance. ECMP does not provide this capability, since the hash
calculation will see different input data for the same flow in the
forward and reverse directions (since the source and destination
fields are reversed).
Additionally, if the number of SF instances changes, either
increasing to expand capacity, or decreases (planned, or due to a SF
instance failure), the hash table in ECMP is recalculated, and most
flows will be directed to a different SF instance and user sessions
will be disrupted.
There are a number of ways to satisfy the requirements of symmetric
forward/reverse paths for flows and minimal disruption when SF
instances are added to or removed from a set. Two techniques that can
be employed are described in the following sections.
3.4.2 Modified ECMP with Consistent Hash
Symmetric forwarding into each side of an SF instance set can be
achieved with a small modification to ECMP if the packet headers are
preserved after passing through a SF instance set. In this case, each
packet's 5-tuple data can be used in a hashing function, provided the
source and destination IP address and port information are swapped in
the reverse calculation and that the same or no hash salt is used for
both directions. This method only requires that the list of available
service function instances is consistently maintained in all the load
balancers, rather than maintaining a distributed flow table.
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In the SFC architecture described in this document, when SF instances
are added or removed, the controller is required to configure (or
remove) static routes to the SF instances. The controller could
configure the load balancing function in VRFs that connect to each
added (or removed) SF instance as part of the same network
transaction as route updates to ensure that the load balancer
configuration is synchronized with the set of SF instances.
The effect of rehashing when SF instances are added or removed can be
minimized, or even eliminated using variations of the technique of
consistent hashing [consistent-hash]. Details are outside the scope
of this document.
3.4.3 ECMP with Flow Table
A second refinement that can ensure forward/reverse flow consistency,
and also provides stability when the number of SF instances changes
("flow-stickiness"), is the use of dynamically configured IP flow
tables in the VRFs. In this technique, flow tables are used to ensure
that existing flows are unaffected if the number of ECMP routes
changes, and that forward and reverse traffic passes through the same
SF instance in each set of SF instances implementing a service
function.
The flow tables are set up as follows:
1. User traffic with a new 5-tuple enters an egress VRF from a
connected SF instance.
2. The VRF calculates the ECMP hash across available routes (i.e.,
ECMP group) to the ingress interfaces of the SF instances in the
next SF instance set.
3. The VRF creates a new flow entry for the 5-tuple traffic with
the next-hop being the chosen downstream ECMP group member
(determined in the step 2. above) . All subsequent packets for the
same flow will be forwarded using flow lookup and, hence, will use
the same next-hop.
4. The encapsulated packet arrives in the routing system that
hosts the ingress VRF for the selected SF instance.
5. The ingress VRF of the next service instance determines if the
packet came from a routing system that is in an ECMP group in the
reverse direction(i.e., from this ingress VRF back to the previous
set of SF instances).
6. If an ECMP group is found, the ingress VRF creates a reverse
flow entry for the 5-tuple with next-hop of the tunnel on which
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traffic arrived.
7. The packet is sent into the SF instance connected to the
ingress VRF.
The above method ensures that forward and reverse flows pass through
the same SF instances, and that if the number of ECMP routes changes
when SF instances are added or removed, all existing flows will
continue to flow through the same SF instances, but new flows will
use the new ECMP hash. The only flows affected will be those that
were passing through an SF instance that was removed, and those will
be spread among the remaining SF instances using the updated ECMP
hash.
4 Steering into SFCs Using a Classifier
In many applications of SFCs, a classifier will be used to direct
traffic into SFCs. The classifier inspects the first or first few
packets in a flow to determine which SFC the flow should be sent
into. The decision criteria can include the IP 5-tuple of the header,
and/or analysis of the payload of packets using deep packet
inspection. Integration with a subscriber management system such as
PCRF or AAA will usually be required in order to identify which SFC
to send traffic to based on subscriber policy.
An example logical architecture is shown in Figure 9, below where a
classifier is external to a physical router.
+----------+
| PCRF/AAA |
+-----+----+
:
:
Subscriber +-----+------+
Traffic----->| Classifier |
+------------+
| |
+-------|---|------------------------+
| | | Router |
| | | |
| O O X--------->Internet
| | | / \ |
| | | O O |
+-------|---|----------------|---|---+
| | +---+ +---+ | |
| +--+ U +---+ V +-+ |
| +---+ +---+ |
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| |
| +---+ +---+ +---+ |
+--+ X +---+ Y +---+ Z +-+
+---+ +---+ +---+
Figure 9 - Subscriber/Application-Aware Steering with a Classifier
In the diagram, the classifier receives subscriber traffic and sends
the traffic out of one of two logical interfaces, depending on
classification criteria. The logical interfaces of the classifier are
connected to VRFs in a router that are entries to two SFCs (shown as
O in the diagram).
In this scenario, the exit VRF for each SFC does not peer with a
gateway or proxy node in the destination network and packets are
forwarded using IP lookup in the main routing table or in a VRF that
the exit traffic from the SFCs is directed into (shown as X in the
diagram).
An alternative would be where the classifier is itself a distributed,
virtualized service function, but with multiple egress interfaces. In
that case, each virtual classifier instance could be attached to a
set of VRFs that connect to different SFCs. Each chain entry VRF
would load balance across the first SF instance set in its SFC. The
reverse flow table mechanism described in Section 3.4.3 could be
employed to ensure that flows return to the originating classifier
instance which may maintain subscriber context and perform charging
and accounting.
5 External Domain Co-ordination
It is likely that SFCs will be managed as a separate administrative
domain from the networks that they receive traffic from, and send
traffic to. If the connected networks use BGP for route distribution,
the controller in the SFC domain can join the network domains by
creating BGP peering sessions with routing systems or route
reflectors in those network domains.
In order to steer traffic from the network domains into an SFC, the
controller will advertise a destination network's prefixes into the
peering network domain with a BGP next-hop and label associated with
the SFC entry point, that may be on a routing system attached to the
first SF instance. This advertisement may be over regular MP-BGP/VPN
peering which assumes existing standard VPN routing/forwarding
behavior on the network domain's routers (PEs/ASBRs).
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An operational benefit of this approach is also that the SFC topology
within a domain need not be exposed to other domains.
6 Fine-grained steering using BGP Flow-Spec
When steering traffic from a network domain's existing routing
systems into an SFC is desired based on attributes of the packet
flow, [FLOWSPEC] is a signaling option that can be used. In this
case, the controller advertises a flow-spec route to the network
domain's routing systems or route reflectors with the appropriate
next-hop or Service-topology-RT for the SFC entry point.
7 BGP-EVPN signaling
In a DC environment, routing systems are likely to use VXLAN based
overlays and a BGP EVPN control plane (DC-OVERLAY). For the solution
designs described earlier in the document, the BGP VPN routes for
both the SF instances and the destination networks are advertised via
BGP-EVPN, using type-2 and type-5 route types.
8 Controller Federation
When SFCs are distributed geographically, or in very large-scale
environments, there may be multiple SFC controllers present. If there
is a requirement for SFCs to span controller domains there may be a
requirement to exchange information between controllers. Again, a BGP
session between controllers can be used to exchange route information
as described in the previous sections and allow such domain spanning
SFCs to be created.
9 Summary and Conclusion
The architecture for service function chains described in this
document uses virtual networks implemented as overlays in order to
create service function chains. The virtual networks use standards-
based encapsulation tunneling, such as MPLS over GRE/UDP or VXLAN, to
transport packets into an SFC and between service function instances
without routing in the user address space. Two methods of installing
routes to form service chains are described.
In environments with physical routers, a controller may operate in
tandem with existing BGP route reflectors, and would contain the SFC
topology model, and the ability to install the local static interface
routes to SF instances. In a virtualized environment, the controller
can emulate route refection internally and simply install required
routes directly without advertisements occurring.
10 Security Considerations
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The security considerations for SFCs are broadly similar to those
concerning the data, control and management planes of any device
placed in a network. Details are out of scope for this document.
11 IANA Considerations
There are no IANA considerations.
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12 Acknowledgements
This document was prepared using 2-Word-v2.0.template.dot.
This document is a merged specification based on earlier drafts
[draft-rfernando-bess-service-chaining] and [draft-mackie-sfc-using-
virtual-networking].
The authors would like to thank D. Daino, D.R. Lopez, D. Bernier, W.
Haeffner, A. Farrel, L. Fang, and N. So, for their contributions to
the earlier drafts. The authors would also like to thank the
following individuals for their review and feedback on the original
proposals: E. Rosen, J. Guchard, P. Quinn, P. Bosch, D. Ward, A.
Ganesan, T. Morin, N. Seth, G. Pildush and N. Bitar.
13 References
13.1 Normative References
None
13.2 Informative References
[NFVE2E] "Network Functions Virtualisation: End to End Architecture,
http://docbox.etsi.org/ISG/NFV/70-DRAFT/0010/NFV-
0010v016.zip".
[RFC2328] J. Moy, "OSPF Version 2", RFC 2328, April, 1998.
[draft-merged-sfc-architecture] Halpern, J. and Pignataro, C.,
"Service Function Chaining (SFC) Architecture", draft-
ietf-sfc-architecture-09 June 2015.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, January
2007.
[RFC7348] Mahalingam, M., et al. "VXLAN: A Framework for Overlaying
Virtualized Layer 2 Networks over Layer 3 Networks.", RFC
7348, August 2014.
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[draft-ietf-l3vpn-end-system] Marques, P., et al., "BGP-signaled end-
system IP/VPNs", draft-ietf-l3vpn-end-system-04, October
2, 2014.
[FLOWSPEC] Marques, P., Sheth, N., Raszuk, R., et al.,
"Dissemination of Flow Specification Rules", RFC 5575,
August 2009.
[draft-ietf-bess-evpn-overlay-01] A. Sajassi, et al, "A Network
Virtualization Overlay Solution using EVPN", draft-ietf-
bess-evpn-overlay, February 2015.
[draft-ietf-sfc-nsh] Quinn, P., et al, "Network Service Header",
draft-ietf-sfc-nsh-00, March 2015.
[draft-niu-sfc-mechanism] Niu, L., Li, H., and Jiang, Y., "A Service
Function Chaining Header and its Mechanism", draft-niu-
sfc-mechanism-00, January 2014.
[draft-rijsman-sfc-metadata-considerations] B. Rijsman, et al.
"Metadata Considerations", draft-rijsman-sfc-metadata-
considerations-00, February 12, 2014
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. Bierman,
"Network Configuration Protocol (NETCONF)", RFC 6241, June
2011.
[RFC4023] Worster, T., Rekhter, Y., and E. Rosen, "Encapsulating MPLS
in IP or Generic Routing Encapsulation (GRE)", RFC 4023,
March 2005.
[RFC7510] Xu, X., Sheth, N. et al, "Encapsulating MPLS in UDP", RFC
7510, April 2015.
[draft-ietf-i2rs-architecture] Atlas, A., Halpern, J., Hares, S.,
Ward, D., and T Nadeau, "An Architecture for the Interface
to the Routing System", draft-ietf-i2rs-architecture, work
in progress, March 2015.
[consistent-hash] Karger, D.; Lehman, E.; Leighton, T.; Panigrahy,
R.; Levine, M.; Lewin, D. (1997). "Consistent Hashing and
Random Trees: Distributed Caching Protocols for Relieving
Hot Spots on the World Wide Web". Proceedings of the
Twenty-ninth Annual ACM Symposium on Theory of Computing.
ACM Press New York, NY, USA. pp. 654-663.
[draft-ietf-idr-link-bandwidth] P. Mohapatra, R. Fernando, "BGP Link
Bandwidth Extended Community", draft-ietf-idr-link-
Fernando-Mackie et al. Expires January 6, 2016 [Page 30]
INTERNET DRAFT Service Chaining July 5, 2015
bandwidth, work in progress.
[I-D.fang-l3vpn-virtual-pe]
L. Fang, et al., "BGP/MPLS IP VPN Virtual PE",
draft-fang-l3vpn-virtual-pe, work in progress.
[I-D.ietf-i2rs-problem-statement]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Problem Statement",
draft-ietf-i2rs-problem-statement, work in progress.
Fernando-Mackie et al. Expires January 6, 2016 [Page 31]
INTERNET DRAFT Service Chaining July 5, 2015
Authors' Addresses
Rex Fernando
Cisco
170 W Tasman Dr
San Jose, CA
Email: rex@cisco.com
Stuart Mackie
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
USA
Email: wsmackie@juniper.net
Dhananjaya Rao
Cisco
170 W Tasman Dr
San Jose, CA
Email: dhrao@cisco.com
Bruno Rijsman
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
USA
Email: brijsman@juniper.net
Maria Napierala
AT&T
200 Laurel Avenue
Middletown, NJ 07748
Email: mnapierala@att.com
Fernando-Mackie et al. Expires January 6, 2016 [Page 32]