BGP Multipath

BGP Multipath

by Blog

BGP Multipath

In the realm of networking, BGP (Border Gateway Protocol) plays a crucial role in determining the most efficient paths for data traffic. One fascinating aspect of BGP is the concept of multipath routing, which allows for the simultaneous use of multiple paths to reach a destination. In this blog post, we will delve into the intricacies of BGP multipath and explore its benefits, considerations, and implementation strategies.

BGP multipath refers to the capability of a BGP router to install multiple paths to the same destination in its routing table simultaneously. Unlike traditional BGP, which selects a single best path based on factors like AS path length and MED attributes, multipath considers all available paths and distributes traffic across them. This can significantly enhance network performance, reliability, and load balancing.

Load Balancing: By utilizing multiple paths, BGP multipath enables efficient distribution of traffic across diverse network links, preventing congestion and optimizing resource utilization. Redundancy and Resilience: With multiple paths, BGP multipath provides built-in redundancy, ensuring that if one path fails, traffic seamlessly switches to an alternate path, maintaining seamless connectivity.

Improved Performance: Multipath routing allows for improved performance by leveraging the available bandwidth across multiple paths, resulting in faster data transmission and reduced latency.

Convergence Time: Multipath routing may introduce longer convergence times compared to traditional BGP due to the increased complexity of path selection and decision-making processes. This should be considered when implementing multipath in time-sensitive environments.

Path Selection Criteria: It is crucial to define clear path selection criteria to ensure optimal traffic distribution. Factors like path cost, link bandwidth, and network policies should be taken into account.

Compatibility: Not all routers and network devices support BGP multipath. Therefore, compatibility checks must be performed to ensure seamless integration within the existing network infrastructure.

Configuration: Enabling BGP multipath typically involves configuring relevant parameters on BGP routers, including maximum-paths and load-sharing options.

Testing and Validation: Before deploying multipath in a production environment, thorough testing and validation should be conducted to ensure its effectiveness and compatibility with existing network components.

BGP multipath offers a compelling solution for optimizing routing efficiency, load balancing, and network resilience. By understanding its benefits and considerations, network administrators can leverage multipath routing to enhance performance, reliability, and scalability in their networks. As networks continue to evolve and demand for efficient data transmission grows, BGP multipath emerges as a valuable tool in the hands of network engineers.

Matt Conran

Highlights: BGP Multipath

Understanding BGP Multipath

BGP Multipath refers to the capability of installing multiple paths to the same destination in the routing table. Traditionally, BGP only selects a single best path based on certain criteria, such as the shortest AS path length or the lowest path cost. However, with Multipath enabled, BGP can now consider and utilize multiple paths, enhancing network performance and resiliency.

**Multipath Considerations**

a. Increased Network Resilience: One of the key advantages of BGP Multipath is the increased network resilience it offers. By utilizing multiple paths, BGP can quickly adapt and reroute traffic in case of link failures or congestion. This redundancy helps to ensure uninterrupted connectivity and reduces the impact of network disruptions.

b. Load Balancing and Traffic Engineering: Another significant benefit of BGP Multipath is load balancing. Network administrators can optimize resource utilization and prevent network congestion by distributing traffic across multiple paths. This feature is particularly useful in scenarios where multiple links to the same destination have varying capacities.

c. Path Diversity and Performance Optimization: BGP Multipath also enables path diversity, allowing networks to explore alternative routes to a destination. This flexibility can lead to improved performance by bypassing congested or suboptimal links. Additionally, Multipath facilitates better control over traffic engineering, enabling network administrators to fine-tune the data flow and optimize network performance.

**How to Configure BGP Multipath**

Configuring BGP Multipath involves a few essential steps, depending on the specific network environment and equipment being used. Here’s a general overview of the configuration process:

1. **Enable Multipath Support:** Begin by enabling BGP Multipath support on the router. This can usually be done through the router’s configuration interface, specifying the number of paths to be used.

2. **Adjust Path Selection Criteria:** Fine-tune the criteria used for selecting multiple paths to ensure they meet the network’s performance and reliability needs. This may involve setting attributes like AS path length and local preference.

3. **Monitor and Optimize:** After configuration, continuously monitor the network to ensure that BGP Multipath is performing as expected. Make adjustments as necessary to optimize performance and address any issues that arise.

Solution for BGP Multipath

BGP multipath can also be used to share loads over multiple links. A separate BGP session is configured for each link between the two routers. BGP sessions are directly associated with interface addresses. As a result, each router receives a path for each link. There is only one difference between them: the neighbor address from which the path was received. Up to the maximum-paths value configured, the router can install all paths via eBGP multipath.

The enterprise border router and the provider router must be configured with the multipath feature. The provider may not desire BGP multipath since it can cause significant memory requirements, so eBGP multi-hop may be required. This is because the command to enable this feature is not specific to a particular peer or group of peers but to all BGP prefixes on the router.

In comparison to vanilla BGP, BGP multipath offers the following advantages:

  • Multiple links can be used to load-balance traffic. 

  • Failures in BGP sessions or links have a reduced impact. 

Having multiple paths installed ensures continuous forwarding and no packet loss in case of next-hop failures. 

In the event of a failure, while multiple paths are active, the router must only remove the failed forwarding next hop rather than waiting for the RIB best path selection, FIB programming, and ASIC programming processes to complete. Only the failed path is affected, and all traffic to that destination is unaffected. 

When two multipath links are in use, traffic has an approximately half-effect. Four links affect approximately one-quarter of a system, and so on.

**The Role of BGP**

Border Gateway Protocol (BGP) was developed in 1989 to connect networks and provide interdomain routing. The goal was to create a scalable, non-chatty protocol. BGP grew in response to the overwhelming growth of the Internet, and its use cases now vary from Multicast, DDoS protection, Layer 2 services, BGP SDN, and the Routing Control Platform variations. A lot of its success comes down to the fact that it is a very well-known protocol.

**BGP Additional Features**

People know how to use BGP, and additional features are easily added, making it very extensible and easy to use. It’s much easier to troubleshoot a BGP problem than a complex IGP problem. If you want to add something new, you can create an attribute, and simple traffic engineering can be done using predefined BGP communities. Many tools are available within the protocol. Recently, there have been infrastructure improvements such as keepalive and update generation enhancements, parallel route refresh, adaptive update cache size, and multipath signaling.

Hands On – BGP Multipath

Understanding BGP Multipath

BGP Multipath allows routers to install multiple paths for the same destination in their routing tables. Traditionally, BGP selects only a single best path based on attributes like the shortest AS path length or the lowest path cost. However, Multipath enables routers to consider and utilize multiple paths concurrently, effectively distributing traffic across the available paths.

The utilization of multiple paths through BGP Multipath offers several advantages. First, it enhances network resiliency by providing redundancy. In the event of a link failure or congestion on one path, traffic can be automatically rerouted to alternative paths, ensuring uninterrupted connectivity. Additionally, BGP Multipath facilitates load balancing, allowing for efficient traffic distribution across multiple paths and optimizing network performance.

Implementing BGP Multipath involves configuration changes on the routers participating in the BGP routing process. Each router must be configured to enable Multipath and specify the maximum number of paths it can install in its routing table. Additionally, careful consideration should be given to the routing policies and attributes used for path selection to ensure optimal load balancing and redundancy.

 Knowledge Check: BGP Route Reflection

Understanding BGP Route Reflection

– BGP route reflection is a technique used to alleviate the full mesh requirement of BGP peering. In a traditional BGP setup, every router needs to establish a peering relationship with every other router in the network, resulting in a complex mesh of connections. Route reflection relaxes this requirement by introducing route reflector(s) to manage BGP updates and distribute routing information to other routers.

– Implementing BGP route reflection brings several advantages to large networks. First, it reduces required BGP peering connections, simplifying network design and configuration. This, in turn, improves scalability and lowers administrative overhead. Additionally, route reflection enhances network stability by preventing routing loops and reducing convergence time during network changes.

– To implement BGP route reflection, one or more route reflectors need to be deployed within the network. These reflectors serve as central points for receiving and distributing BGP updates. Routers within the network establish peering relationships with the reflectors, allowing them to exchange routing information. It is important to carefully design the route reflection hierarchy to ensure optimal route distribution and avoid potential bottlenecks.

BGP Add Path

Understanding the BGP Additional Paths Feature

The BGP Additional Paths feature is an extension of BGP that enables routers to advertise multiple paths for the same destination prefix. Traditionally, BGP only advertised the best route based on its selection process. However, with the Additional Paths feature, routers can now advertise and maintain additional paths, allowing for better traffic distribution and more efficient routing decisions.

Enhanced Traffic Engineering: The Additional Paths feature gives network operators more control over network traffic flow. By advertising multiple paths, operators can select paths based on various criteria, such as link utilization, latency, or specific policy requirements. This enables better traffic engineering and load balancing, improving network performance and resiliency.

Fast Convergence: With multiple paths available, the BGP Additional Paths feature allows for faster convergence during network failures or changes. When a primary path becomes unavailable, routers can quickly switch to an alternate path, minimizing the impact on network traffic and reducing downtime. This feature is particularly crucial for networks that require high availability and rapid failover capabilities.

Multi-Exit Discriminator (MED) Manipulation: The Additional Paths feature can be utilized to manipulate Multi-Exit Discriminator (MED) attributes. MED is an optional attribute BGP uses to influence the path selection process among multiple entry points into an autonomous system. By advertising different paths with varying MED values, network operators can control inbound traffic and steer it through specific entry points, optimizing network resources and improving performance.

Advanced Topic:

BGP Next Hop Tracking 

BGP’s next hop is the IP address of the next router on the path towards the destination network. It is crucial in determining the best path for routing packets across the Internet. Network administrators gain valuable insights into the network’s routing decisions by tracking the next hop.

Next-hop tracking provides numerous benefits for network operators. First, it enables proactive monitoring of the network’s routing paths, allowing administrators to identify any routing anomalies or failures quickly. Second, it aids in troubleshooting network issues by pinpointing the exact location of potential problems. Third, it assists in load-balancing traffic across multiple paths, optimizing network performance.

Implementing BGP next-hop tracking requires careful configuration and the use of specialized tools. Network devices and routers must be configured to monitor and track the next hop for each BGP route. Various network monitoring software and platforms offer features designed explicitly for BGP next-hop tracking, providing real-time visibility and alerts.

BGP next-hop tracking has applications in various networking scenarios. It is especially valuable in multi-homed networks, where redundant connections are used for enhanced reliability. Network administrators can monitor the next hop of BGP routes to ensure traffic is routed through the desired path, preventing congestion and optimizing network resources.

next hop tracking

For pre-information, you may find the following helpful

  1. Application Aware Networking
  2. Port 179

BGP Multipath

At a fundamental level, BGP multipath allows you to install multiple internal and external BGP paths to the forwarding table. Selecting multiple paths enables BGP to load-balance traffic across multiple links. This allows various BGP routes to simultaneously reach the same destination.  The principal benefits of BGP multipath compared to normal BGP are:

  • The capacity to load-balance traffic across multiple links. 
  • Decreased impact in the event of a BGP session or link failure. 

By distributing traffic across multiple paths, BGP Multipath can help alleviate congestion on certain links, prevent bottlenecks, and optimize network utilization. It can also improve resiliency and reliability by providing redundancy in case of link failures. BGP Multipath can automatically reroute traffic to the remaining available paths in a link failure, ensuring uninterrupted connectivity.

It is important to note that BGP Multipath is not enabled by default and must be explicitly configured on the routers participating in the BGP peering. Not all BGP implementations also support Multipath, so verifying compatibility with the specific router and software version is essential.

When implementing BGP Multipath, there are a few considerations to keep in mind. First, it is crucial to ensure that all links involved in the multipath configuration have comparable bandwidth, delay, and reliability characteristics. This helps prevent imbalances in traffic distribution and ensures that each path is utilized optimally.

BGP Multipath
Diagram: BGP Multipath

Second, it is essential to configure BGP Multipath to comply with the network’s policy requirements. This includes setting appropriate load balancing criteria, such as equal-cost or unequal-cost multipath, and defining the maximum number of paths allowed for a given destination prefix.

Lastly, monitoring and troubleshooting tools should be utilized to verify the correct functioning of BGP Multipath and proactively identify any issues that may arise. Regular monitoring helps ensure traffic is distributed as intended and the desired network performance goals are met.

BGP Multipath:

Best Path only & Route-Reflector clusters

BGP Multipath enables BGP to send more than just the “best” path. It is helpful in design where hot potato routing is broken. When you install a route reflector (RR), you break hot potato routing and potentially create route oscillation. Route oscillations may occur in certain network topologies combined with specific MED configurations.

A route reflector must advertise multiple paths to eliminate MED-induced route oscillations. A network with a full mesh of iBGP speakers has consistent and equivalent routing information, free from MED-induced route oscillations and other routing inconsistencies.

We need to find an approach where the RR advertises all the available paths for an address prefix or the prefixes that may cause MED-induced route oscillations. As a general design best practice to achieve consistent routing, the IGP metrics for links within a route reflector cluster are smaller than the IGP metrics for the links between the route reflector clusters.

The hot potato routing scheme

All transit providers want to protect the hot potato routing scheme for revenue reasons. Traffic consumes bandwidth and bandwidth costs money. Therefore, providers wish for traffic to leave their networks as soon as possible, aka hot potato routing. The problem is that when a route reflector receives two updates, it only sends one.

This is done by design for scalability reasons. BGP may also withdraw paths with lower policies (MED, Local Preference), resulting in only one NLRI announcement (diagram above). It was relevant, but you might want to send multiple routes for many reasons.

For example, faster convergence requires a primary and backup path and Multipath TCP use. Another issue is that the route reflector selects the best path based on its IGP and the route reflector’s shortest exit point. Route reflector deployments will choose the egress router closest to the RR, not its clients. It selects the best path based on the IGP metric computed from its IGP database and announces it to clients.

This is not optimum for egress traffic selection. As a result, traffic may travel longer paths to exit an AS. To combat this, most service providers create a full mesh of route reflectors in all regions, resulting in a route reflector in every PoP. However, an RR in every area is expensive if you have an extensive transit network.

BGP Multipath

There are several ways to get an RR or an ASBR to advertise more than one path:

  1. Different RD per prefix
  2. BGP Best External
  3. BGP Add Path
  4. BGP Optimal Route Reflection (ORR) 

The recommended method for MPLS-VPN is to assign a different RD (VPN identifier) per prefix. If you are running Layer 3 VPN, you can assign different route distinguishers (RD) to the same prefix, resulting in different IP addresses NLRI. Then, the RR sees two different prefixes and will forward both.

RR does the best path on two different VPNv4/v6 NLRI. With BGP Best External, you tell the router not to withdraw an update, even if it’s not the best one. It provides the network with an external backup route.

BGP Add path

The BGP Add path feature is a new BGP capability. It is an extension added to a BGP update where you can signal multiple paths to neighbors that must be negotiated at startup with all BGP neighbors. It’s the best method if you have a good memory and all nodes support it. All the information will be in the control plane, and you can still do hot potato routing. There are many add-path flavors, including Add-n-path, Add-all-path, and Add-all-multipath+backup.

BGP Optimal Route Reflection enables a virtual IGP location-style design. It builds multiple RIBs and computes the best path for each RIB. It would help if you influenced your IGP to mimic what it would be like in other network locations. It essentially overwrites the default IGP location placement of the route reflector, enabling clients to direct traffic to their closest exit point in hot potato routing deployments.

BGP Multipath is a powerful feature that enhances BGP-based networks’ scalability, performance, and resiliency. Enabling traffic load balancing across multiple paths helps optimize network utilization, prevent congestion, and improve overall reliability. However, careful planning, configuration, and monitoring are essential to ensure its successful implementation.

Summary: BGP Multipath

BGP multipath plays a crucial role in optimizing network performance and ensuring efficient routing. In this blog post, we explored the concept of BGP multipath, its benefits, and how it can be effectively implemented. So fasten your seatbelts and get ready to explore the fascinating world of BGP multipath!

Understanding BGP Multipath

BGP multipath, or Multipath Load Sharing (MLS), is a feature that enables multiple paths in Border Gateway Protocol (BGP) routing. Traditionally, BGP selects a single best path based on attributes such as AS path length, origin type, and MED values. However, with BGP multipath, multiple paths with equal attributes can be utilized simultaneously, leading to enhanced load balancing and improved network efficiency.

Benefits of BGP Multipath

One of the primary advantages of BGP multipath is improved network resiliency. By utilizing multiple paths, BGP multipath allows for automatic rerouting in case of link failures or congestion. This redundancy ensures uninterrupted connectivity and minimizes downtime.

Moreover, BGP multipath enables efficient resource utilization. Balancing traffic across multiple paths optimizes bandwidth utilization and prevents congestion on any single link. This results in smoother network performance, reduced latency, and improved overall user experience.

Implementation Considerations

Implementing BGP multipath requires careful planning and consideration. Network administrators must ensure that their routers and networking devices support BGP multipath functionality. Additionally, appropriate configuration and tuning are essential to maximize its benefits.

Understanding the impact of BGP multipath on routing policies is also crucial. Since BGP multipath selects multiple paths, defining policies that influence the selection process is essential. Local preference, MED values, and community attributes can affect the path selection and achieve desired routing outcomes.

Troubleshooting and Best Practices

While BGP multipath offers several advantages, it can also introduce complexity to network operations. Proper monitoring and troubleshooting mechanisms are essential to identify and resolve any issues that may arise. Regular audits and analysis of BGP multipath configurations can help maintain optimal performance.

To ensure smooth operation, best practices such as maintaining consistent path attributes across multiple paths, monitoring link utilization, and keeping routing tables up to date are recommended. Regularly reviewing and fine-tuning BGP multipath configurations can help maintain an efficient and reliable network infrastructure.

In conclusion, BGP multipath is a powerful tool that enhances network resiliency, optimizes resource utilization, and improves overall network performance. Utilizing multiple paths enables load balancing and automatic rerouting, ensuring uninterrupted connectivity. However, proper planning, configuration, and monitoring are critical to harness its benefits effectively. So, embrace the BGP multipath world and unlock your network’s full potential!

Routing Control Platform

BGP-based Routing Control Platform (RCP)

by Blog

Routing Control Platfrom

In today's fast-paced digital world, efficient network management is crucial for businesses and organizations. One technology that has revolutionized routing and network control is the Routing Control Platform (RCP). In this blog post, we will delve into the world of RCPs, exploring their features, benefits, and their potential impact on network infrastructure.

A Routing Control Platform is a software-based solution that offers centralized control and management of network routing. It acts as the brain behind the routing decisions, providing a unified platform for configuring, monitoring, and optimizing routing policies. By abstracting the underlying network infrastructure, RCPs bring simplicity and agility to network management.

Policy-based Routing: RCPs allow administrators to define routing policies based on various parameters such as network conditions, traffic patterns, and security requirements. This granular control enables efficient traffic engineering and enhances network performance.

Centralized Management: With RCPs, network administrators gain a centralized view and control of routing across multiple network devices. This simplifies configuration management, reduces complexity, and streamlines operations.

Dynamic Routing Adaptability: RCPs enable dynamic routing adaptability, which means they can automatically adjust routing decisions based on real-time network conditions. This ensures optimal traffic routing and improves network resiliency.

Enhanced Network Performance: RCPs optimize routing decisions, leading to improved network performance, reduced latency, and increased throughput. This translates into better user experiences and improved productivity.

Increased Flexibility: With RCPs, network administrators can easily adapt routing policies to changing business needs. This flexibility allows for rapid deployment of new services, efficient traffic engineering, and seamless integration with emerging technologies.

Simplified Network Management: RCPs provide a unified platform for managing and controlling routing across diverse network devices. This simplifies network management, reduces operational overhead, and enhances scalability.

Scalability: Ensure that the RCP can handle the scale of your network, supporting a large number of devices and routing policies without compromising performance.

Integration Capabilities: Look for RCPs that seamlessly integrate with your existing network infrastructure, including routers, switches, and SDN controllers. This ensures a smooth transition and minimizes disruption.

Security: Verify that the RCP offers robust security features, including authentication, access control, and encryption. Network security should be a top priority when implementing an RCP.

Routing Control Platforms have emerged as a game-changer in network management, offering centralized control, flexibility, and improved performance. By leveraging the power of RCPs, organizations can optimize their network infrastructure, adapt to changing demands, and stay ahead in the digital era.

Mattt Conran

Highlights: Routing Control Platfrom

As networks grow in complexity, managing them with traditional methods becomes increasingly challenging. Enter BGP-based routing control platforms—innovative solutions designed to streamline and optimize the routing process. These platforms leverage BGP to provide enhanced control, flexibility, and efficiency, making them indispensable tools for modern network management.

### How BGP Works

The primary function of BGP is to exchange routing information between different networks or autonomous systems (AS). Unlike other routing protocols that focus on speed, BGP prioritizes reliability and path selection based on a variety of attributes. BGP routers communicate using a process called ‘path vector protocol,’ where they share information about network paths and their associated policies. This ensures that data packets take the best possible route, avoiding congested or unreliable paths.

### The Role of Routing Control Platforms

Routing control platforms play a critical role in managing and optimizing BGP functions. These platforms offer network administrators the tools to monitor, manage, and manipulate BGP routes effectively. By using advanced analytics and automation, routing control platforms can enhance network performance, improve security, and reduce operational costs. They provide real-time insights and control, enabling swift responses to network issues or changes in traffic patterns.

Centralised Control

1: Routing control platforms are powerful tools that provide network administrators with centralized control and management over routing protocols. These platforms offer a comprehensive feature suite that allows fine-grained control over network traffic and routing decisions. From policy-based routing to traffic engineering, routing control platforms empower administrators to optimize network performance and enhance efficiency.

2: Effective routing control is vital for optimizing network performance, ensuring reliability, and improving overall internet connectivity. BGP-based routing control allows network administrators to influence the flow of traffic by manipulating route advertisements and selecting appropriate paths based on factors such as network policies, performance metrics, and economic considerations.

3: Internet Service Providers (ISPs) rely heavily on BGP-based routing control to manage the traffic within their networks and establish connections with other networks. By strategically configuring BGP policies, ISPs can control the routing of traffic to and from their networks, ensuring efficient utilization of their resources and maintaining high-quality services for their customers/

Routing control platforms come equipped with various features designed to streamline network operations. These include:

1. Policy-Based Routing: Administrators can define routing policies based on specific criteria such as source IP, destination IP, or application type. This allows for granular control over how network traffic is routed, enabling better traffic management and improved performance.

2. Traffic Engineering: Routing control platforms enable administrators to adjust network paths based on real-time traffic conditions dynamically. This ensures optimal utilization of available network resources and minimizes latency or bottlenecks.

3. Centralized Management: With a routing control platform, administrators can manage multiple routers and switches from a single, intuitive interface. This streamlines network management tasks and reduces the complexity of configuring individual devices.

Key Routing Control Benefits:

– Enhanced Scalability: RCPs enable efficient scaling of network infrastructure by allowing administrators to manage routing policies and protocols across a large number of routers from a single point of control. This eliminates the need for manual configuration on individual devices, reducing human errors and saving valuable time.

– Increased Flexibility: With RCPs, network administrators gain the ability to dynamically adapt routing policies based on network conditions and business requirements. RCPs provide a programmable interface that allows for automation and customization, empowering organizations to respond quickly to changing network demands.

– Improved Network Visibility: RCPs offer comprehensive monitoring and analytics capabilities, providing real-time insights into network performance, traffic patterns, and potential bottlenecks. This enhanced visibility enables proactive troubleshooting, efficient capacity planning, and optimization of network resource

Knowledge Check: BGP Route Reflection

Understanding BGP Route Reflection

– BGP route reflection is a technique used to alleviate the scalability issues in BGP networks with multiple routers. It allows for reducing full mesh connections, which can be resource-intensive and challenging to manage. By implementing route reflection, network administrators can maintain a hierarchical routing structure while reducing the complexity of BGP configurations.

– In a BGP route reflection setup, one or more route reflector (RR) routers are designated within a BGP autonomous system (AS). These RR routers serve as central points for route advertisement and dissemination. Instead of establishing full mesh connections between all routers in the AS, non-RR routers establish peering sessions only with the RR routers. This simplifies the BGP topology and reduces the number of required peerings.

– The implementation of BGP route reflection offers several advantages. Firstly, it reduces the number of BGP peerings required, resulting in reduced memory and CPU overhead on routers. Secondly, it improves network stability by preventing routing loops that can occur in a full mesh BGP setup. Additionally, route reflection enables better scalability, as new routers can be added to the network without significantly impacting the existing BGP infrastructure.

**Centralized Forwarding Solution**

The Routing Control Platform (RCP) is a centralized forwarding solution, similar to BGP SDN that enables the collection of a network topology map, running an algorithm, and selecting the preferred BGP route for each router in an Autonomous System (AS). It does this by peering both the IGP platform and iBGP to neighboring routers and communicating the preferred routes using unmodified iBGP.

It acts similarly to an enhanced route reflector and does not sit in the data path. It is a control plane device, separate from the IP forwarding plane. The RCP protocol exhibits the accuracy of a full mesh iBGP design and scalability enhancements of route reflection without sacrificing route selection correctness.

**Hot Potato Routing**

A potential issue with route reflection is that AS exit best path selection (hot potato routing) is performed by route reflectors from their IGP reference point, which in turn gets propagated to all RR clients scattered throughout the network. As a result, the best path selected may not be optimal for many RR clients as it depends on where the RR client is logically placed in the network.

You may also encounter MED-induced route oscillations. The Routing Control Platform aims to solve this problem.

Recap Technology: BGP Multipath

Understanding BGP Multipath

BGP Multipath, or Border Gateway Protocol Multipath, is a feature that allows a router to install multiple paths for the same destination prefix in its routing table. This means that instead of selecting a single best path, the router can utilize multiple paths simultaneously to distribute traffic. By doing so, BGP Multipath enhances the efficiency and resilience of network routing.

Enhanced Load Balancing: One of BGP Multipath’s primary advantages is its ability to achieve optimal load balancing across multiple paths. By distributing traffic across multiple links, the network can utilize available bandwidth more efficiently, preventing congestion and ensuring a smooth user experience.

Increased Fault Tolerance: In addition to load balancing, BGP Multipath improves network resilience by providing redundancy. If one path fails or experiences degradation, the router can automatically divert traffic to alternative paths, ensuring uninterrupted connectivity. This fault tolerance greatly enhances network reliability.

Routers need to be correctly configured to enable BGP Multipath. This involves helping the multipath feature, specifying the maximum number of parallel paths, and adjusting various parameters, such as the tie-breaking criteria. Network administrators must carefully plan and configure BGP Multipath to ensure optimal performance and avoid potential issues.

Advanced Topics: 

BGP Next Hop Tracking

BGP Next Hop is the IP address BGP routers use to reach a specific destination network. It is an essential component in the BGP routing table and is vital in determining the best path for data packets. However, traditional BGP routing can face challenges when link failures occur, resulting in suboptimal routing decisions. This is where BGP Next Hop Tracking comes into play.

BGP Next Hop Tracking is a feature that allows BGP routers to actively monitor the reachability of next-hop IP addresses. By tracking the next hop, routers can quickly identify whether a particular path is still valid or if an alternative route needs to be chosen. This dynamic approach enhances network resilience and reduces downtime, enabling routers to react swiftly to link failures.

a. Improved Network Resilience: BGP Next Hop Tracking ensures routing decisions are based on real-time reachability information. This capability significantly improves network resilience by dynamically adapting to changing network conditions, such as link failures or congestion.

b. Load Balancing and Traffic Engineering: With BGP Next Hop Tracking, network administrators can implement intelligent traffic engineering techniques. Routers can distribute traffic across diverse paths by actively monitoring the reachability of multiple next-hop IP addresses, balancing the load, and optimizing network performance.

c. Seamless Failover and Fast Convergence: In the event of a link failure, BGP Next Hop Tracking enables routers to switch to an alternative path swiftly with minimal disruption. This feature ensures seamless failover and fast convergence, reducing packet loss and improving overall network performance.

next hop tracking

Example: BGP Add Path

Understanding the BGP Add Path Feature

The BGP Add Path feature allows BGP routers to advertise multiple paths for a given destination prefix. Traditionally, BGP only advertised the best path to a destination, but with Add Path, routers can now advertise multiple paths, providing redundancy, load balancing, and more granular traffic engineering capabilities.

Redundancy and Resilience: The BGP Add Path feature advertises multiple paths and provides backup paths in case of failures, enhancing network resilience. This redundancy ensures uninterrupted connectivity and minimizes service disruptions.

Load Balancing: Add Path enables traffic load balancing across multiple paths, optimizing network utilization and improving performance. Network operators can distribute traffic based on factors such as link capacity, latency, or cost, ensuring efficient resource utilization.

Traffic Engineering: With BGP Add Path, network operators gain fine-grained control over traffic engineering. They can influence the path selection process by manipulating attributes associated with each path, such as AS path length or local preference. This flexibility empowers operators to optimize routing decisions based on their specific requirements.

Before you proceed, you may find the following blog BGP of interest:

  1. What is BGP protocol in networking
  2. Full Proxy
  3. What Does SDN Mean
  4. DNS Reflection Attack
  5. Segment Routing

Routing Control Platfrom

Routing Foundations

A network carries traffic where traffic flows from a start node to an end node; generally, we refer to the start node as the source node and the end node as the destination node. We must pick a path or route from the source node to the destination node. A route can be set up manually; such a route is static. Or we can have a dynamic routing protocol, such as an IGP or EGP.

With dynamic routing protocols, we have to use a routing algorithm. The role of the routing algorithm is to determine a route. Each routing algorithm will have different ways of choosing a path. Finally, a network can be expressed as a graph by mapping each node to a unique vertex in the graph, where links between network nodes are represented by edges connecting the corresponding vertices. Each edge can carry one or more weights; such weights may depict cost, delay, bandwidth, and so on. Many of these methods are now enhanced with an IGP platform and different types of routing control.

A key point: Replacing iBGP with the OpenFlow protocol

The Routing Control Platform is proposed to be enhanced by replacing iBGP with the OpenFlow protocol, which provides additional capabilities beyond next-hop forwarding. This may be useful for a BGP-free edge core and will be addressed later. The following discusses the original Routing Control Platform proposed by Princeton University and AT&T Labs-Research.

iBGP and eBGP

Routers within an AS exchange routes to external destinations using internal BGP (iBGP), and routers peer externally to their AS using external BGP (eBGP). All BGP speakers within a single AS must be fully meshed to propagate external destinations. For loop prevention, the original BGP design states reachability information learned from an iBGP router can not be forwarded to another iBGP router inside the full mesh. eBGP designs use AS-PATH for loop prevention. All routing protocols, not just BGP, require some mechanism to prevent loops.

With iBGP, the maximum number of iBGP hops an update can traverse is 1.

Example BGP Technology: Prefer eBGP over iBGP

**Section 1: Understanding eBGP and iBGP**

Before diving into the comparative advantages, it’s important to define what eBGP and iBGP are. eBGP is used for routing between different autonomous systems, making it essential for wide-area network communication, such as internet routing. Conversely, iBGP is used within the same autonomous system to ensure that all routers have a consistent view of external route information.

**Section 2: Scaling and Route Efficiency**

One of the main reasons network engineers prefer eBGP over iBGP is scalability. eBGP is designed to handle the vast scale of the internet, efficiently managing numerous routes and updates. Its ability to consolidate routing information between autonomous systems reduces the complexity seen in iBGP, which can become unwieldy as the network grows. This efficiency is particularly beneficial for internet service providers and large enterprises managing multiple connections.

**Section 3: Policy Control and Flexibility**

eBGP provides superior policy control and flexibility. It allows network administrators to apply routing policies that can manage traffic flow between autonomous systems more precisely. This level of control is crucial for optimizing network performance and ensuring that data takes the most efficient path. iBGP, while useful within an AS, lacks this external policy flexibility, making eBGP more favorable for strategic traffic routing.

**Section 4: Path Attributes and Preference**

Another consideration is the path attribute preferences in BGP. eBGP allows for the easy implementation of path attributes such as AS path, which can influence routing decisions and ensure more secure and reliable paths. This attribute is integral in avoiding routing loops and optimizing the chosen paths, offering a clear advantage over iBGP, which does not inherently prioritize these external path attributes.

BGP Configuration

 

Route-reflection (RR) and confederations

To combat the scalability concerns with an iBGP full mesh design, in 1996, several alternatives, such as route reflection and confederations, were proposed. Both of these enable hierarchies within the topology. However, route reflection has drawbacks, which may result in path diversity and network performance side effects. There is a trade-off between routing correctness and scalability. With iBGP full mesh designs, if one BGP router fails, it will have a limited impact. An update travels only one i-BGP hop. However, if a route reflector fails, it has an extensive network impact. All iBGP peers peering with the route reflector are affected. 

An update message may traverse multiple route reflectors with a route reflection design before reaching the desired i-BGP router. This may have adverse effects, such as prolonged routing convergence. One of route reflection’s most significant adverse effects is reduced path diversity. A high path diversity can increase resilience, while low path diversity will decrease resilience. Since a route reflector only passes its best route, all clients peering with that route reflector use the same path for that given destination.

Proper route reflector placement and design can eliminate some of these drawbacks. We now have path diversity mechanisms such as the BGP ADD Path capability and parallel peerings for better route reflection design. These were not available during the original RCP proposal.

Routing Control Platform (RCP)

The RCP consists of several components: 1) Route Control Server ( RCS), 2) BGP Engine, and 3) IGP platform viewer. It is similar to the newer BGP SDN platform proposed by Petr Lapukhov but has an additional IGP platform viewer function. Petr’s BGP SDN solution proposes a single Layer 3 protocol with BGP – a pure Layer 3 data center.

The RCP platform has two types of peerings: IGP and iBGP. It obtains IGP information by peering with IGP and learns BGP routes with iBGP. The Route Control Server component then analyzes the IGP and BGP viewer information to compute the best path and send it back via iBGP. Notice how the IGP Viewer only needs one peering into each partition in the diagram below.

Routing Control Platform
Diagram: Routing Control Platform

Since the link-state protocol uses reliable LSA flooding, the IGP viewer has an up-to-date topology view. To keep the IGP viewer out of the data plane, higher costs are configured on the links to the controller. As discussed, the BGP engine creates iBGP sessions for other directly reachable speakers or via the IGP.

By combining these elements, the RCS has full BGP and IGP topology information and can make routing decisions for routers in a particular partition. The RCP must have complete visibility. Otherwise, it could assign routes that create black holes, forwarding loops, or other issues preventing packets from reaching their destinations.

Centralized controller: Extract the topology

RPC uses a centralized controller to extract the topology and make routing decisions. These decisions are then pushed to the data plane nodes to forward data packets. It aims to offer the correctness of full-mesh iBGP designs and the scalability of route reflector designs. It uses iBGP sessions to peer with BGP speakers, learn topology information, and send routing decisions for destination prefixes.

As previously discussed, a route reflector design only sends its best path to clients, which limits path diversity. However, the RCP platform overcomes this route reflector limitation and sends each router a route it would have selected in an iBGP full mesh design.

Closing Points on Routing Control Platforms

Routing control platforms are the unsung heroes of network management. They are responsible for determining the best possible paths for data to travel through the internet. By analyzing various network metrics, these platforms make real-time decisions to optimize traffic flow, reduce latency, and enhance the overall user experience.

At the heart of routing control platforms lies complex algorithms and protocols. Border Gateway Protocol (BGP) is one of the key protocols that facilitate data routing between different networks. These platforms leverage BGP along with other technologies to make intelligent routing decisions. The integration of machine learning and artificial intelligence is also beginning to redefine how these platforms operate, offering predictive analytics and dynamic routing adjustments.

The evolution of routing control platforms is marked by several groundbreaking innovations. Software-Defined Networking (SDN) has emerged as a game-changer, enabling more flexible and programmable network management. Additionally, the advent of edge computing is transforming routing strategies, allowing data processing closer to the source and reducing the burden on centralized data centers.

While routing control platforms offer immense benefits, they also face significant challenges. Security remains a top concern, with platforms needing robust measures to prevent data breaches and cyber attacks. However, these challenges present opportunities for innovation, with companies investing in advanced security protocols and designing more resilient network architectures.

Summary: Routing Control Platfrom

Routing control platforms play a crucial role in managing and optimizing network infrastructures. From enhancing network performance to ensuring efficient traffic routing, these platforms have become indispensable in the digital era. In this blog post, we explored the world of routing control platforms, their functionalities, benefits, and how they empower network management.

Understanding Routing Control Platforms

Routing control platforms are sophisticated software solutions designed to control and manage network traffic routing. They provide network administrators with comprehensive visibility and control over the flow of data packets within a network. By leveraging advanced algorithms and protocols, these platforms enable efficient decision-making regarding packet routing, ensuring optimal performance and reliability.

Key Features and Functionalities

Routing control platforms offer many features and functionalities that empower network management. These include:

1. Centralized Traffic Control: Routing control platforms provide a centralized interface for monitoring and controlling network traffic. Administrators can define routing policies, prioritize traffic, and adjust routing paths based on real-time conditions.

2. Traffic Engineering: With advanced traffic engineering capabilities, these platforms enable administrators to optimize network paths and distribute traffic evenly across multiple links. This ensures efficient resource utilization and minimizes congestion.

3. Security and Policy Enforcement: Routing control platforms offer robust security mechanisms to protect networks from unauthorized access and potential threats. They enforce policies, such as access control lists and firewall rules, to safeguard sensitive data and maintain network integrity.

Benefits of Routing Control Platforms

Implementing a routing control platform brings several benefits to network management:

1. Enhanced Performance: Routing control platforms improve overall network performance by efficiently managing traffic routing and optimizing network paths, reducing latency and packet loss.

2. Increased Reliability: These platforms enable administrators to implement redundancy and failover mechanisms, ensuring uninterrupted network connectivity and minimizing downtime.

3. Flexibility and Scalability: Routing control platforms provide the flexibility to adapt to changing network requirements and scale as the network grows. They support dynamic routing protocols and can accommodate new network elements seamlessly.

Conclusion

Routing control platforms have revolutionized network management by providing administrators with powerful tools to optimize traffic routing and enhance network performance. These platforms empower organizations to build robust and efficient networks, from centralized traffic control to advanced traffic engineering capabilities. By harnessing the benefits of routing control platforms, network administrators can unlock the true potential of their infrastructures and deliver a seamless user experience.