WAN Design Requirements

LISP Protocol and VM Mobility

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LISP Protocol and VM Mobility

The networking world is constantly evolving, with new technologies emerging to meet the demands of an increasingly connected world. One such technology that has gained significant attention is the LISP protocol. In this blog post, we will delve into the intricacies of the LISP protocol, exploring its purpose, benefits, and how it bridges the gap in modern networking and its use case with VM mobility.

LISP, which stands for Locator/ID Separation Protocol, is a network protocol that separates the identity of a device from its location. Unlike traditional IP addressing schemes, which rely on a tightly coupled relationship between the IP address and the device's physical location, LISP separates these two aspects, allowing for more flexibility and scalability in network design.

LISP, in simple terms, is a network protocol that separates the location of an IP address (Locator) from its identity (Identifier). By doing so, it provides enhanced flexibility, scalability, and security in managing network traffic. LISP accomplishes this by introducing two key components: the Mapping System (MS) and the Tunnel Router (TR). The MS maintains a database of mappings between Locators and Identifiers, while the TR encapsulates packets using these mappings for efficient routing.

VM mobility refers to the seamless movement of virtual machines across physical hosts or data centers. LISP Protocol plays a crucial role in enabling this mobility by decoupling the VM's IP address from its location. When a VM moves to a new host or data center, LISP dynamically updates the mappings in the MS, ensuring uninterrupted connectivity. By leveraging LISP, organizations can achieve live migration of VMs, load balancing, and disaster recovery with minimal disruption.

The combination of LISP Protocol and VM mobility brings forth a plethora of advantages. Firstly, it enhances network scalability by reducing the impact of IP address renumbering. Secondly, it enables efficient load balancing by distributing VMs across different hosts. Thirdly, it simplifies disaster recovery strategies by facilitating VM migration to remote data centers. Lastly, LISP empowers organizations with the flexibility to seamlessly scale their networks to meet growing demands.

While LISP Protocol and VM mobility offer significant benefits, there are a few challenges to consider. These include the need for proper configuration, compatibility with existing network infrastructure, and potential security concerns. However, the networking industry is consistently working towards addressing these challenges and further improving the LISP Protocol for broader adoption and seamless integration.

The combination of LISP Protocol and VM mobility opens up new horizons in network virtualization and mobility. By decoupling the IP address from its physical location, LISP enables organizations to achieve greater flexibility, scalability, and efficiency in managing network traffic. As the networking landscape continues to evolve, embracing LISP Protocol and VM mobility will undoubtedly pave the way for a more dynamic and agile networking infrastructure.

Matt Conran

Highlights: LISP Protocol and VM Mobility

Understanding LISP Protocol

– The LISP protocol, short for Locator/Identifier Separation Protocol, is a network architecture that separates the identity of a device (identifier) from its location (locator). It provides a scalable solution for routing and mobility while simplifying network design and reducing overhead. By decoupling the identifier and locator roles, LISP enables seamless communication and mobility across networks.

– Virtual machine mobility revolutionized the way we manage and deploy applications. With VM mobility, we can move virtual machines between physical hosts without interrupting services or requiring manual reconfiguration. This flexibility allows for dynamic resource allocation, load balancing, and disaster recovery. However, VM mobility also presents challenges in maintaining consistent network connectivity during migrations.

**LISP & VM Mobility**

The integration of LISP protocol and VM mobility brings forth a powerful combination. LISP provides a scalable and efficient routing infrastructure, while VM mobility enables dynamic movement of virtual machines. By leveraging LISP’s locator/identifier separation, VMs can maintain their identity while seamlessly moving across different networks or physical hosts. This synergy enhances network agility, simplifies management, and optimizes resource utilization.

The benefits of combining LISP and VM mobility are evident in various use cases. Data centers can achieve seamless workload mobility and improved load balancing. Service providers can enhance their network scalability and simplify multi-tenancy. Enterprises can optimize their network infrastructure for cloud computing and enable efficient disaster recovery strategies. The possibilities are vast, and the benefits are substantial.

How Does LISP Work

Locator Identity Separation Protocol ( LISP ) provides a set of functions that allow Endpoint identifiers ( EID ) to be mapped to an RLOC address space. The mapping between these two endpoints offers the separation of IP addresses into two numbering schemes ( similar to the “who” and the “where” analogy ), offering many traffic engineering and IP mobility benefits for the geographic dispersion of data centers beneficial for VM mobility.

LISP Components

The LISP protocol operates by creating a mapping system that separates the device’s Endpoint Identifier (EID), from its location, the Routing Locator (RLOC). This separation is achieved using a distributed database called the LISP Mapping System (LMS), which maintains the mapping between EIDs and RLOCs. When a packet is sent to a destination EID, it is encapsulated and routed based on the RLOC, allowing for efficient and scalable communication.

Before you proceed, you may find the following posts helpful:

  1. LISP Hybrid Cloud 
  2. LISP Control Plane
  3. Triangular Routing
  4. Active Active Data Center Design
  5. Application Aware Networking

 

LISP Protocol and VM Mobility

Virtualization

1- Virtualization can be applied to subsystems such as disks and a whole machine. A virtual machine (VM) is implemented by adding a software layer to an actual device to sustain the desired virtual machine’s architecture. In general, a virtual machine can circumvent real compatibility and hardware resource limitations to enable a more elevated degree of software portability and flexibility.

2- In the dynamic world of modern computing, the ability to seamlessly move virtual machines (VMs) between different physical hosts has become a critical aspect of managing resources and ensuring optimal performance. This blog post explores VM mobility and its significance in today’s rapidly evolving computing landscape.

3- VM mobility refers to transferring a virtual machine from one physical host to another without disrupting operation. Virtualization technologies such as hypervisors make this capability possible, enabling the abstraction of hardware resources and allowing multiple VMs to coexist on a single physical machine.

LISP and VM Mobility

The Locator/Identifier Separation Protocol (LISP) is an innovative networking architecture that decouples the identity (Identifier) of a device or VM from its location (Locator). By separating the two, LISP provides a scalable and flexible solution for VM mobility.

**How LISP Enhances VM Mobility**

1. Improved Scalability:

LISP introduces a level of indirection by assigning Endpoint Identifiers (EIDs) to VMs. These EIDs act as unique identifiers, allowing VMs to retain their identity even when moved to different locations. This enables enterprises to scale their VM deployments without worrying about the limitations imposed by the underlying network infrastructure.

2. Seamless VM Mobility:

LISP simplifies moving VMs by abstracting the location information using Routing Locators (RLOCs). When a VM is migrated, LISP updates the mapping between the EID and RLOC, allowing the VM to maintain uninterrupted connectivity. This eliminates the need for complex network reconfigurations, reducing downtime and improving overall agility.

3. Load Balancing and Disaster Recovery:

LISP enables efficient load balancing and disaster recovery strategies by providing the ability to distribute VMs across multiple physical hosts or data centers. With LISP, VMs can be dynamically moved to optimize resource utilization or to ensure business continuity in the event of a failure. This improves application performance and enhances the overall resilience of the IT infrastructure.

4. Interoperability and Flexibility:

LISP is designed to be interoperable with existing network infrastructure, allowing organizations to gradually adopt the protocol without disrupting their current operations. It integrates seamlessly with IPv4 and IPv6 networks, making it a future-proof solution for VM mobility.

Basic LISP Traffic flow

A device ( S1 ) initiates a connection and wants to communicate with another external device ( D1 ). D1 is located in a remote network. S1 will create a packet with the EID of S1 as the source IP address and the EID of D1 as the destination IP address. As the packets flow to the network’s edge on their way to D1, they are met by an Ingress Tunnel Router ( ITR ).

The ITR maps the destination EID to a destination RLOC and then encapsulates the original packet with an additional header with the source IP address of the ITR RLOC and the destination IP address of the RLOC of an Egress Tunnel Router ( ETR ). The ETR is located on the remote site next to the destination device D1.

LISP protocol

The magic is how these mappings are defined, especially regarding VM mobility. There is no routing convergence, and any changes to the mapping systems are unknown to the source and destination hosts. We are offering complete transparency.

LISP Terminology

LISP namespaces:

LSP Name Component

LISP Protocol Description 

End-point Identifiers  ( EID ) Addresses

The EID is allocated to an end host from an EID-prefix block. The EID associates where a host is located and identifies endpoints. The remote host obtains a destination the same way it obtains a normal destination address today, for example through DNS or SIP. The procedure a host uses to send IP packets does not change. EIDs are not routable.

Route Locator ( RLOC ) Addresses

The RLOC is an address or group of prefixes that map to an Egress Tunnel Router ( ETR ). Reachability within the RLOC space is achieved by traditional routing methods. The RLOC address must be routable.

LISP site devices:

LISP Component

LISP Protocol Description 

Ingress Tunnel Router ( ITR )

An ITR is a LISP Site device that sits in a LISP site and receives packets from internal hosts. It in turn encapsulates them to remote LISP sites. To determine where to send the packet the ITR performs an EID-to-RLOC mapping lookup. The ITR should be the first-hop or default router within a site for the source hosts.

Egress Tunnel Router ( ETR )

An ETR is a LISP Site device that receives LISP-encapsulated IP packets from the Internet, decapsulates them, and forwards them to local EIDs at the site. An ETR only accepts an IP packet where the destination address is the “outer” IP header and is one of its own configured RLOCs. The ETR should be the last hop router directly connected to the destination.

LISP infrastructure devices:

LISP Component Name

LISP Protocol Description

Map-Server ( MS )

The map server contains the EID-to-RLOC mappings and the ETRs register their EIDs to the map server. The map-server advertises these, usually as an aggregate into the LISP mapping system.

Map-Resolver ( MR )

When resolving EID-to-RLOC mappings the ITRs send LISP Map-Requests to Map-Resolvers. The Map-Resolver is typically an Anycast address. This improves the mapping lookup performance by choosing the map-resolver that is topologically closest to the requesting ITR.

Proxy ITR ( PITR )

Provides connectivity to non-LISP sites. It acts like an ITR but does so on behalf of non-LISP sites.

Proxy ETR ( PETR )

Acts like an ETR but does so on behalf of LISP sites that want to communicate to destinations at non-LISP sites.

VM Mobility

LISP Host Mobility

LISP VM Mobility ( LISP Host Mobility ) functionality allows any IP address ( End host ) to move from its subnet to either a) a completely different subnet, known as “across subnet,” or b) an extension of its subnet in a different location, known as “extended subnet,” while keeping its original IP address.

When the end host carries its own Layer 3 address to the remote site, and the prefix is the same as the remote site, it is known as an “extended subnet.” Extended subnet mode requires a Layer 2 LAN extension. On the other hand, when the end hosts carry a different network prefix to the remote site, it is known as “across subnets.” When this is the case, a Layer 2 extension is not needed between sites.

LAN extension considerations

LISP does not remove the need for a LAN extension if a VM wants to perform a “hot” migration between two dispersed sites. The LAN extension is deployed to stretch a VLAN/IP subnet between separate locations. LISP complements LAN extensions with efficient move detection methods and ingress traffic engineering.

LISP works with all LAN extensions – whether back-to-back vPC and VSS over dark fiber, VPLS, Overlay Transport Virtualization ( OTV ), or Ethernet over MPLS/IP. LAN extension best practices should still be applied to the data center edges. These include but are not limited to – End-to-end Loop Prevention and STP isolation.

A LISP site with a LAN extension extends a single site across two physical data center sites. This is because the extended subnet functionality of LISP makes two DC sites a single LISP site. On the other hand, when LISP is deployed without a LAN extension, a single LISP site is not extended between two data centers, and we end up having separate LISP sites.

LISP extended subnet

VM mobility
VM mobility: LISP protocol and extended subnets

To avoid asymmetric traffic handling, the LAN extension technology must filter Hot Standby Router Protocol ( HSRP ) HELLO messages across the two data centers. This creates an active-active HSRP setup. HSRP localization optimizes egress traffic flows. LISP optimizes ingress traffic flows.

The default gateway and virtual MAC address must remain consistent in both data centers. This is because the moved VM will continue to send to the same gateway MAC address. This is accomplished by configuring the same HSRP gateway IP address and group in both data centers. When an active-active HSRP domain is used, re-ARP is not needed during mobility events.

The LAN extension technology must have multicast enabled to support the proper operation of LISP. Once a dynamic EID is detected, the multicast group IP addresses send a map-notify message by the xTR to all other xTRs. The multicast messages are delivered leveraging the LAN extension.

LISP across subnet 

VM mobility
VM mobility: LISP protocol across Subnets

LISP across subnets requires the mobile VM to access the same gateway IP address, even if they move across subnets. This will prevent egress traffic triangulation back to the original data center. This can be achieved by manually setting the vMAC address associated with the HSRP group to be consistent across sites.

Proxy ARP must be configured under local and remote SVIs to correctly handle new ARP requests generated by the migrated workload. With this deployment, there is no need to deploy a LAN extension to stretch VLAN/IP between sites. This is why it is considered to address “cold” migration scenarios, such as Disaster Recovery ( DR ) or cloud bursting and workload mobility according to demands.

**Benefits of LISP**

1. Scalability: By separating the identifier from the location, LISP provides a scalable solution for network design. It allows for hierarchical addressing, reducing the size of the global routing table and enabling efficient routing across large networks.

2. Mobility: LISP’s separation of identity and location mainly benefits mobile devices. As devices move between networks, their EIDs remain constant while the RLOCs are updated dynamically. This enables seamless mobility without disrupting ongoing connections.

3. Multihoming: LISP allows a device to have multiple RLOCs, enabling multihoming capabilities without complex network configurations. This ensures redundancy, load balancing, and improved network reliability.

4. Security: LISP provides enhanced security features, such as cryptographic authentication and integrity checks, to ensure the integrity and authenticity of the mapping information. This helps mitigate potential attacks, such as IP spoofing.

**Applications of LISP**

1. Data Center Interconnection: LISP can interconnect geographically dispersed data centers, providing efficient and scalable communication between locations.

2. Internet of Things (IoT): With the exponential growth of IoT devices, LISP offers an efficient solution for managing these devices’ addressing and communication needs, ensuring seamless connectivity in large-scale deployments.

3. Content Delivery Networks (CDNs): LISP can optimize content delivery by allowing CDNs to cache content closer to end-users, reducing latency and improving overall performance.

Closing Points: LISP and VM Mobility

LISP is a network architecture and protocol that separates the two functions of IP addresses: identifying endpoints and routing traffic. By doing so, it allows for more efficient routing and a reduction in the complexity of network management. This separation is fundamental to enabling VM mobility, as it allows VMs to maintain consistent identities even as their physical locations change.

One of the primary benefits of LISP VM Mobility is the enhanced flexibility it provides. Businesses can move VMs across different data centers or cloud environments without having to reconfigure their network settings. This capability is particularly beneficial for disaster recovery scenarios, load balancing, and maintenance operations. Additionally, LISP VM Mobility can lead to cost savings by optimizing resource utilization and reducing the need for redundant infrastructure.

To implement LISP VM Mobility, organizations need to ensure that their network infrastructure supports the LISP protocol. This may involve updating network equipment and software to be compatible with LISP. Additionally, IT teams should be trained to manage and troubleshoot LISP-enabled environments effectively. By taking these steps, businesses can harness the full potential of LISP VM Mobility to drive innovation and efficiency.

Despite its advantages, LISP VM Mobility is not without challenges. Organizations must carefully plan the transition to ensure compatibility and minimize disruptions. Security is another critical consideration, as the dynamic nature of VM mobility can introduce new vulnerabilities. Implementing robust security measures, such as encryption and access controls, is essential to safeguarding data as it moves across networks.

 

 

Summary: LISP Protocol and VM Mobility

LISP (Locator/ID Separation Protocol) and VM (Virtual Machine) Mobility are two powerful technologies that have revolutionized the world of networking and virtualization. In this blog post, we delved into the intricacies of LISP and VM Mobility, exploring their benefits, use cases, and seamless integration.

Understanding LISP

LISP, a groundbreaking protocol, separates the role of a device’s identity (ID) from its location (Locator). By decoupling these two aspects, LISP enables efficient routing and scalable network architectures. It provides a solution to overcome the limitations of traditional IP-based routing, enabling enhanced mobility and flexibility in network design.

Unraveling VM Mobility

VM Mobility, on the other hand, refers to the ability to seamlessly move virtual machines across different physical hosts or data centers without disrupting their operations. This technology empowers businesses with the flexibility to optimize resource allocation, enhance resilience, and improve disaster recovery capabilities.

The Synergy between LISP and VM Mobility

When LISP and VM Mobility join forces, they create a powerful combination that amplifies the benefits of both technologies. By leveraging LISP’s efficient routing and location independence, VM Mobility becomes even more agile and robust. With LISP, virtual machines can be effortlessly moved between hosts or data centers, maintaining seamless connectivity and preserving the user experience.

Real-World Applications

Integrating LISP and VM Mobility opens up various possibilities across various industries. In the healthcare sector, for instance, virtual machines hosting critical patient data can be migrated between locations without compromising accessibility or security. Similarly, in cloud computing, LISP and VM Mobility enable dynamic resource allocation, load balancing, and efficient disaster recovery strategies.

Conclusion:

In conclusion, combining LISP and VM Mobility ushers a new era of network agility and virtual machine management. Decoupling identity and location through LISP empowers organizations to seamlessly move virtual machines across different hosts or data centers, enhancing flexibility, scalability, and resilience. As technology continues to evolve, LISP and VM Mobility will undoubtedly play a crucial role in shaping the future of networking and virtualization.

road sign set. Vector illustration of American and European yield traffic sign isolated on white background. Red and white triangular board with rounded corners. Flat design.

Triangular Routing

by Blog

Triangular Routing

LISP, which stands for Locator/ID Separation Protocol, is a groundbreaking networking protocol that has gained significant attention in recent years. In traditional networking, the IP address plays a dual role as both a locator and an identifier. However, LISP introduces a new approach by separating the two, allowing for more efficient and scalable routing. In this blog post, we will delve into the world of LISP and specifically explore the concept of triangular routing.

Triangular routing is a network routing technique that involves sending data packets through a triangular path instead of the traditional direct route. It aims to optimize network performance by avoiding congestion and improving redundancy. By introducing additional paths, triangular routing enhances fault tolerance and load balancing within the network.

Triangular routing is a fundamental concept within LISP that plays a crucial role in its operation. In traditional routing, packets travel from the source to the destination in a direct path. However, LISP introduces a different approach by employing a triangular routing scheme. In this scheme, packets take a detour through a mapping system known as the Mapping System (MS).

The MS acts as an intermediary, allowing the encapsulation and decapsulation of packets as they traverse the LISP-enabled network. This triangular path not only provides flexibility but also enables various LISP functionalities, such as mobility and traffic engineering.

Enhanced Network Security: By diverting traffic through an intermediate point, triangular routing provides an additional layer of security. It can help prevent direct attacks on network devices and detect potential threats more effectively.

Load Balancing: Triangular routing allows for better load distribution across different network paths. By intelligently distributing traffic, it helps prevent congestion and ensures a more balanced utilization of network resources.

Improved Network Performance: Although triangular routing may introduce additional latency due to the longer path, it can actually enhance network performance in certain scenarios. By avoiding congested or unreliable links, it helps maintain a more consistent and reliable connection.

Matt Conran

Highlights: Triangular Routing

LISP Overlay

In the ever-evolving world of networking, protocols are the unsung heroes that ensure seamless communication between devices. One such protocol that deserves attention is the Locator/ID Separation Protocol, commonly referred to as LISP. Initially developed by Cisco, LISP aims to improve the scalability and efficiency of traditional IP routing. But what sets it apart from other protocols? 

**Understanding the Basics of LISP**

Before we explore the concept of triangular routing, it’s crucial to grasp the fundamentals of LISP. At its core, LISP separates the identity of a device from its location, using a mapping system to link endpoints. This separation allows for greater flexibility, as devices can change their location without altering their identity. LISP achieves this by using two key addresses: Endpoint Identifiers (EIDs) and Routing Locators (RLOCs). The EID represents the device’s identity, while the RLOC indicates its location in the network.

**Triangular Routing: The LISP Advantage**

Triangular routing is a prominent feature of LISP, addressing a common challenge in traditional routing methods: inefficiency. In a typical network scenario, data packets travel between two endpoints through a series of hops, which may not always follow the most direct path. This can lead to increased latency and reduced performance. However, LISP introduces a novel approach by allowing packets to follow an optimized triangular path, minimizing unnecessary hops and ensuring that data takes the shortest possible route.

**How Triangular Routing Works**

In a LISP-enabled network, the triangular routing process begins with a map request from the source endpoint. This request is sent to a mapping system, which identifies the optimal path for data transmission. The mapping system then returns the best RLOC for the destination endpoint, allowing the source to send packets directly along the shortest route. This method not only enhances efficiency but also reduces bandwidth consumption, making LISP an attractive option for organizations looking to optimize their network performance.

**Real-World Applications of LISP**

The advantages of LISP and its triangular routing capabilities have made it popular among enterprises and service providers. For example, multinational companies with global data centers can leverage LISP to streamline their inter-site communications, reducing latency and improving user experience. Additionally, service providers can use LISP to offer more efficient and cost-effective services to their customers, particularly in environments where network resources are limited.

Overlay Networking with LISP

It creates an overlay network in which the core routers forward packets to RLOCs and EIDs. LISP provides a level of indirection for routing and addressing. A natural mobility feature is created as long as the EID assigned to an endpoint remains constant and the RLOCs change. LISP provides essential support for moving EIDs around, one of its many uses. All devices, whether smartphones, virtual machines, provider-to-provider roaming (physical or in the cloud), or IoT devices, are assigned EIDs with changing RLOCs.

**Original use cases**

  1. Reducing the size of the routing table in the core router
  2. Making multihoming easier to manage while preventing multiconnected sites (multihoming) from adding more routes to the core routing system
  3. Site addresses can be kept connections can be easily moved from one service provider to another and provider-independent addresses are encouraged

**Ingress Site Selection**

Supporting distributed applications is an essential requirement for business continuity. Different types of applications, be they legacy or nonlegacy, will provide particular challenges for ingress site selection. One of the main challenges designers face is workload virtualization between different geographic locations. Workload virtualization requires location independence for server resources and the ability to move these resources from one geographic area to another. This is where triangular routing comes into play.

The LISP protocol

What is triangular routing? Triangular routing is a method for transmitting packets of data in communications networks. It uses a form of routing that sends a packet to a proxy system before transmission to the intended destination. The LISP Protocol used as an Internet locator can be used as a proxy.

LISP, short for Locator/Identifier Separation Protocol, is a protocol designed to separate IP addresses’ location and identification functions. It provides a scalable and flexible solution to handle IP mobility, multi-homing, and traffic engineering. LISP achieves this by introducing two new address types: Endpoint Identifiers (EIDs) and Routing Locators (RLOCs).

Triangular routing

Implementing Triangular Routing with LISP

Now, let’s explore how LISP enables the implementation of triangular routing. By leveraging its capabilities, LISP allows for the creation of multiple paths between the source and destination. This is achieved through LISP mapping systems, which provide the necessary mapping information to enable triangular routing decisions.

Benefits of Triangular Routing with LISP

Triangular routing with LISP offers several advantages in modern network architectures. First, it enhances network resilience by providing alternate paths for data transmission. This improves fault tolerance and reduces the chances of single points of failure. Second, it allows for efficient load balancing, as traffic can be intelligently distributed across multiple paths.

Considerations and Challenges

While triangular routing with LISP brings numerous benefits, certain factors must be considered. One key consideration is the increased complexity of network configuration and management. Proper planning and expertise are required to ensure a smooth implementation. Potential issues such as suboptimal routing and increased latency should also be carefully evaluated.

Related: Before you proceed, you may find the following posts helpful for pre-information:

  1. Network Security Components
  2. LISP Hybrid Cloud
  3. Remote Browser Isolation
  4. Dynamic Workload Scaling
  5. Active Active Data Center Design
  6. Identity Security

Triangular Routing

Virtualized Workload Mobility

Virtualized Workload Mobility allows live migration between “Twin” data centers and presents several challenges. Firstly, it brings the challenge of route optimization once the workload has moved to the new location. When virtual machines are migrated between data centers, the traffic flow for client-server may become suboptimal, leading to application performance degradation.

How do existing and new connections get directed to the new location? Traditional methods, such as Route Health Injection ( RHI ) and DNS, are available but don’t suit all requirements. They can place unnecessary workloads over the data center interconnect link ( DCI ), creating a triangular routing effect discussed below.

Triangular Routing

With traditional IP routing, an IP address has two functions:

  • Identity: To identify the device.
  • Location: We use the device’s location in the network for routing.

LISP separates these two functions of an IP address into two separate tasks:

  • Endpoint Identifier (EID): Assigned to hosts like computers, laptops, printers, etc.
  • Routing Locators (RLOC): Assigned to routers. We use the RLOC address to reach EIDs.

Cisco created LISP. Originally, it was designed for the Internet, but nowadays, it is also used in other environments, such as data centers, IoT, WAN, and the campus (Cisco SD-Access).

IP Routing.

A router’s primary function is to move an IP packet from one network to a different network. Routers try to select the best loop-free path in a network that forwards a packet to its destination IP address. A router understands nonattached networks through static configuration or dynamic IP routing protocols. So, we have two routing protocols, static and dynamic.

google cloud routes

Dynamic IP routing protocols distribute network topology information between routers and provide updates without intervention when a topology change occurs. On the other hand, IP routing with static routes only accommodates topology changes well and can burden network engineers depending on the network size.

IP Routing example
Diagram: IP routing example. The source is Study CCNA.

A network routing technique

So, what is triangular routing? Triangular routing is a network routing technique that involves sending traffic through three or more points on the network. It is often used to increase the network’s reliability, security, or performance by reducing the load on any single point. In triangular routing, the data is sent from the source node to a middle node and then to the destination node. Depending on the network configuration, the central node may be a router, switch, or hub.

LISP is a map and encapsulation protocol. There are three essential environments in a LISP environment:

  • LISP sites: This is the EID namespace where EIDs are.
  • Non-LISP sites: This is the RLOC namespace where we find RLOCs. For example, the Internet.
  • LISP mapping service: This infrastructure takes care of EID-to-RLOC mappings.

Avoid congestion

Triangular routing is a common technique on the Internet. It is used to avoid congestion and increase reliability. When a connection is established between two nodes, the traffic is sent from the source to the middle node via a shorter route. If the connection between the central node and the destination node is interrupted, the data can be re-routed through another node. This ensures the data is delivered to the destination without interruption.

Example Troubleshooting Technology: Traceroute

### The Mechanics of Traceroute

Traceroute operates by sending packets with incrementing Time-To-Live (TTL) values. Each router that handles the packet decreases the TTL by one until it reaches zero, prompting an ICMP “Time Exceeded” message sent back to the sender. By observing these messages, traceroute maps the journey of the packet, revealing the IP addresses of each hop and the time taken for each segment.

### Why Traceroute Matters

Understanding the route data takes is essential for diagnosing network issues. Traceroute helps identify where delays or failures occur, be it a congested router or a broken link. This insight is invaluable for network administrators seeking to ensure efficient and reliable data delivery, making traceroute a staple in the toolkit for troubleshooting.

### Traceroute in Action

Let’s consider an example: You’re experiencing slow internet speeds. Running a traceroute can reveal if there’s a particular hop causing the delay. By examining the response times and the number of hops, you can pinpoint bottlenecks or misconfigurations in the network. This practical application underscores traceroute’s importance in maintaining network health.

Triangular routing is also used in private networks, such as corporate networks. It reduces the load on a single point, reduces latency, and increases the network’s security. In addition, each node in the triangular routing is configured with different routing protocols, making it difficult for intruders to penetrate the network.

Triangular routing is a reliable and secure technique for improving network performance. Routing data through multiple points on the network can avoid congestion and increase reliability. The following figure shows an example of triangular routing.

Hair-pinning & Triangular routing – Ingress and Egress traffic flows.

Triangular routing

  1. The external client queries its configured DNS server. The Global Load Balancing ( GLB ) device receives the request, which is authoritative for the queried domain. The GLB responds with the VIP_1 address of the local Load Balancer ( LLB ) in DC1. The VIP_1 represents the application in DC1.
  2. Traffic gets directed toward the active LLB in DC1.
  3. The LLB performs a source-NAT translation. Source-NAT changes the source IP address to the LLB’s internal IP address. This enables return traffic to be routed through the correct Load balancer, which is necessary to retain existing established sessions.
  4. The Virtual Machine ( VM ) receives the packet and replies with the destination address of the Local Load Balancer ( due to Source-NAT ).
  5. The LLB performs reverse translation and returns the packet to the external client.

Let’s assume that DC1 is overutilized and the network administrator wants to move the VM from DC1 to DC2. This move will be a hot move, a “live migration,” so all established sessions must remain intact. This is mainly because of the presence of stateful devices and the fact that we are not stretching the state of these stateful devices between the two data centers.

There is also a requirement for a LAN extension, such as OTV or vPC, between the two data centers. The LAN extension stretches VLANs and the layer 2 traffic between the two data centers.

triangular routing

  1. The client-server flows are still directed to VIP_1 from the global load balancers, as there have been no changes to site selection for existing connections. We are traversing the same stateful device as in the earlier example.
  2. The local load balancer performs Source-NAT and changes the source IP address to its inside address.
  3. The packet can reach the moved VM by leveraging the L2 LAN extension between both DCs.
  4. Any existing or new sessions using DC1’s VIP_1 will follow the suboptimal path through DC1 to reach DC2.

You hope there will be immediate changes to DNS and any new sessions ingress to DC2. This would follow the optimum path to the VIP_2, and egress traffic would follow the local gateway in DC2.

Triangular routing: The challenge

The main problem with this approach is that it works for only name-based connections, and previously established connections are hairpinned. The hair-pinning effect implies that there have been active connections to the VIP_1 ( old address ) and some new connections to the VIP_2 in the second data center for some time. Hair-pinning can put an additional load on the DCI and create a triangular routing effect.

The Solution? Locator Identity Separation Protocol ( LISP )

A new routing architecture called the Locator Identity Separation Protocol ( LISP ) was developed to overcome the challenges of workload mobility and triangular routing that were previously discussed. LISP overcomes the problems faced with route optimization when workloads migrate. It creates a new paradigm by splitting the device identity, an Endpoint Identifier ( EID ), and its location, known as its Routing Locator ( RLOC ), into two different numbering spaces.

This means we have a separate protocol representing where and who you are. The existing number scheme based on IP does not offer this flexibility, and both roles ( who and where ) are represented by one address.

LISP Control plane
LISP Control plane

Additional information on the LISP protocol 

RFC 6830 describes LISP as an Internet Protocol routing and addressing architecture. The LISP routing architecture addresses scalability, multihoming, inter-site traffic engineering, and mobility.

Internet addresses today combine location (how a device is connected to the network) and identity semantics into a single 32-bit or 128-bit number. In LISP, the location is separated from the identity. LISP allows you to change your location in a network (your network layer locator), but your identity remains the same (your network layer identifier).

A LISP separates the identifiers of end users from the routing locators used to reach them. The LISP routing architecture design separates device identity – endpoint identification (EID) – from its location – routing locator (RLOC). To further understand how LISP does the locator/ID separation, it is essential to first learn about the architectural components of LISP. The following are some of the functions or features that form the LISP architecture:

LISP Components
Diagram: LISP Components. Source Cisco Press.

LISP Host Mobility

LISP Host Mobility provides an automated solution that enables IP endpoints, such as Virtual Machines ( VM ), to change location while keeping their assigned IP address. As a result, the LISP detection and mapping system guarantees optimal routing between clients and the IP endpoints that moved. The critical point to note is that it’s an automated system.

Once the VM moves to the new location, there is no need to change DNS. The LISP control plane does not make any changes to DNS and does not require agents to be installed on the clients. It’s completely transparent.

LISP VM-mobility provides a transparent solution to end hosts and guarantees optimal path routing to the moving endpoints. It decouples the identity from the topology but creates two separate namespaces, RLOC and EID. 

The RLOCs remain associated with the topology and are reachable via traditional routing methods. The EID, which describes the end host, can dynamically change location and associate with different RLOCs. This allows the End-point Identifier space to be mobile without impacting the routing interconnecting the locator’s IP space.

LISP VM-Mobility solution:

    • VM migrations are automatically detected by the LISP Tunnel Router ( xTR ). This is accomplished by comparing the source in the IP header of traffic received from the hosts against a range of configured prefixes allowed to roam.
    • No changes are required to DNS or to install any agents. Transparent to end-users.
    • Once the move is detected, the mappings between EIDs and RLOCs are updated by the new xTR.
    • Updating the RLOC-to-EID mappings allows traffic to be redirected to the new locations without causing any updates or churn in the underlying routing. It is transparent to the core.

Load Balancing:

By distributing data packets across multiple paths, triangular routing helps balance the network load. This ensures that no single path becomes overwhelmed with traffic, preventing congestion and optimizing network performance. Load balancing improves network efficiency and minimizes latency, resulting in faster data transmission.

Fault Tolerance:

One critical advantage of triangular routing is its fault tolerance capabilities. In the event of a link failure or network congestion on one path, the other two paths can still carry the data packets to their destination. This redundancy ensures that the network remains operational despite adverse conditions, reducing the risk of data loss and maintaining uninterrupted connectivity.

Closing Points: Triangular Routing LISP 

The Locator/ID Separation Protocol (LISP) is a network architecture and protocol that separates the location and identity of network devices. This distinction allows for more scalable and efficient routing, particularly in large, complex networks. LISP addresses the limitations of traditional IP routing by decoupling the IP address into two distinct components: one for identifying the endpoint (the Identity) and one for determining the endpoint’s location (the Locator).

Triangular routing is a unique concept within the LISP protocol. It refers to a network routing scenario where data packets take a longer, indirect path between the source and destination. This can often occur in mobile networks or when dealing with certain types of address translation. While traditionally seen as a drawback due to increased latency, LISP’s innovative approach can leverage triangular routing to improve network flexibility and resilience. By strategically directing traffic through intermediary nodes, LISP can optimize routing paths and enhance performance.

One of the primary advantages of LISP’s approach to triangular routing is its ability to improve network efficiency and scalability. By dynamically managing routing paths, LISP can adapt to changes in network topology without the need for complex reconfigurations. This adaptability makes it easier to manage large-scale networks, accommodating rapid growth and changes in traffic patterns. Additionally, LISP’s triangular routing can provide better fault tolerance, ensuring continued service even when parts of the network are disrupted.

Implementing LISP within a network involves deploying LISP-capable routers and configuring them to support the protocol’s unique addressing and routing mechanisms. Network administrators can leverage LISP’s control plane to manage mappings between endpoint identifiers and locators, ensuring data packets are routed efficiently. As organizations increasingly migrate to cloud-based architectures and embrace IoT technologies, LISP offers a scalable solution to the challenges of modern networking.

Summary: Triangular Routing

The LISP (Locator/ID Separation Protocol) has revolutionized network architecture, providing efficient solutions for routing and scalability. One intriguing aspect of LISP is triangular routing, a crucial mechanism in optimizing traffic flow. In this blog post, we explored the intricacies of triangular routing within the LISP protocol, exploring its significance and functionality.

Understanding LISP Protocol

Before diving into triangular routing, it is essential to grasp the fundamentals of the LISP protocol. LISP is designed to separate the identifier (ID) and the locator (LOC) within IP addresses. By doing so, it enables efficient routing and mobility management. This separation allows for enhanced scalability and flexibility in handling network traffic.

Unveiling the Concept of Triangular Routing

Triangular routing is a crucial mechanism employed by LISP to optimize traffic flows. It involves the establishment of a direct tunnel between the source and destination devices, bypassing traditional routing paths. This tunnel ensures that packets take the shortest route possible, improving performance and reducing latency.

The Benefits of Triangular Routing

Triangular routing offers several advantages within the LISP protocol. First, it eliminates unnecessary detours by establishing a direct tunnel, thus reducing packet travel time. Second, it enhances network security by obscuring the devices’ location, making it challenging for potential attackers to pinpoint them. Third, it promotes load balancing by dynamically selecting the most efficient path for traffic flow.

Challenges and Considerations

While triangular routing brings notable benefits, it also presents challenges that must be addressed. One key consideration is the potential for suboptimal routing in specific scenarios. Careful planning and configuration are required to ensure that triangular routing is implemented correctly and does not interfere with network performance. Additionally, network administrators must be aware of the potential impact on troubleshooting and monitoring tools, as triangular routing may introduce complexities in these areas.

Conclusion:

Triangular routing plays a significant role within the LISP protocol, offering enhanced performance, security, and load-balancing capabilities. Establishing direct tunnels between devices enables efficient traffic flow and minimizes latency. However, it is essential to consider the challenges and potential trade-offs associated with triangular routing. With careful planning and configuration, network administrators can harness its benefits and optimize network performance within the LISP protocol.