L3 fabric DC -The underlay Network (BGP) -part2

Screen Shot 2016-04-23 at 19.17.28

In the previous post, we laid the foundation of L3 fabric DC In this post we will discuss the underlay network which mainly provide IP reachability plus ECMP capability, here BGP would play a role in your DC next to the 3 other that we discussed one of the previous posts. For the sake of simplicity think of this L3 fabric like group of routers connected physically in spine and leaf topology (3 stages CLOS leaf-spine-leaf), our target is to provide IP connectivity. How many Leaf/TOR you would have? This might vary based on the size of your DCs some would …

Read More »

L3 fabric DC -The underlay Network -Part1

In the previous posts we have discussed the classic DC designs and the M-LAG solution. In this post we will cover the basic L3 fabric DC, you might never heard of it or you think that’s a solution for massive scale DC, yes the massive DC in the world would be running L3 fabric but nowadays more and more customers are moving to it. What about the Vendor specific solutions Cisco fabric-path, Cisco FEX, Juniper Q-fabric, Juniper VCF. All are decent solution but the problem with all of is they are tagged as “closed Ethernet fabric” or “turn-key Ethernet fabric”. That means they are closed so once …

Read More »

TCP Protocol: Slow Start

stevens4

In the last post we explained the basic idea of using sequence and acknowledgement numbers to track how many bytes were sent and received. We also has encountered the term “slow start” and elaborated how TCP uses this concept on the server to send few segments of data to the receiver instead of sending the full receive window (RWIN) of the receiver and congest the path between them. Today, we will try to dive into slow start and, as every previous post, relate the theoretical part with a real capture file. Have you ever wondered, why the first few seconds of any …

Read More »

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 …

Read More »

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 …

Read More »

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. …

Read More »