Mobile Broadband Ecosystem
Mobile Broadband… You might have heard this term before, possibly in an ISP environment. The term has always represented a name of a department within a mobile operator or a vendor organization. It is always there in profile description for telecom professionals. It is everywhere actually when it comes to a certain ecosystem or framework that delivers Internet Service using Mobile Network.
To have a great understanding of SP Networks, you can check my new published “Service Provider Networks Design and Architecture Perspective” Book.
Let me bring the Wikipedia definition followed with a small note …
Mobile broadband is the marketing term for wireless Internet access through a portable modem, mobile phone, USB wireless modem, tablet or other mobile devices.
Definition is true but the note here is that you can’t rely solely on google to understand the MBB related technologies (EDGE, UMTS, 4G/LTE, etc.) because what is in google is mainly the marketing articles and the vendor specific publications which is fine but as a lesson learned, one need always to understand the technology concept decoupled from vendors influence.
The good thing is that the whole knowledge, principles, & Service descriptions for Mobile Broadband is Continue reading
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.
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.
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
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 …
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.
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