1. Scaling Service Provider Backbone
using BGP Confederations for
Next Generation Networks
Tauqir Azam, Rishika Mehta, Ashish Tanwer
Aricent Group, Gurgaon

2. Contents
 Abstract
 Introduction
 Service Provider Characteristics
 SP internal architecture
 IGP Route Propagation
 BGP Confederation
 MPLS Configuration
 Virtual Routers: VPN Routing and Forwarding (VRF)
 Identifying VPN routes: The Route Discriminator Attribute
 SP Hardware design
 For Cisco
 For Juniper
 Conclusion
 References

3. Abstract
 Our paper outlines the details of internal architecture of
backbone network of Service Provider.
 The Service Provider provides high performance using latest
extensions on BGP and MPLS & is scalable enough to handle
large number of VPN customer sites.
 BGP Confederations, Route Targets (RTs) and Route
Discriminators (RDs) approaches have been used to optimize
the design.
 A sample CISCO and Juniper based deployment of the SP
(both routing and switching) considering the support of latest
protocols, security, power optimization and future extensibility.
Next-generation network implementation is based on Internet
technologies including Internet Protocol (IP) and multiprotocol
label switching (MPLS). --Wikipedia

4. Introduction
 Service Provider is an entity that provides a specific type of
service to its customers like Internet, Application services (like
Cloud), Network or backbone services (basically data services)
and Telecommunication services (different communication
services).
 Today, SP of every size and composition are active in the
market. Every service provider wants to increase subscribers,
services and ultimately, revenues.
 As a result, designing better service provider architecture and
optimization of service provider architecture is highly
demanding task.
 Service Provider architecture should be scalable to support
future subscribers and future technologies (Next Generation
protocols and services).

5. Service Provider Characteristics
The success of a service provider depends on
Performance
Reliability
Profitability
Security
Manageability
Consistency
Scalability

6. Logical Design of Service Provider

7. Service Provider Internal
Network Architecture
 In our framework, exterior BGP (EBGP) is used to make connection
between customer edge (CE) and provider edge (PE).
 The routers inside the service provider use interior BGP (IBGP) to
connect each other. Interior Gateway Protocol (IGP) is used for
internal route propagation.
 The configuration does not redistribute BGP into IGP because IGP
performance and convergence time suffers if large number of routes
are carried and no IGP is capable of carrying full Internet routing
table (exceeds 110,000 routes).
 To control the route distribution, Route Target (RT) attribute has
been used.
 The proposed service provider will provide different MPLS based
virtual private network (VPNs) to customer sites.
 Our service provider emulates virtual routers (VR) on physical
router at the software and hardware levels. These VRs have
independent IP routing and forwarding tables and they are isolated
from each other.
 BGP confederation enables to define private autonomous systems
with in the public autonomous system

8. IGP Route Propagation
 OSPF protocol is responsible to carry route to only for BGP next
hop.
 It provides optimal path to the next hop and converges to alternate
path so that the BGP peering is maintained.
 the framework take cares that the internet routes and not mixed by
the service provider internal routes carried by the OSPF.
 OSPF take use of its latest Traffic Engineering (TE) Extensions to
OSPF, to manage bandwidth of different types of traffic.

9. BGP Confederation
 The routing protocol IBGP requires full mesh between all BGP-
speaking routers. So a large number of connections and hence a large
number of TCP sessions are needed to establish IBGP connectivity.
 The traditional service provider design may suffer from unnecessarily
duplicated routing traffic. This problem is solved by using latest
extension of BGP, BGP confederations.
 BGP confederation enables to define private autonomous
systems with in the public autonomous system.

10. MPLS Configuration
 In our architecture, MPLS works in forwarding plane while MP-BGP is used as customer
route distribution protocol.
 To provide VPN through MPLS two MPLS labels are used.
 The Label 1 (Top label) points to the egress router assigned through Label/Tag
Distribution Protocol (LDP/TDP).
 The Label 2 identifies the outgoing interface on the egress router or a routing table
where a routing lookup is performed.
 In MPLS networking, a Label Switched Path (LSP) is a path through an MPLS network,
set up by a signalling protocol such as LDP, RSVP-TE, BGP (in the architecture).
 In our architecture, the forward equivalence call (FEC) of MPLS is equal to a VPN site
descriptor or VPN routing table.

11. Virtual Routers: VPN Routing
and Forwarding (VRF)
 To maintain security, it is necessary to constrain distribution of routing information at
PE that has sites from multiple (disjoint) VPNs attached to it.
 The solution of problem is that PE must maintain multiple Forwarding Tables, one table
per set of directly attached sites with common VPN membership e.g., one for all the
directly attached sites that are in just one particular VPN.
 Routes receives from other PEs (via BGP) restricted to only the routes of the VPN(s)
the site(s) is in via route filtering based on BGP Route Target (RT) Attribute.

12. Identifying VPN routes: The Route
Discriminator Attribute
 To maintain security, it is necessary to constrain distribution of routing information at
PE that has sites from multiple (disjoint) VPNs attached to it.
 Route distinguisher is used to uniquely identify VPN routes in the SP core.
 Route distinguisher, is a 64-bit value defined uniquely for each user group.
 To ensure VPNv4 route uniqueness, the customer IPv4 routes are prepended with a
uniquely defined RD to create a distinct VPNv4 prefix.
 Every VRF configuration requires an RD to be defined. Its uniqueness guarantees
customer VPNv4 uniqueness.

13. MP-BGP/MPLS VPN
Configuration

14. Hardware Design

15. Hardware Design Using CISCO Products
 PE routers requires high-performance IP/MPLS features as well as scalable
personalized IP services at the network edge, improve operational efficiency,
and maximize return on network investments. Cisco 7600 series routers are
ideal for the purpose.
 The Cisco 7600 Series is the carrier-class edge router to offer integrated,
high-density Ethernet switching, carrier-class IP/MPLS routing, and 10-Gbps
interfaces that enables service providers to deliver both consumer and
business services over a single converged Carrier Ethernet network.
 The processing load on CE routers is much less than that on PE routers and
our service provider uses economical Cisco 7200 series Router for the
purpose.
 For Layer 2 switching, the switch selected must provide the planned network
backbone capacity. Since the capacity of service provider depends on the
capacity of core switches. Cisco Catalyst 6500 Series Switches are ideal for
the purpose.
 Catalyst 6500 Series Switches deliver performance of 2 terabits per second
(Tbps). The switch fabric delivers 80 Gbps switching capacity per slot and
scales to 4 Tbps system capacity

16. Hardware Design Using JUNIPER Products
 PE routers requires high-performance IP/MPLS features as well as scalable personalized
IP services at the network edge, improve operational efficiency, and maximize return
on network investments. Juniper MX960 3D Universal Edge Router is ideal for the
purpose.
 The MX900 3D Universal Edge Router is a high-density Layer 2 and Layer 3 Ethernet
platform for service provider Ethernet edge scenarios. The MX960 provides a range of
Ethernet services, Including VPLS services for multi-point connectivity.
 The processing load on CE routers is much less than that on PE routers and our
service provider uses MX480 3D Universal Edge Router for the purpose. Juniper
MX960 3D Universal Edge Router is ideal for the purpose.
 The MX900 3D Universal Edge Router is a high-density Layer 2 and Layer 3 Ethernet
platform for service provider Ethernet edge scenarios.
 Switch that can efficiently scale performance and network services, virtualize, secure,
and manage network remotely. Juniper EX 8200 Series Switches are ideal for the
purpose.
 The EX82xx line of modular Ethernet switches is a family of high-performance, highly
available platforms for use in high-density 10GbE (10-Gbps) data centers, campus
aggregations and core networks.

17. Conclusion
 Our paper outlines the internal architecture, network configuration
and hardware design of backbone network of high performance SP.
 The SP design configuration implements the latest extensions on
BGP and MPLS and is scalable enough to handle large number of
VPN customer sites.
 Route Reflectors (RRs) have been replaced by BGP Confederations.
 Route Targets (RTs) and Route Discriminators (RDs) approaches
have been used to Control Route Distribution and to Identify VPN
routes. SP H/W requirements and corresponding design
 The service provider design configuration implements the latest
extensions on BGP and MPLS and is scalable enough to handle large
number of VPN customer
 Sample CISCO and Juniper based deployment of the service
provider (both routing and switching) has been proposed
considering the support of latest protocols, security, power
optimization and future extensibility.
 The presented generic SP design can be easily modified to provide
typically any services that need high performance Next Generation
backbone network.

18. [1]
References
Susan Hares et al., “A Border Gateway Protocol 4 (BGP-4)”, n.d., http://tools.ietf.org/html/rfc4271
[2] Y. Rekhter and P. Gross, “Application of the Border Gateway Protocol in the Internet”, n.d.,
http://tools.ietf.org/html/rfc1772
[3] Curtis Villamizar, Ramesh Govindan, and Ravi Chandra, “BGP Route Flap Damping”, n.d.,
http://tools.ietf.org/html/rfc2439
[4] Tony Bates, Enke Chen, and Ravi Chandra, “BGP Route Reflection: An Alternative to Full Mesh Internal BGP
(IBGP)”, n.d., http://tools.ietf.org/html/rfc4456
[5] Enke Chen and Quaizar Vohra, “BGP Support for Four-octet AS Number Space”, n.d.,
http://tools.ietf.org/html/rfc4893
[6] Yakov Rekhter and Eric C Rosen, “BGP/MPLS VPNs”, n.d., http://tools.ietf.org/html/rfc2547
[7] Dave Katz et al., “Multiprotocol Extensions for BGP-4”, n.d., http://tools.ietf.org/html/rfc4760
[8] Enke Chen <enkechen@siara.com>, “Route Refresh Capability for BGP-4”, n.d.,
http://tools.ietf.org/html/rfc2918
[9] Yakov Rekhter and Eric C Rosen, “BGP/MPLS IP Virtual Private Networks (VPNs)”, n.d.,
http://tools.ietf.org/html/rfc4364
[10] Yakov Rekhter <yakov@juniper.net>, “Carrying Label Information in BGP-4”, n.d.,
http://tools.ietf.org/html/rfc3107
[11] Lou Berger et al., “Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point-to-
Multipoint TE Label Switched Paths (LSPs)”, n.d., http://tools.ietf.org/html/rfc4875
[12] Yakov Rekhter and Rahul Aggarwal, “Graceful Restart Mechanism for BGP with MPLS”, n.d.,
http://tools.ietf.org/html/rfc4781
[13] Eric Gray <egray@zaffire.com>, “LDP Applicability”, n.d., http://tools.ietf.org/html/rfc3037
[14] Daniel O Awduche et al., “RSVP-TE: Extensions to RSVP for LSP Tunnels”, n.d.,
http://tools.ietf.org/html/rfc3209 ; Kireeti Kompella
[15] Dave Katz, and Derek M Yeung, “Traffic Engineering (TE) Extensions to OSPF Version 2”, n.d.,
http://tools.ietf.org/html/rfc3630
[16] J. Moy, “OSPF Version 2”, n.d., http://tools.ietf.org/html/rfc2328
[17] R. Hinden, Ed., “Virtual Router Redundancy Protocol (VRRP)”, nd, http://tools.ietf.org/rfc/rfc3768

19. QUESTIONS