Scaling Service Provider Scaling Service Provider Backbone using BGP Backbone using BGP Confederations for Next Confederations for Next Generation NetworksGeneration Networks

Tauqir Azam, Rishika Mehta, Ashish Tanwer

Aricent Group, Gurgaon

ContentsContents 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

AbstractAbstract 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

IntroductionIntroduction 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).

Service Provider Service Provider CharacteristicsCharacteristics

The success of a service provider depends on PerformanceReliabilityProfitabilitySecurityManageabilityConsistencyScalability

Logical Design of Service Logical Design of Service ProviderProvider

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

IGP Route PropagationIGP 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.

BGP ConfederationBGP 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.

MPLS ConfigurationMPLS 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.

Virtual Routers: VPN Virtual Routers: VPN Routing and Forwarding Routing and Forwarding (VRF)(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.

Identifying VPN routes: The Identifying VPN routes: The Route Discriminator AttributeRoute 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.

MP-BGP/MPLS VPN MP-BGP/MPLS VPN ConfigurationConfiguration

Hardware DesignHardware Design

Hardware Design Using CISCO Hardware Design Using CISCO ProductsProducts 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

Hardware Design Using JUNIPER Hardware Design Using JUNIPER ProductsProducts 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.

ConclusionConclusion 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.

ReferencesReferences[1] 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

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[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

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