Internet Draft
Network Working Group R. Callon
Internet Draft Juniper Networks
Expires: April 2001 B. Gleeson
Nortel Networks
Eric Rosen
Cisco Systems
Chandru Sargor
Jieyun (Jessica) Yu
Cosine Communications
Outline for A Framework for Network Based Virtual Private Networks
<draft-callon-nbvpn-outline-00.txt>
Status of this Memo
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Abstract
The work of the IETF NB-VPN working group will be aided by a working
group framework document. Input for such a document needs to come
from multiple sources, including companies involved in the major
proposals being developed by the working group.
We are intending to produce a framework document based on this
outline. The resulting document will discuss technical issues for
Network Based Virtual Private Networks (NB-VPNs). It is the intent to
produce a coherent description of the significant technical issues
which are important in the design of network based VPN solutions.
Selection of specific approaches, making choices regarding
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engineering tradeoffs, and detailed protocol specification, are
outside of the scope of a framework document.
1. Introduction
NOTE: This is a rough draft for an outline for a working group VPN
framework document. It is expected that this outline will be updated
during the process of completing the framework document. However, we
also expect that agreement will be easier if we first agree on the
general format and most of the content for the outline, and then
undertake to fill in specific sections.
The text included in this outline is intended for the purpose of
giving a general idea regarding what subjects may be discussed in
each section. It is expected that the text included herein is likely
to be re-written and/or taken from other documents. Note that in many
cases the text in this outline will consist of only brief bullet
items, which will list the general topics which are likely to be
discussed in each section.
With the exception of brief introductory material, the scope of this
outline is limited to Network Based Layer 3 VPNs. This implies VPNs
for which the provider network participates in layer 3 forwarding,
and in routing and management of the VPN, as defined below. CPE-based
VPNs are outside the scope this document. This scope is selected to
match the anticipated scope of the IETF NB-VPN working group. If the
scope of the working group is wider than anticipated, then the scope
of this outline may be extended accordingly.
This document does not make choices, but rather describes issues,
technology, and the possible solutions to each problem. We will
therefore describe multiple possible solutions which may be used.
This document does not describe any specific complete solution. Note
that any specific solution will need to make choices, and will need
to make tradeoffs between flexibility and conciseness. Also note that
the requirements for VPNs will vary between different applications,
and therefore there may be a need for multiple different solutions
for use in different situations.
1.1 Overview of Virtual Private Networks
The intention of this and the following sections is to introduce the
main characteristics of VPNs, and to specify what is in/out of scope
for this document (which is intended to match the scope of the WG).
The intention is to only briefly discuss each of the items listed
below, and refer to later sections where appropriate.
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VPNs
- private networks
- interconnected over a public infrastructure (note: To some extent
this is true of frame relay, ATM, and even ADM networks; Thus it is
not clear how "unique" this definition really is.).
- show picture. Define "provider edge (PE)" and "customer premise
edge (CPE)".
- Private addresses in the private network implies
encapsulation/tunneling (of some sort, unless there are separate
physical links)
- Need for security
- Need for QoS
- Isolation between VPNs - separate routing/forwarding tables per vpn
(at the PE gear, the input port implicitly creates restrictions
regarding where the packet can be delivered).
1.2 Types of VPNs
- Many types. It is not up to this document to decide between
different types of VPNs. There are tradeoffs.
1.2.1 CPE-Based vs Network-Based VPNs
- CPE-Based VPNs characterized by tunnels between CPE gear. Tunnels
could either be link layer connections (e.g. ATM, FR) or IP in IP (
IP/IP, GRE, IPSEC). Provider network unaware of the operation of IP
(or other network layer protocol) in the private network, just sees
ATM/FR frames or IP packets.
- Network Based VPNs - provider network participates in reachability
distribution and tunnel establishment (optionally also other
functions). Does not preclude CPE to CPE tunnels, but these are set
up with the involvement of the provider network.
- Note that these definitions actually could overlap (if the provider
manages CPE gear). A clearer distinction is whether a VPN is layer 3,
as discussed in section 1.2.4 below.
1.2.2 Types of Network Based VPNs
Different types of network based VPNs may be distinguished by the
service offered.
- Multi-site Layer 3 service - provider forwards packets based on
layer 3 information (in scope)
- Multi-site Layer 2 service - (transparent LAN service) -
provider forwards packets based on MAC address (out of scope)
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- Link Concatenation (VLL) - provider forwards packets on the
basis on the incoming link on which the packet was received (out
of scope)
1.2.3 Network Based Layer 2 VPNs
- Network is aware of VPN, but does only level 2 forwarding. Options
include forwarding based on MAC addresses, use of pt-to-pt link layer
connections, multipoint-to-pt (e.g merged MPLS LSPs), pt-to-
multipoint (e.g. ATM VCCs) etc.
1.2.4 Network Based Layer 3 VPNs
- What this is: Network layer forwarding in the carrier (specifically
in PE gear). Network is aware of the VPN (for example, it forwards L3
packets for the private network, and may participate in routing,
configuration / discovery)
- How this differs from CPE based VPNs and network based layer 2 VPNs
- Given that PE gear needs to forward packets directly from the
private network, using the private network's address space, this
implies that PE gear needs to participate in some manner in routing
for as many private networks as the PE gear supports (refer to later
sections). Basically this moves some functions from the private
network to the public network.
- "Network Connectivity Service" versus "Full Network Service".
Former provides constrained connectivity at layer 3. Latter may
include other network services such as firewalls, user authentication
and address assignment (e.g. RADIUS, DHCP) etc.
- Note: As an example, a layer 3 VPN may support constrained
connectivity, so that a single site may be in multiple VPNs, so that
to go from site 1 to site 3 you might have to traverse site 2. This
would for example make sense where the firewall is in site 2. We
don't intend to talk about how the firewall works, but will talk
about how a VPN could support constrained connectivity. Similarly
there could be NAT boxes between overlapping private address spaces
in different private networks, which would most likely provider
constraints similar to the firewalls, in that routing between two
sites may need to traverse a third site.
1.3 Terminology
1.4 Acronyms
BGP Border Gateway Protocol
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CE Customer Edge
CoS Class of Service
CPE Customer Premise Equipment CR-LDP ??
FEC Forwarding Equivalence Class
GRE Generic R?? Encapsulation
IETF Internet Engineering Task Force
IGP Interior Gateway Protocol (eg, RIP, IS-IS and OSPF
are all IGPs)
IP Internet Protocol (same as IPv4)
IPsec Internet Protocol Security protocol
IPv4 Internet Protocol version 4 (same as IP)
IPv6 Internet Protocol version 6
IS-IS Intermediate-System to Intermediate System routing
protocol
L2TP Layer 2 Tunneling Protocol
LAN Local Area Network
LDP Label Distribution Protocol
LSP Label Switched Path
MIB Management Information Base
MPLS Multi-Protocol Label Switching
NBMA Non-Broadcast Multi-Access
NMS Network Management System
OSPF Open Shortest Path First routing protocol
P Provider equipment
PE Provider-Edge equipment
PHP Penultimate-Hop Popping
PPTP Point-to-Point Tunneling Protocol
QoS Quality of Service
RFC Request for Comments
RIP Routing Information Protocol
RSVP Resource Reservation Protocol
RSVP-TE Resource Reservation Protocol with Traffic
Engineering extensions
VLAN Virtual Local Area Network
VPN Virtual Private Network
VR Virtual Router
VRF Virtual Routing and Forwarding instance
2. A Brief Overview of Requirements
Note: Generally, we expect that detailed requirements should go into
a separate document, and our understanding is that there is a
separate effort in the IETF VPN working group to define requirements.
This section will therefore be very brief.
- reference requirements document in progress
- list requirements quickly, this includes:
- ease of management (this is somewhat subjective, but is
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important)
- tunneling (to support private addressing)
- multiplexing (multiple tunnels; implicit if over IP; explicit if
over MPLS)
- security / privacy
- scaling
- in size of each VPN, number of VPNs, and in bandwidth; Number
of VPNs and Size of primary concern
- of the public network
- of each private network
- QoS support and SLA support
- intranets and extranets
Note: There is an issue regarding how much we want to say in this
section. There is a lot which could be added. However, it is probably
more appropriate to keep this very short, on the basis that the more
complete description of requirements will be in a separate document.
3. Functional Components of a VPN
Basic functional components:
1. A mechanism to discover and distribute VPN membership/capability
information
2. A mechanism to tunnel traffic among VPN sites
3. A means to exchange and maintain the private routes pertaining to
the VPN sites connected to it and reachability information for the
public backbone to be able to forward data from the VPN sites over
the backbone.
- Control plane (for setting up VPNs)
- Routing plane (for routing within a VPN)
- Data plane
Tunnels for data might or might not also be used for routing.
Note: We are not sure whether or not we will need to add a functional
decomposition internal to a PE. If this is needed to aid discussion
in the Routing or other sections to follow, then this can be added
here.
4. Customer Interface - Services and Protocols
This section to discuss the service and protocols required at the
CE/PE boundary. Includes the protocols used, and what the provider
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part of the network looks like in routing terms to the customer.
4.1 Customer view of Routing in the Private Network
- Uses normal IP routing. On a basic level, for a classic level 3
VPN, the customer does not see the VPN at all -- it looks like normal
network equipment. This implies that the customer sees a bunch of
routers, which need to be interconnected just like any old routers.
The customer expects that the quality of service and routing
capabilities of the VPN will be the same or very similar to other
network equipment. EXCEPT for the n-squared issue (see below).
- Virtual Forwarding Instances (brief introduction).
4.1.1 Options for Routing for Intranets
- Options for routing are therefore the same as is found in any
private network: One area IGP (RIP, OSPF, IS-IS, or proprietary);
Hierarchical IGP. IGP within each site, and BGP or static routing
between sites.
- Is PE router (or VFI within PE router) a part of the site? If an
IGP is used within the site, and static route between sites, is the
static route between CE and PE (probably). If BGP, maybe and maybe
not.
4.1.2 Options for Routing for Extranets
.
4.1.3 Customer Edge and Provider Edge equipment
- Above discussion is from the perspective of how routing is done on
an overall basis in a private network (eg, between sites).
- Is the PE box in a site or not?
- for one-area solution, the point is mute (everything is in the
same area)
- for multi-area or multi-domain issue, could be done either way
- If PE (or VFI) is part of site: More work for provider, less work
for private network
- If CE is border router: more control for customer.
4.1.4 Routing Across a Full N-Squared Mesh
Note: This section looks at routing from the perspective of the
customer network. If the customer has "n" sites, then from the
customer's perspective the n sites need to be interconnected and
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routing has to work between the n sites. Solutions which are specific
to PE to PE operation within an VPN solution will be discussed in
section 7.
There are a range of possible customer views of routing in the
private network. With one approach the customer only sees routing
within a single site, and a link (or a small number of links) to a
public network. With this approach there is no issue in the private
network with a view of "n-squared" links between n sites. Similarly,
in many cases the connectivity between sites may be limited. For
example, there may be a small number of core sites (one or more), and
each other site might be attached only to one or two core sites.
Finally, in many cases the number n of sites is small enough that n-
squared is still a moderate number. There are therefore a number of
cases in which there is no problem with the appearance of n-squared
links between n sites.
When n sites are fully connected between a large number of sites,
then it will look to the customer as if the topology is very richly
branched across the VPN links. How is this handled? How do you route
efficiently over the n-squared mesh?
Note that this same issue comes up in other networks. For example,
where multiple routers are interconnected over a frame relay or ATM
subnet. Standard IP routing protocols have therefore developed ways
to deal with this issue.
- discuss how this works with BGP, OSPF, and IS-IS.
- clarity PE versus CE issue (if entire topology is seen in private
network, all are routers and it doesn't matter. Else there probably
is no n-squared issue).
- Scaling may vary with routing approach -- since different private
networks have different sizes, this is one of many reasons why
multiple approaches to VPNs are needed.
4.2 Quality of Service
- QoS / SLAs
4.3 Visibility into the Provider Network
- The provider hosted part of the network may be opaque or
transparent. (May appear as a separate domain with no visibility into
internal structure, or customer may be able to log into all "virtual"
routers and modify parameters, add routes etc)
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4.4 Carrier's Carrier
We have not yet decided whether a "carrier's Carrier" service should
be included. If so, then a discussion may go here.
5. VPN Establishment and Maintenance
VPN establishment and maintenance is a very important part of any
solution for VPNs, and therefore is suggested as the first section of
the "how does the carrier actually solve the problem" discussion.
This section covers the issues and mechanisms used for the
establishment and maintenance of VPNs. There are two aspects of this
- the information distributed, and the mechanisms used to distribute
the information.
5.1 VPN Control Plane
Describe what the problem is and what we are trying to accomplish.
Finding other parts of the VPN. Applies to both intranet and extranet
case.
Information distributed may include
- Membership information (which nodes have members in which VPNs -
used to establish the control plane topology / neighbor discovery)
- Tunnel end point information (used to establish tunnels for
control and/or data) (we need to determine what this is other than
membership info)
- Topology information (full mesh / hub & spoke)
- Reachability scheme to use (e.g. per-vpn instance or shared
instance, and which protocol)
Mechanisms include
- Use BGP
- Use IGP (IS-IS or OSPF)
- Use IP multicast
- Use a VPN server / directory where nodes register and query
- Use network management system / MIB
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Discuss how the mechanisms used for the control, routing and data
planes may be combined in different ways, and how different schemes
may carry things out in a different order. e.g. 2547: combined
control and routing plane + separate data plane;
VR: separate control plane and combined routing and data plane; also
tunnels before routing for VR, tunnels after routing for 2547.
5.2 VPN Membership
Which devices need information for which VPNs? This information needs
to be dynamically distributed. Allows for neighbor discovery.
Different schemes may use this information in different ways.
Need to deal with
- Static users / sites - permanently attached to a PE via a
dedicated connection
- Dynamic users - may appear at any PE (e.g. dial users) and
attach to a VPN
Schemes may include
- advertising membership/interest in a vpn to peer nodes (e.g.
piggybacking on a routing protocol)
- registering and querying a directory or server with membership
information
5.3 Controlling VPN Route Distribution
Common problem that all schemes must address - cannot have all VPN
routes on all PEs. VPN membership information can be used to control
which devices have the routes for a particular VPN.
Mechanisms:
- route filtering (2547)
- controlling tunnel establishment (VR)
5.4 Data-Plane Topology
Each vpn has a data plane topology which consists of a set of nodes
interconnected via tunnels over which customer data traffic is sent.
This may range from a full mesh to a hub and spoke topology, or
anything in between. Different topologies may be needed for policy or
scaling reasons.
- Discuss information / mechanisms that can be used to automate
construction of the desired topology.
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Tunnels across the backbone may be either
- shared between multiple VPNs
- dedicated to a specific VPN
Discuss scaling / QoS issues regarding this.
5.5 VPN Capabilities negotiation
Advertising and selection / negotiation of common routing / tunneling
mechanisms
5.6 More detailed discussion on specific control plane mechanisms
- BGP
- LDAP
- Network Management Systems
6.0 VPN tunneling
6.1 Encapsulation
- possible formats for encapsulation, IP in IP, GRE, IPsec, MPLS
(L2TP is not in scope)
- overhead and control mechanisms may vary.
- when a packet arrives it needs to be determined which VPN it
belongs to. In many cases any one tunnel will be associated with a
single VPN. The method of making this mapping will therefore depend
upon the method of encapsulation which is used. This could use the
MPLS label, the IP address (in the case of IP in IP encapsulation),
IPsec security association, or a VPN ID. If the latter, then
somewhere in a GRE header, IPsec header, or new form of encapsulation
a place needs to be found to put a VPN ID.
- Somewhere here we need to discuss scaling, in terms of the numbers
of tunnels. We probably mention the issue here, and give more detail
below.
6.2 Tunnel Establishment
- Explicit signaling to determine multiplexing value, vs distribution
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of multiplexing value without explicit signaling (e.g. piggybacking
of MPLS label on some other protocol)
Different tunneling schemes use different methods:
- IPSec tunnels - advertise endpoint IP address and use IKE signaling
to establish the tunnel.
- MPLS LSP - advertise the MPLS label. Could also advertise endpoint
IP address and use RSVP-TE / CR-LDP to establish an LSP.
- IP/IP tunnels - no signaling, no multiplexing field - advertise
outer IP address
- GRE tunnels - no signaling, multiplexing field?
6.3 Hierarchical Tunnels
This section would discuss shared vs dedicated per-VPN tunnels and
the scaling issues involved. Some of the text below (6.4) may be
moved here. Hierarchy applies to both MPLS and non-MPLS tunnels.
Discussion of multipoint operation might also go here.
There might also be a new top level section "Hierarchical Tunnels"
(or perhaps "Tunnel Scaling") that is independent of tunnel
maintenance, since scaling and maintenance are separate issues. Use
of hierarchical tunnels appears to be primarily about scaling, but
may also have other features.
6.4 Tunnel Maintenance
- Generally, for each tunnel, we need to set it up, and over time
make sure it is still up. There may optionally be a way to remove the
tunnel in the rare chance that we are done.
- Maintenance also related to routing model used - with VR there's a
routing instance running over the tunnel so no tunnel specific
mechanisms are needed, with Aggregated this isn't the case .
- Tunnel maintenance may be explicit or implicit. For example, for IP
in IP encapsulation, if you have been told that you can encapsulate
in address "w.x.y.z" for a particular VPN, you might just send a
packet there. Similarly in some cases MPLS tunnels can be setup by
simply advertising the label to use for specific sets of traffic.
Advantages of implicit (null) maintenance: Don't need n-squared
protocol exchanges. Disadvantage: Tunnel might not work due to a
network failure. There might have been some other way around the
failure. Note that for some approaches n-squared adjacencies might
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need to exist for the routing protocol anyway (see routing section).
- Method for tunnel maintenance will vary with encapsulation.
6.4.1 Maintaining IP-in-IP and/or GRE Tunnels
We probably want to mention that tunneling over IP might be
implicitly multipoint to point. If you have "n" tunnel endpoints,
then at any one place you need only "n" pieces of information (the IP
address to tunnel to that point). If we ignore routing issues (see
section 8 below), then this implies that the scaling is O(n).
6.4.2 Maintaining LSPs as tunnels
- Label Exchange
- How do you decide which VPN is mapped to which LSP?
For this section, I think that piggybacking labels on BGP simply
makes BGP one possible signaling protocol for LSPs, although perhaps
one that in some usages becomes useful only in the specific case that
you know that you have a PE to PE tunnel, and you want to multiplex
multiple VPN-specific tunnels inside the PE to PE tunnel.
With point to point tunnels between PEs, or per-VPN between PEs, the
scaling would be O(n-squared). If a single level of tunnel is used,
each VPN-specific, and if tunnels are point to point, this could be a
lot of tunnels. This would be a problem for large networks (hundreds
of PEs). This problem can be solved through two compatible
mechanisms:
- Use hierarchical LSPs: VPN-specific tunnels can be multiplexed
inside PE-PE tunnels.
- Multipoint to point tunnels: The PE to PE tunnels can be multipoint
to point. This implies that if we have "n" PEs, then there are only
"n" LSPs within the core of the network. While each LSP could be
relatively complex (in that it has multiple branches), nonetheless on
each link there are only a maximum of n LSPs, and at each node in the
network the total amount of information is proportional to n times
the number of direct neighbors (ie, number of links * n is an upper
bound on information).
- VPN-specific tunnels which are multiplexed inside the PE to PE
tunnels can also either point to point or multipoint to point. If the
latter, then the amount of information for each ingress PE is
proportional to the number of VPNs that it supports times the number
of places that each VPN needs to send traffic. The amount of
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information for each egress PE is proportional to the number of VPNs
that it supports. This is of course a minimal amount of information
which is needed by any solution. (note, also see routing scaling,
below).
6.4.3 Maintaining IPsec Associations as Tunnels
6.5 Multiplexing
7. Routing for VPNs Across the Public Network
- This refers to carrying of Private VPN routing information across
the public network.
7.1 Virtual Forwarding Instances
- PE routers may end up supporting a large number of VPNs, and
therefore a large number of routing instances. This makes scaling
hard in PE routers. On the other hand, the resource load on a
particular PE is largely linearly proportional to the number of VPNs
that the PE router supports, and to the size of the VPNs.
- Note that with any Network Based VPN, the PE gear is involved in
routing for the private networks that it supports. This implies that
scaling of the PE gear will by definition be no better than
proportional to the number of VPNs which the PE supports times the
average size of the VPNs.
7.2 Virtual Routers
- Route across the tunnels, and treat them as normal interfaces.
- as point to point tunnels
- as an NBMA network
- as a broadcast/multicast network
- Refer to overlay routing
- Since we are routing across the tunnels, failure of the tunnels is
detected by the routing protocols.
7.3 Aggregated Routing Model
Aggregated routing means one routing instance is used to carry routes
of many or all the VPNs supported by the PEs. This implies that
routing needs to be separated from data forwarding (the tunnels are
used for data forwarding). This model routing may be piggybacked on a
common routing protocol used for multiple VPNs, possibly involving
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BGP.
The common routing protocol can be either the same protocol and
instance used for SP network routing, or a different routing
instance.
- Could use IGP or a BGP. Problems with IGP (OSPF or IS-IS implies
flooding all information throughout area). BGP allows separation of
information.
- Since we are not routing across the tunnels, other means are needed
to ensure that if the tunnels fail then either the tunnels are
rapidly re-constructed, or routing within the private network
responds.
7.3.1 Aggregated Routing with OSPF or IS-IS
- Link state protocols broadcast routing info throughout an area
- This is a problem (wrong way to distribute VPN routing
information). Scaling implications.
7.3.2 Aggregated Routing with BGP
- Flexibility regarding where information goes.
7.3.3 Managing PE to PE Backbone Networks
7.3.4 Partitioning of Routing Information with BGP
- May have separate set of route reflectors for Internet and VPN
routes
- May partition VPN routes among route reflectors
7.4 Inter-Domain Routing and Route Aggregation
This refers to dealing with VPNs which span multiple carrier routing
domains, and the routing implications thereof.
7.5 Header Lookups in the VFIs
- VFIs may (under the most straightforward implementation) have to do
more than one header lookup. Depending upon how the tunneling is
done, there could be several. Ways to reduce this are in the
following sections.
7.6 Penultimate Hop Popping for MPLS
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- How PHP reduces header lookups.
- Situations in which you can or can't use this.
7.7 Demultiplexing to Eliminate the Tunnel Egress VFI Lookup
- How this might be done
- Using MPLS
- FECs for each LSP is mapped to the next hop
- Requires more LSPs, but less forwarding lookups. this is a
straightforward engineering tradeoff of resources (which resource
would be rather use).
- This can also be done with other encapsulations. This uses more
instances / values of the 'multiplexing' field, whatever that is.
8. QoS and IP Differentiated Services
8.1 QoS in the Public Network
- VPNs may use Diff Serve, as one way to obtain the QoS which is
desired in the VPN.
- Bandwidth guarantees for LSPs
8.2 Mapping QoS from the Private to Public Network
- IP Diff Serve, as used in the VPN, may be mapped to IP Diff Serve
across the carrier network.
9. Security Issues
Note: We need to think hard about this section: This is an important
issue for VPNs. Again in a framework document we only discuss
possible solutions and their tradeoffs, we don't pick any solution.
9.1 Security of User Data
- Need for authentication and/or encryption.
- Need to protect against spoofing (sending traffic which is alleged
to come from inside the private network), and denial of service
attacks.
- CPE to CPE (is this and also host to host outside of the scope of
the working group? At least it should probably be listed as a
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possibility)
- PE to PE protection (encryption and/or authentication) does not
protect CE to PE link, but protects data between PEs.
9.2 Security of Routing Information
If overlay routing (with VRs and tunnels) then is tied to security of
the tunnels, which is the same as the security of the user data. With
aggregated model, is tied to security of a single instance of routing
information. In both cases we also depend on the security of the PEs
(assuming that if a PE is compromised then VRs within the PE will
also be compromised).
For both models, routing information is exchanged across the CE-PE
boundary. We need to consider whether this is another possible hole.
We should also discuss the impact of configuration errors. It is not
clear a priori whether this is the same or different with the
different approaches (we will need to work this out in detail).
9.3 Security of Membership Information
10. Interoperability
- It is likely that interoperability of any one VPN solution is based
on the completeness of the standard, and as such is outside of the
scope of the framework document.
- Interoperability between different VPN solutions might be discussed
here.
11. Intellectual Property
TBD.
12. Authors' Addresses
Ross Callon
Juniper Networks
1194 N. Mathilda Avenue,
Sunnyvale, CA 94089
+1-978-692-6724
E-mail: rcallon@juniper.net
Bryan Gleeson
Nortel Networks
2305 Mission College Blvd
Callon, et al. draft-callon-NBVPN-outline-00.txt [Page 17]
Internet Draft Outline for A Framework for NBVPN November, 2000
Santa Clara CA 95054
+1-408-565-2625
E-mail bgleeson@shastanets.com
Eric C. Rosen
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA, 01824
+1-978-244-8918
E-mail: erosen@cisco.com
Chandru Sargor
Cosine Communications
1200 Bridge Parkway
Redwood City, CA 94065
+1-650-637-2416
Email: Chandramouli.Sargor@cosinecom.com
Jieyun Jessica Yu
Cosine Communications
1200 Bridge Parkway
Redwood City
CA 94065
Tel: (650) 628-4881
Email: jyy@cosinecom.com
13. References
tbd.
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