Common Networking Protocols in LAN, WAN and Datacenter

Spanning Tree, Link Aggregation , VLAN and First Hop Redundancy protocols are used in Campus, Service Provider Access and Aggregation and in the Datacenter environment. There are definitely other protocols which are common across the Places in the Networks but in order to keep this article short and meaningful I choose these four.

I will describe Spanning tree, link aggregation, 802.1q Vlan and First hop redundancy protocols at a high level since I will explained them in detail later in the separate articles.

For the more advanced layer 2 protocol information check this article.

Spanning Tree – IEEE 802.1d, 802.1w, 802.1s

Spanning tree is used to build a control path between the Ethernet switches in the campus , service provider and data center environment. It prevents data plane loops by creating a tree !

Loop preventation is very crirical for the Ethernet since there is no TTL value or any other loop mitigation mechanism encoded in the Ethernet header.

Loop prevention is achieved by blocking the link which has a higher cost to the root switch in the topology.

802.1d is also known as original spanning tree or legacy spanning tree has been Continue reading

Push and Pull Based Control Plane Mechanisms

Control plane packets are used to build a communication path between the networking devices. In some cases control plane is used to advertise and learn the endpoints.

Imagine a network which consist of these networking devices, in order to crate a graph or tree among them for bridging or routing purpose, control plane protocols are used.

As a network engineer although I keep Application requirements in my mind during a network design, in general layer 4 and above is just boring.

Spanning tree, G.8032, RPR, Trill, SPB, Fabricpath,EAPS, PBB-TE (PBT) are the control plane protocols at the layer 2. They are used to create a communication path , in general a tree. Some of them allow Vlan based load balancing , some of them allow flow based load balancing with ECMP ( Equal Cost Multipath ) or ECT ( Equal Cost Tree ).

But if you read so far, I didn’t mention from reachability information. For the layer 2, reachability for us, Ethernet Mac addresses, Frame relay pdu, ATM cells etc, all of the above protocols are used for Ethernet control plane though.

In general ( SPBM is different ), reachability information is learned through flooding and learning Continue reading

Datacenter Design: Shortest Path Bridging 802.1aq

IEEE 802.1aq Shortest Path Bridging (SPB) uses IS-IS as an underlying control plane mechanism that allows all the links in the topology to be active.

In sum, it supports layer 2 multipath. SPB is used in the datacenter; however, it can also be used in the local area network. In this article, Figure-1 will be used to explain shortest path bridging operation.

Figure-1 – Leaf and Spine Topology

In Figure-1, both leaf and spine nodes run IS-IS to advertise the topological information to each other.

In SPB, IS-IS is used by the bridges to find the shortest path to each other, and it allows the topology to be calculated.

But unlike routing, large scale bridging uses only IS-IS link state protocol for the topological information, not for the reachability information.

This means that the addresses of MAC are not advertised within IS-IS.

Some vendor implementations can also use IS-IS to advertise MAC address information since they only need an additional TLV for this operation. Scalability of IS-IS for the MAC addresses advertisement is questionable for large scale deployment; thus, both BGP for MAC address distribution and IS-IS for physical topology creation might be a good option.

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HSRP, VRRP and GLBP Basics and Comparison

HSRP, VRRP and GLBP are the three commonly used first hop redundancy protocols in local area networks and the data center.

In this post, I will briefly describe them and highlight the major differences. I will ask you a design question so we will discuss in the comment section below.

I am explaining this topic in deep detail in my Instructor Led CCDE and Self Paced CCDE course.

HSRP and GLBP are the Cisco specific protocols but VRRP is an IETF standard. So if the business requirement states that more than one vendor will be used , then VRRP is the best choice to avoid any vendor interoperability issue.

For the default gateway functionality HSRP and VRRP uses one virtual IP corresponds one Virtual Mac address.

GLBP operates in a different way. Clients still use one virtual IP address but more than one virtual mac address is used. So each default gateway switch has its own virtual Mac address but same virtual IP address.

To illustrate this, let’s look at the below picture.

In the above picture, clients use same gateway mac address since the first hop redundancy protocol is HSRP.

If GLBP was in used, on the Continue reading

Inter AS Option C – Design Considerations and Comparison

Inter AS Option C is the most complex, insecure, uncommon, but extremely scalable inter provider MPLS VPN solution.

I am explaining this topic in deep detail in my Instructor Led CCDE and Self Paced CCDE course.

In this post, I will explain how service providers can use Inter AS Option C to assist customers to have an end-to-end MPLS VPN service.

In the Inter AS Option B post, I explained that ASBR routers between the service providers do not keep a VRF table for the VPN customers.

As depicted in the fig.1 (shown below), as for Inter AS Option B, MP-BGP VPNv4 session is set up between service providers’ ASBR PEs.

Figure 1: Inter-AS Option B

As for Inter AS Option B, ASBR routers – the provider-edge devices between the service providers – maintain only the VPN prefixes of the customers in the BGP table.

In fact, I have shown that VPNv4 BGP session has been set up between the ASBRs.

The high-level operational differences between Inter AS Option C and Inter AS Option B are in two folds: one is that ASBRs do not have VRF table; the other is that unlike Continue reading

Russ White – Orhan Ergun CCDE Practical Exam Scenario

I am glad to announce that Russ White and I have been preparing a CCDE Practical Exam ( Lab Exam ) Scenario. This is the most realistic scenario available anywhere. Why? Because it is not only prepared by a CCDE but also by one of the exam founders!

Disclosure : This is not asked in the CCDE exam , but the structure and idea is very similar to what would be found in the exam.

Russ White is one of the CCDE exam founders and the Author of Optimal Routing Design, Practical BGP, Advanced IP Network Design, and many other network design and architecture books. Russ and I have put much effort into preparing this scenario.

I will first present this scenario for the first time in the July CCDE Training class. (You can see from here the topics which I will talk about in the class as well.)

There are already more than 20 people in the class and multiple people will attend the CCDE Exam in August. I am sure this scenario will be an excellent resource for the CCDE candidates.

If you want to be a good network designer as well as a CCDE, it is Continue reading

MPLS Layer 3 VPN Deployment

In this post I will explain MPLS Layer 3 VPN deployment by providing a case study. This deployment mainly will be for green field environment where you deploy network nodes and protocols from scratch. This post doesn’t cover migration from Legacy transport mechanisms such as ATM and Frame Relay migration as it is covered in the separate post on the website.

I am explaining this topic in deep detail in my Instructor Led CCDE and Self Paced CCDE course.

With MPLS, Layer 2 and Layer 3 VPN can be provided and main difference between MPLS Layer 2 and Layer 3 VPN from the deployment point of view is, in MPLS Layer 3 VPN, customer has a routing neighborship with the Service Provider.

In MPLS Layer 2 VPN, Service Provider doesn’t setup a routing neighborship with the customer.

In the below topology I show you basic MPLS network.

Figure – MPLS Network , Components and the Protocols

• CE is the Customer Edge device and generally located at the customer location.
• PE is the Provider Edge Device and located at the Service Provider POP location.
• P is the Provider device and located inside the Service Provider POP location.

Continue reading

PS Core Network Concepts

Most of the educational documents related to PS Core Network start with Call Flows. Attach Call Flow, PDP Context, Paging, etc. Basically that was my problem when I started working in PS Core because the Call Flows include a lot of messages which in turn include a lot of parameters and Information Elements so starting with the Call Flows without knowing at least the Identifiers included in these messages is not the best approach to understand PS Core principles.

This is why this article will be all about the MBB terms that are commonly presented in all Call flows and in most of the MBB talks in general. Once one is comfortable with that, the Call flows will be easy to interpret.

I am bringing some for clarification.

International Mobile Subscriber Identity (IMSI)IMSI

IMSI is a unique Identifier that is allocated to each MS in GSM/UMTS System and stored in SIM Card. (Conforming to ITU E.212 numbering standard)

Temporary Mobile Subscriber Identity (TMSI)

In order to support the subscriber identity confidentiality service the VLRs and SGSNs may allocate Temporary Mobile Subscriber Identities (TMSI) to visiting mobile subscribers.

Below is an MS providing P-TMSI Identity to Network

Continue reading

Evolved Packet Core – Welcome to Long Term Evolution!

As an end user, I am always welcoming the “4G” Signal indicator on my mobile because basically for me this maps to a better Download Speed, good quality VoIP calls (skype, Hangout, Whatsapp, etc) , better Streaming, and HD Videos.

This article is all about the “4G” indicator. I am discussing the Evolved Packet Core together with the EUTRAN, Evolved Universal Terrestrial Radio Access Network Technologies that are realizing the 4G Service offered to end users.

With Data rates above 100 Mbps and latency of milliseconds that enables the best video streaming and online gaming experience; One may think of 4G networks as a replacement for 2G/3G Network which is valid in some cases. However, we see that the decision to “dismantle” 2G/3G is still in the operators roadmaps.

Before we go through the LTE/EPC Network Setup, Let’s list three main definitions and abbreviations that are closely related to 4G.

LTE, Long Term Evolution: LTE is basically the Framework for delivering high-speed Data rates for Mobile and Data Terminals. It started with 3GPP R8 and it is commercially introduced to Markets with term “4G” although “4G” requirements are covered by LTE-Advance (3GPP R10)

EUTRAN, Evolved Universal Terrestrial Radio Continue reading

Junos VRRP with Tracking

VRRP Virtual Router Redundancy Protocol (VRRP) is commonly deployed on corporate networks in order to maintain default gateway redundancy for …

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The post Junos VRRP with Tracking appeared first on Fryguy's Blog.

IS-IS Design considerations on MPLS backbone

Using IS-IS with MPLS require some important design considerations. IS-IS as a scalable link state routing protocol has been used in the Service Provider networks for decades.

In fact, eight of the largest nine Service Providers use IS-IS routing protocol on their network as of today.

If LDP is used to setup an MPLS LSP, important IS-IS design considerations should be carefully understood.

As you might know IS-IS routing protocol uses IS-IS levels for hierarchy.

Similar to other routing protocol, synchronization is one of the consideration. IGP-LDP synchronization is required when MPLS LSP is setup with the LDP protocol. Otherwise routing black holes occur.

One of the important IS-IS design considerations when it is used with MPLS is PE devices loopback IP addresses are not sent into IS-IS Level1 domain in Multi-Level IS-IS design. This problem doesn’t happen in flat IS-IS design since you cannot summarize the prefixes in flat/single level IS-IS deployment.

In IS-IS L1 domain, internal routers only receive ATT (Attached) bit from the L1-L2 router. This bit is used for default route purpose.

If there is more than one L1-L2 router, still only default route is sent into Level1 subdomain/level.

Internal IS-IS Level 1 routers don’t know Continue reading

Your First Public Cloud Deployment Should Be Small

I’ve seen successful public (infrastructure) cloud deployments… but also spectacular failures. The difference between the two usually comes down to whether the team deploying into a public cloud environment realizes they’re dealing with an unfamiliar environment and acts accordingly.

Please note that I’m not talking about organizations migrating their email to Office 365. While that counts as public cloud deployment when an industry analyst tries to paint a rosy picture of public cloud acceptance, I’m more interested in organizations using compute, storage, security and networking public cloud infrastructure.

Tight Wi-Fi integration is key to successful SD-Branch

The promise of SD-Branch is that by collapsing network functionality in branch offices to a unified platform, enterprises can reap benefits in speed of deployment, ease of operation and cost. Since Wi-Fi is a critical piece of local area communications for many branch sites, improved integration, security and management of Wi-Fi is becoming increasingly important to evaluating the benefits of SD-Branch solutions.In branch offices, connected LAN devices and applications must be linked to the Internet via SD-WAN services. By integrating LAN and WAN connectivity, SD-WAN helps to simplify network management with a unified platform as compared to each function having its own unique management console.To read this article in full, please click here

AT&T Down on Low-Band 5G Speed

Intel Throws Down AI Gauntlet With Neural Network Chips

At this year’s Intel AI Summit, the chipmaker demonstrated its first-generation Neural Network Processors (NNP): NNP-T for training and NNP-I for inference. …

Intel Throws Down AI Gauntlet With Neural Network Chips was written by Timothy Prickett Morgan at The Next Platform.

Putting On Demand Price Tags On Datacenter Gear

Traditional datacenter infrastructure suppliers have a complicated relationship with the cloud. …

Putting On Demand Price Tags On Datacenter Gear was written by Jeffrey Burt at The Next Platform.

Cleaning up with apt-get

Running apt-get commands on a Debian-based system is routine. Packages are updated fairly frequently and commands like apt-get update and apt-get upgrade make the process quite easy. On the other hand, how often do you use apt-get clean, apt-get autoclean or apt-get autoremove?These commands clean up after apt-get's installation operations and remove files that are still on your system but are no longer needed – often because the application that required them is no longer installed.[Get regularly scheduled insights by signing up for Network World newsletters.] apt-get clean The apt-get clean command clears the local repository of retrieved package files that are left in /var/cache. The directories it cleans out are /var/cache/apt/archives/ and /var/cache/apt/archives/partial/. The only files it leaves in /var/cache/apt/archives are the lock file and the partial subdirectory.To read this article in full, please click here

Cleaning up with apt-get

Running apt-get commands on a Debian-based system is routine. Packages are updated fairly frequently and commands like apt-get update and apt-get upgrade make the process quite easy. On the other hand, how often do you use apt-get clean, apt-get autoclean or apt-get autoremove?These commands clean up after apt-get's installation operations and remove files that are still on your system but are no longer needed – often because the application that required them is no longer installed.[Get regularly scheduled insights by signing up for Network World newsletters.] apt-get clean The apt-get clean command clears the local repository of retrieved package files that are left in /var/cache. The directories it cleans out are /var/cache/apt/archives/ and /var/cache/apt/archives/partial/. The only files it leaves in /var/cache/apt/archives are the lock file and the partial subdirectory.To read this article in full, please click here

A64FX Arm Chip Gets A Big Push From Cray

There are many good processors out there, but there are few that are excellent and elegant inasmuch as they are co-designed for specific workloads and then do them very well. …

A64FX Arm Chip Gets A Big Push From Cray was written by Timothy Prickett Morgan at The Next Platform.

Space-sourced power could beam electricity where needed

Capturing solar energy in space and then beaming it down to Earth could provide consistent electricity supplies in places that have never seen it before. Should the as-yet untested idea work and be scalable, it has applications in IoT-sensor deployments, wireless mobile network mast installs and remote edge data centers.The radical idea is that super-efficient solar cells collect the sun’s power in space, convert it to radio waves, and then squirt the energy down to Earth, where it is converted into usable power. The defense industry, which is championing the concept, wants to use the satellite-based tech to provide remote power for forward-operating bases that currently require difficult and sometimes dangerous-to-obtain, escorted fuel deliveries to power electricity generators.To read this article in full, please click here