In 2001, the IEEE introduced Rapid Spanning Tree Protocol (RSTP) as 802.1w. RSTP provides significantly
faster spanning tree convergence after a topology change, introducing new convergence behavior and
bridge port roles to do this. RSTP was designed to be backwards-compatible with standard STP.
While STP can take 30 to 50 seconds to respond to a topology change, RSTP is typically able to respond
to changes within 3 × Hello times (default: 3 times 2 seconds) or within a few milliseconds of a physical
link failure. The so-called Hello time is an important and configurable time interval that is used by RSTP
for several purposes; its default value is 2 seconds.
Overview of Spanning Tree Protocol (STP & RSTP)Peter R. Egli
Ethernet networks require a loop-free topology, otherwise more and more broadcastand unknown unicast frames would swamp the network (creation of frame duplicates resulting in a broadcast storm). Spanning Tree Protocol (IEEE 802.1D) and its faster successor RSTP (IEEE 802.1w) provide loop prevention in bridged networks by establising a loop-free tree of forwarding paths between any two bridges in a network with multiple physical paths. If a link fails, STP and RSTP automatically establishes a new loop-free topology. This presentation describes in detail how STP and RSTP work along with typical examples.
Spanning Tree Protocol (STP) is a network protocol designed to prevent layer 2 loops. It is standardized as IEEE 802.D protocol. STP blocks some ports on switches with redundant links to prevent broadcast storms and ensure loop-free topology. With STP in place, you can have redundant links between switches in order to provide redundancy.
It prevents a network from frame looping by putting some interfaces in forwarding state & some
interfaces in blocking state.
Whenever two or more switches are connected with each other for redundancy purpose loop can occur.
STP Protocol is used to prevent the loop. STP is layer 2 Protocol & by default it is enabled on switches.
Difference between Spanning Tree Protocol (STP) and Rapid Spanning Tree
Protocol (RSTP)
1. The main difference between Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) and Spanning
Tree Protocol (STP IEEE 802.1D) is that Rapid Spanning Tree Protocol (RSTP IEEE 802.1W)
assumes the three Spanning Tree Protocol (STP) ports states Listening, Blocking, and Disabled are
same (these states do not forward Ethernet frames and they do not learn MAC addresses).
Hence Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) places them all into a new called
Discarding state. Learning and forwarding ports remain more or less the same.
Spanning Tree Protocol (STP) is standardized as IEEE 802.1D.
Is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network.
Overview of Spanning Tree Protocol (STP & RSTP)Peter R. Egli
Ethernet networks require a loop-free topology, otherwise more and more broadcastand unknown unicast frames would swamp the network (creation of frame duplicates resulting in a broadcast storm). Spanning Tree Protocol (IEEE 802.1D) and its faster successor RSTP (IEEE 802.1w) provide loop prevention in bridged networks by establising a loop-free tree of forwarding paths between any two bridges in a network with multiple physical paths. If a link fails, STP and RSTP automatically establishes a new loop-free topology. This presentation describes in detail how STP and RSTP work along with typical examples.
Spanning Tree Protocol (STP) is a network protocol designed to prevent layer 2 loops. It is standardized as IEEE 802.D protocol. STP blocks some ports on switches with redundant links to prevent broadcast storms and ensure loop-free topology. With STP in place, you can have redundant links between switches in order to provide redundancy.
It prevents a network from frame looping by putting some interfaces in forwarding state & some
interfaces in blocking state.
Whenever two or more switches are connected with each other for redundancy purpose loop can occur.
STP Protocol is used to prevent the loop. STP is layer 2 Protocol & by default it is enabled on switches.
Difference between Spanning Tree Protocol (STP) and Rapid Spanning Tree
Protocol (RSTP)
1. The main difference between Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) and Spanning
Tree Protocol (STP IEEE 802.1D) is that Rapid Spanning Tree Protocol (RSTP IEEE 802.1W)
assumes the three Spanning Tree Protocol (STP) ports states Listening, Blocking, and Disabled are
same (these states do not forward Ethernet frames and they do not learn MAC addresses).
Hence Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) places them all into a new called
Discarding state. Learning and forwarding ports remain more or less the same.
Spanning Tree Protocol (STP) is standardized as IEEE 802.1D.
Is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network.
Mobile Transport Evolution with Unified MPLSCisco Canada
Mobile Service Providers are seeing unprecedented challenges in relation to their Transport architectures with the 3GPP evolution towards IP based Node Bs, LTE (Long Term Evolution) and LTE-Advanced. This presentation will initially discuss the network migration trends and factors that are changing how mobile networks are evolving. A description is provided on Unified MPLS and the current issues that need to be fixed and how this architecture addresses this. A more detailed analysis will then examine the options available for transporting GSM/2G, UMTS/3G traffic and IP/Ethernet Node B deployments and some of factors that need consideration like scalability, resiliency and security. Finally, there is a detailed description of the LTE/LTE - A evolution and the feature requirements made on the transport network. There will be detailed analysis of different LTE models and also some technical enhancements and proposals considered for the implementation of LTE in a Unified MPLS environment.
Spanning Tree Protocol (STP) resolves physically redundant topologies into loop-free, tree-like
topologies. The biggest issue with STP is that some hardware failures can cause it to fail. This failure
creates forwarding loops (or STP loops). Major network outages are caused by STP loops.
The loop guard STP feature that is intended to improve the stability of the Layer 2 networks. This
document also describes Bridge Protocol Data Unit (BPDU) skew detection. BPDU skew detection is a
diagnostic feature that generates syslog messages when BPDUs are not received in time.
Router Analysis, Inc. tested the Cisco ASR1004 and 1006 routers with the latest RP2, ESP40 and SIP40 hardware. The router was outfitted with Six 5 port GE SPAs and 2 10GE SPAs.
Overall the results were as expected, with the router performing within the specs provided by Cisco. For some tests the router performed at a lesser rate that expected.
Read the report to find out more.
Mobile Transport Evolution with Unified MPLSCisco Canada
Mobile Service Providers are seeing unprecedented challenges in relation to their Transport architectures with the 3GPP evolution towards IP based Node Bs, LTE (Long Term Evolution) and LTE-Advanced. This presentation will initially discuss the network migration trends and factors that are changing how mobile networks are evolving. A description is provided on Unified MPLS and the current issues that need to be fixed and how this architecture addresses this. A more detailed analysis will then examine the options available for transporting GSM/2G, UMTS/3G traffic and IP/Ethernet Node B deployments and some of factors that need consideration like scalability, resiliency and security. Finally, there is a detailed description of the LTE/LTE - A evolution and the feature requirements made on the transport network. There will be detailed analysis of different LTE models and also some technical enhancements and proposals considered for the implementation of LTE in a Unified MPLS environment.
Spanning Tree Protocol (STP) resolves physically redundant topologies into loop-free, tree-like
topologies. The biggest issue with STP is that some hardware failures can cause it to fail. This failure
creates forwarding loops (or STP loops). Major network outages are caused by STP loops.
The loop guard STP feature that is intended to improve the stability of the Layer 2 networks. This
document also describes Bridge Protocol Data Unit (BPDU) skew detection. BPDU skew detection is a
diagnostic feature that generates syslog messages when BPDUs are not received in time.
Router Analysis, Inc. tested the Cisco ASR1004 and 1006 routers with the latest RP2, ESP40 and SIP40 hardware. The router was outfitted with Six 5 port GE SPAs and 2 10GE SPAs.
Overall the results were as expected, with the router performing within the specs provided by Cisco. For some tests the router performed at a lesser rate that expected.
Read the report to find out more.
Wireless networks come in many different forms, cover various distances, and provide a range of low to
high bandwidth depending on the type installed. Wireless LAN – Wireless LAN enable Laptop users to
access the Network of a company.
Networking Devices are units that mediate data in a computer network and are also called network equipment. Units which are the last receiver or generate data are called hosts or data terminal equipment.
A network consists of a collection of computers, printers and other compatible equipment/ hardware
that is connected together so that they can communicate with each other.
For some very basic VRF configuration follow the steps:
1. Enters VRF configuration mode and assigns a VRF name.
Router(config)#ip vrf vrf-name
2. Creates a VPN route distinguisher (RD) following one of the 16bit-ASN:32bit-number or 32bitIP:16bit-number explained above
Router(config-vrf)#rd route-distinguisher
3. Creates a list of import and/or export route target communities for the specified VRF.
Router(config-vrf)# route-target {import | export | both} route-distinguisher
4. (Optional step) Associates the specified route map with the VRF.
Router(config-vrf)# import map route-map
The concept of the spanning tree protocol was devised to address broadcast storming. The spanning tree algorithm itself is defined by the IEEE standard 802.1D and its later revisions.
The IEEE Standard 802.1 uses the term bridge to define the spanning tree operation, and uses terms such as Bridge Protocol Data Units and Root Bridge when defining spanning tree protocol functions.
When a bridge receives a frame, it reads the source and destination address fields. The bridge then enters the frame’s source address in its forwarding database. In doing this the bridge associates the frame’s source address with the network attached to the por t on which the frame was received. The bridge also reads the destination address and if it can find this address in its forwarding database, it forwards the frame to the appropriate port. If the bridge does not recognize the destination address, it forwards the frame out from all its por ts except for the one on which the frame was received, and then waits for a reply. This process is known as “flooding”. Similarly, packets with broadcast or multicast destination MAC addresses will be flooded by a bridge.
A significant problem arises where bridges connect via multiple paths. A frame that arrives with an unknown or broadcast/multicast destination address is flooded over all available paths. The arrival of these frames at another network via different paths and bridges produces major problems. The bridges find the same source MAC address arriving on
multiple different por ts, making it impossible to maintain a reliable forwarding database. As a result, increasing numbers of packets will be forwarded to multiple paths. This process is selfperpetuating and produces a condition known as a packet storm, where the increase of circulating frames can eventually overload the network.
Rapid Spanning Tree Protocol enable switches to flood incoming frame with broadcast or unknown unicast destination address even in switched Ethernet networks having redundant links. It also allows switches to secretly learn location of connected devices in such networks. However some of those learnt location may become stale if a topology change is detected by RSTP and need to be flushed by switches in the network. It is find that standard address flushing technique of RSTP flushes too many addresses from large number of switches after a topology change. As a result there is a sudden massive increase in flooding traffic which may cause network-wide congestion, frame delay and frame loss. Recently a new address flushing technique named as Ring Flushing was proposed for RSTP that flushes addresses from small number of selective ports of very selective switches and so dramatically reduces the amount of flooding traffic after a topology change. However, number of flaws are identified in the current implementation of this newly proposed technique. This paper will not critically discuss the flaws in the current implementation of Ring Flushing but will also propose there simple yet effective solutions.
RRSTP: A Spanning Tree Protocol for Obviating Count-to-Infinity from Switched...CSCJournals
This paper will presents a highly reliable and rapidly converging spanning tree protocol named as Reliable Rapid Spanning Tree Protocol. The need of this spanning tree protocol is felt because reliability of switched Ethernet networks is heavily dependent upon that of spanning tree protocol. But current standard spanning tree protocol – Rapid Spanning Tree Protocol – is well known for its susceptibility to classical count-to-infinity problem. Because of this problem the protocol has extremely variable and unexpectedly high convergence time even in small networks. As a result network wide congestion, frame loss and frame delay may occur. Even forwarding loops may be induced into the network under certain circumstances. It is expected that the new protocol – RRSTP – will significantly increase the dependability of switched Ethernet networks by providing guaranteed protection against the count-to-infinity problem.
Ijcn 114DRSTP: A Simple Technique for Preventing Count-to-Infinity in RSTP Co...CSCJournals
Ethernet is a dominant local area network (LAN) technology from last three decades. Today most LANs are switched Ethernet networks. Spanning tree protocol is a vital protocol for smooth operation of switched Ethernet networks. However the current standard of spanning tree protocol for Ethernet – commonly known as Rapid Spanning Tree Protocol or in short RSTP – is highly susceptible to classical count-to-infinity problem. This problem adversely effects the network convergence time, depending upon how long count-to-infinity situation persists in the network, and thus leads to network congestion and packet loss. In the worst case, even forwarding loops may be induced that further enhances the network congestion. Thus, the dependability of RSTP controlled Ethernet networks are highly questionable due to its vulnerability against the count-to-infinity problem. This paper first discusses the count-to-infinity problem in spanning tree controlled Ethernet networks, in general and in RSTP controlled Ethernet networks, in particular. Then this paper proposes a simple solution to overwhelm this problem efficiently.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Welocme to ViralQR, your best QR code generator.ViralQR
Welcome to ViralQR, your best QR code generator available on the market!
At ViralQR, we design static and dynamic QR codes. Our mission is to make business operations easier and customer engagement more powerful through the use of QR technology. Be it a small-scale business or a huge enterprise, our easy-to-use platform provides multiple choices that can be tailored according to your company's branding and marketing strategies.
Our Vision
We are here to make the process of creating QR codes easy and smooth, thus enhancing customer interaction and making business more fluid. We very strongly believe in the ability of QR codes to change the world for businesses in their interaction with customers and are set on making that technology accessible and usable far and wide.
Our Achievements
Ever since its inception, we have successfully served many clients by offering QR codes in their marketing, service delivery, and collection of feedback across various industries. Our platform has been recognized for its ease of use and amazing features, which helped a business to make QR codes.
Our Services
At ViralQR, here is a comprehensive suite of services that caters to your very needs:
Static QR Codes: Create free static QR codes. These QR codes are able to store significant information such as URLs, vCards, plain text, emails and SMS, Wi-Fi credentials, and Bitcoin addresses.
Dynamic QR codes: These also have all the advanced features but are subscription-based. They can directly link to PDF files, images, micro-landing pages, social accounts, review forms, business pages, and applications. In addition, they can be branded with CTAs, frames, patterns, colors, and logos to enhance your branding.
Pricing and Packages
Additionally, there is a 14-day free offer to ViralQR, which is an exceptional opportunity for new users to take a feel of this platform. One can easily subscribe from there and experience the full dynamic of using QR codes. The subscription plans are not only meant for business; they are priced very flexibly so that literally every business could afford to benefit from our service.
Why choose us?
ViralQR will provide services for marketing, advertising, catering, retail, and the like. The QR codes can be posted on fliers, packaging, merchandise, and banners, as well as to substitute for cash and cards in a restaurant or coffee shop. With QR codes integrated into your business, improve customer engagement and streamline operations.
Comprehensive Analytics
Subscribers of ViralQR receive detailed analytics and tracking tools in light of having a view of the core values of QR code performance. Our analytics dashboard shows aggregate views and unique views, as well as detailed information about each impression, including time, device, browser, and estimated location by city and country.
So, thank you for choosing ViralQR; we have an offer of nothing but the best in terms of QR code services to meet business diversity!
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Quantum Computing: Current Landscape and the Future Role of APIs
RSTP (rapid spanning tree protocol)
1. RSTP (Rapid Spanning Tree Protocol)
In 2001, the IEEE introduced Rapid Spanning Tree Protocol (RSTP) as 802.1w. RSTP provides significantly
faster spanning tree convergence after a topology change, introducing new convergence behavior and
bridge port roles to do this. RSTP was designed to be backwards-compatible with standard STP.
While STP can take 30 to 50 seconds to respond to a topology change, RSTP is typically able to respond
to changes within 3 × Hello times (default: 3 times 2 seconds) or within a few milliseconds of a physical
link failure. The so-called Hello time is an important and configurable time interval that is used by RSTP
for several purposes; its default value is 2 seconds.
Standard IEEE 802.1D-2004 incorporates RSTP and obsoletes the original STP standard.
Rapid Spanning Tree Operation
RSTP adds new bridge port roles in order to speed convergence following a link failure. The number of
states a port can be in has been reduced to three instead of STP's original five.
RSTP Bridge Port Roles
1. Root Port- The port that receives the best BPDU on a bridge is the root port. This is the port that
is the closest to the root bridge in terms of path cost. The STA elects a single root bridge in the
whole bridged network (per-VLAN). The root bridge sends BPDUs that are more useful than the
ones any other bridge sends. The root bridge is the only bridge in the network that does not have
a root port. All other bridges receive BPDUs on at least one port.
2. Designated Port- A port is designated if it can send the best BPDU on the segment to which it is
connected. 802.1D bridges link together different segments, such as Ethernet segments, to
create a bridged domain. On a given segment, there can only be one path toward the root
bridge. If there are two, there is a bridging loop in the network. All bridges connected to a given
segment listen to the BPDUs of each and agree on the bridge that sends the best BPDU as the
designated bridge for the segment. The port on that bridge that corresponds is the designated
port for that segment.
Figure 1 Root Port
2. RSTP (Rapid Spanning Tree Protocol)
3. Alternate and Backup Port Roles- These two port roles correspond to the blocking state of
802.1D. A blocked port is defined as not being the designated or root port. A blocked port
receives a more useful BPDU than the one it sends out on its segment. Remember that a port
absolutely needs to receive BPDUs in order to stay blocked. RSTP introduces these two roles for
this purpose.
An alternate port receives more useful BPDUs from another bridge and is a port blocked. This is
shown in this diagram:
A backup port receives more useful BPDUs from the same bridge it is on and is a port blocked.
This is shown in this diagram:
This distinction is already made internally within 802.1D. This is essentially how Cisco UplinkFast
functions. The rationale is that an alternate port provides an alternate path to the root bridge
and therefore can replace the root port if it fails. Of course, a backup port provides redundant
Figure 2 Designated Port
Figure 3 Alternate Port
Figure 4 Backup Port
3. RSTP (Rapid Spanning Tree Protocol)
connectivity to the same segment and cannot guarantee an alternate connectivity to the root
bridge. Therefore, it is excluded from the uplink group.
New Port States
The 802.1D is defined in these five different port states:
1. Disabled
2. Listening
3. Learning
4. Blocking
5. Forwarding
STP (802.1D) Port State
RSTP (802.1w)
Port State
Is Port Included in Active
Topology?
Is Port Learning MAC Addresses?
Disabled Discarding No No
Blocking Discarding No No
Listening Discarding Yes No
Learning Learning Yes Yes
Forwarding Forwarding Yes Yes
RSTP Switch Port States
1. Discarding- No user data is sent over the port.
2. Learning- The port is not forwarding frames yet, but is populating its MAC-address-table.
3. Forwarding- The port is fully operational.
4. Detection of root switch failure is done in 3 hello times, which is 6 seconds if the default hello
times have not been changed.
5. Ports may be configured as edge ports if they are attached to a LAN that has no other bridges
attached. These edge ports transition directly to the forwarding state. RSTP still continues to
monitor the port for BPDUs in case a bridge is connected. RSTP can also be configured to
4. RSTP (Rapid Spanning Tree Protocol)
automatically detect edge ports. As soon as the bridge detects a BPDU coming to an edge port,
the port becomes a non-edge port.
6. RSTP calls the connection between two or more switches as a "link-type" connection. A port that
operates in full-duplex mode is assumed to be point-to-point link, whereas a half-duplex port
(through a hub) is considered a shared port by default. This automatic link type setting can be
overridden by explicit configuration. RSTP improves convergence on point-to-point links by
reducing the Max-Age time to 3 times Hello interval, removing the STP listening state, and
exchanging a handshake between two switches to quickly transition the port to forwarding state.
RSTP does not do anything differently from STP on shared links.
7. Unlike in STP, RSTP will respond to BPDUs sent from the direction of the root bridge. An RSTP
bridge will "propose" its spanning tree information to its designated ports. If another RSTP
bridge receives this information and determines this is the superior root information, it sets all
its other ports to discarding. The bridge may send an "agreement" to the first bridge confirming
its superior spanning tree information. The first bridge, upon receiving this agreement, knows it
can rapidly transition that port to the forwarding state bypassing the traditional
listening/learning state transition. This essentially creates a cascading effect away from the root
bridge where each designated bridge proposes to its neighbors to determine if it can make a
rapid transition. This is one of the major elements that allows RSTP to achieve faster
convergence times than STP.
8. As discussed in the port role details above, RSTP maintains backup details regarding the
discarding status of ports. This avoids timeouts if the current forwarding ports were to fail or
BPDUs were not received on the root port in a certain interval.
9. RSTP will revert to legacy STP on an interface if a legacy version of an STP BPDU is detected on
that port.
New BPDU Format
Few changes have been introduced by RSTP to the BPDU format. Only two flags, Topology Change (TC)
and TC Acknowledgment (TCA), are defined in 802.1D. However, RSTP now uses all six bits of the flag
byte that remain in order to perform:
Encode the role and state of the port that originates the BPDU
Handle the proposal/agreement mechanism
(Note: Bit 0 (Topology Change) is the least significant bit.)
5. RSTP (Rapid Spanning Tree Protocol)
Another important change is that the RSTP BPDU is now of type 2, version 2. The implication is that
legacy bridges must drop this new BPDU. This property makes it easy for a 802.1w bridge to detect
legacy bridges connected to it.
New BPDU Handling
1. BPDU are Sent Every Hello-Time.
2. Faster Aging of Information.
3. Accepts Inferior BPDUs.
RSTP Convergence Process
Its convergence Process is divided into 3 steps
1. Proposal– In this step they will exchange their BPDU.
Type 2, Version 2
2. Synchronization– In this step a switch will put its all trunk ports in discarding state. To avoid
possible loops.
3. Agreement– A switch will elect for RP and block port. After election, switch will send a request to
neighbor switch that you should be DP.
In this a switch will decide its own root port and will send a message to its neighbor switch that you
should be a designated port.
Figure 5 New BPDU Format
6. RSTP (Rapid Spanning Tree Protocol)
RSTP Port Types
Edge Port Switch to PC/Router/Server
Point-Point Switch to Switch
Shared port Switch to Hub (Ethernet Device)
(Note: RSTP (1:1) Single instance for single Vlan.)
Mixed STP and RSTP Networks
RSTP IEEE 802.1w is fully compliant with STP IEEE 802.1d. Your network can consist of bridges running
both protocols. STP and RSTP in the same network can operate together to create a single spanning tree
domain.
The switch monitors the traffic on each port for BPDU packets. When you set the switch to RSTP mode,
all the ports operate in that mode and reject STP BPDU packets. When you set the switch to operate in
STP-compatible mode, the ports can receive either RSTP or STP BPDU packets.
Rapid Spanning Tree Configuration Menu
Root Port
The active port on the switch that is communicating with the root bridge. If the switch is the root
bridge for the LAN, then there is no root port and the root port parameter will be 0.
Figure 6
7. RSTP (Rapid Spanning Tree Protocol)
Root Path Cost
The sum of all the root port costs of all the bridges between the switch’s root port and the root
bridge including the switch’s root port cost.
Time Since Topology Change
The time in seconds since the last topology change took place. When RSTP detects a change to
the LAN’s topology or when the switch is rebooted, this parameter is reset to 0 seconds and
begins incrementing until the next topology change is detected.
Topology Change Count
An integer that reflects the number of times RSTP has detected a topology change on the LAN
since the switch was initially powered on or rebooted.
The following parameters refer to the designated root bridge:
Designated Root
This parameter includes two fields: the root bridge priority and the MAC address of the root
bridge. For example, 1000 00C08F1211BB shows the root bridge priority as 1000, and
00C08F1211BB as the MAC address.
Hello Time
The hello time. See Hello Time and Bridge Protocol Data Units (BPDUs). This parameter affects
only the root bridge.
Maximum Age
The maximum amount of time that BPDUs are stored before being deleted on the root bridge.
Forward Delay
The time interval between generating and sending configuration messages by the root bridge.
The following parameters refer to the switch.
Bridge ID
The MAC address of the bridge. The bridge identifier is use as a tie breaker in the selection of the
root bridge when two or more bridges have the same bridge priority. You cannot change this
setting.
8. RSTP (Rapid Spanning Tree Protocol)
Bridge Hello Time
This is the time interval between generating and sending configuration messages by the bridge.
This parameter is active only when the switch is the root bridge.
Bridge Maximum Age
The length of time after which stored bridge protocol data units (BPDUs) are deleted by the
bridge.
Bridge Forward Delay
This is the time interval between generating and sending configuration messages by the bridge.
Topology Information Menu
Trunk- The trunk of which the port is a member.
Link- Whether the link on the port is up or down.
Desig. Root- The designated root bridge to which the switch’s root port is actively connected.
Desig. Cost- The sum of all the root port costs on all bridges, including the switch, between the
switch and the root bridge.
Desig. Bridge- An adjacent bridge to which the root port of the switch is actively connected.
Desig. Port- The root bridge to which the root port of the switch is actively connected.
RSTP Quick Summary
RSTP provides faster convergence than 802.1D STP when topology changes occur.
RSTP defines three port states: discarding, learning, and forwarding.
RSTP defines five port roles: root, designated, alternate, backup, and disabled.
9. RSTP (Rapid Spanning Tree Protocol)
Configuration Instruction
Step1: Configure SW1, SW2 and SW3 to run Rapid Per-VLAN Spanning Tree Protocol.
SW1(config)#spanning-tree mode rapid-pvst
SW1#show spanning-tree bridge
SW2(config)#spanning-tree mode rapid-pvst
SW2#show spanning-tree bridge
SW3(config)#spanning-tree mode rapid-pvst
SW3#show spanning-tree bridge
Step 2: Configure SW1 as the ROOT bridge for VLAN 1 and 10. Verify your configuration on SW2.
SW1(config)#spanning-tree vlan 1 root primary
SW1(config)#spanning-tree vlan 10 root primary
SW2#show spanning-tree vlan 1
SW2#show spanning-tree vlan 10
Step 3: Configure SW2 as the ROOT bridge for VLAN 20. Verify your configuration on SW1.
SW2(config)#spanning-tree vlan 20 root primary
SW1#show spanning-tree vlan 20
Step 4: Configure SW3 as the ROOT bridge for VLAN 30. Verify your configuration on SW1.
SW3(config)#spanning-tree vlan 30 root primary
SW1#show spanning-tree vlan 30
Figure 7