TCP Protocol: Flow Control

In the last two posts here and here, we have discussed how TCP stack initiates a TCP 3-way handshake and create the appropriate Transmission Control Block for the data to flow reliably. We knew that the main function of the 3-way handshaking is to exchange the sequence numbers, MSS, receive window and other parameters between two endpoints. In this post, we will discuss the concept of flow control and how TCP will reliably make sure that data segments are delivered to the other end in-order for the correct data reassembly using the sequence and acknowledgement numbers and sliding windows. Let’s …

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Classic DC and M-LAG

In the pervious post we talked  about BGP in Data Center and how it is a topic of discussion in between the DC and the SP arenas. In this post I will start explaining some classic DC design and laying its shortage which will engage the SP gurus with us, as well it will make sure that we all on the same page for the DC gurus. So let’s start to engage the SP gurus with basic enterprise and DC concepts. Basic Ethernet world in LAN would go like this switches forward frames based on detestation MAC address, the MAC address learning …

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BGP in the Data Center

If you think that BGP is a Server Provider (SP) only protocol and is not your business in the data center, then better think again because BGP is coming to your territory. Traditionally for Enterprises and DCs; BGP commonly took part at the Internet edge in multi-homing scenarios (the internet from multiple ISPs) where BGP provided such networks with better control of upstream and downstream internet traffic as well as some other extra redundancy features as compared to basic default/static routing. With the current Cloud evolution and demands, BGP can generally be used in many different solutions in the DC domain. …

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What is 6PE?


6PE is one of the efficient solutions for interconnecting IPv6 islands over an IPv4-only MPLS cloud without needing to drastically change the core network design by having all your Core routers dual-stacked 6PE does not use manual standard tunnels, it provides an alternative where all tunnels are established dynamically eliminating the need to configure and maintain tunnels. The approach requires that the edge routers connected to IPv6 islands be Dual Stack Multiprotocol-BGP-speaking routers. while the core routers can only run IPv4 MPLS Configuring 6PE is has a lot of similarities with configuring  IPv4 VPNs as both use MP-BGP to distribute non-IPv4 reachability …

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CCIE SPv4.1 Blueprint Resources

The CCIE SP SME team has put a comprehensive list of study resources for the new CCIE SP4.1 blueprint. The complied list is in a spreadsheet designed to help you quickly find what you are looking for by organizing the content according to the exam topics. This is a very good resource for finding good information regardless of the exam. You can download the spreadsheet @ CCIE_SP_version4.1_prep_resources.xlsx. Find out more information at Cisco Learning Network.

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TCP Protocol: TCP 3-way handshaking #2


In the last post, we have explained the TCP 3-way handshaking from an abstract point of view, and knew that one of the main functions of this handshaking is to exchange and synchronize some parameters for the TCP connection endpoints to facilitate its job. We also knew that two of the main parameters that the end-points exchange in the TCP 3-way handshaking are the SEQUENCE and ACK numbers. Today, we will continue the 3-way handshaking process in more details. Above is a TCP capture file which I downloaded from “Wireshark” wiki page that shows 3 packets in sequence between two end-hosts. From …

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