Shulou(Shulou.com)06/01 Report--

Although it used to be Citrix ERM's software SE, the reality and career anxiety prompted me to learn as much about products as possible, such as XenMobile, such as XenServer, such as Octoblu, such as NetScaler, such as SD-WAN.

Interestingly, it wasn't until I left Citrix that I first came into contact with SD-WAN and made a PoC. Compared to NetScaler, I think SD-WAN is easier to use (I have forgotten OSPF and BGP, and I don't remember Spanning Tree very much, but I think I can do it in a day when I really need it), and it does solve the rigid needs of users, so this product is really worth promoting.

Of course, as my style, something that hasn't been tested, I won't tell you how good it is. Do short-term sales may not like, do long-term sales may be more recognized. For me, when a project comes down, the client and you become buddies, and any effort you spend is worth it. Well, it's just that stupid.

All right, let's get back to the book. I recently tested SD-WAN. Just like introducing PVS to users before, I finally got the first-hand data to verify it. In this essay, I will give a brief introduction to the points that I am most concerned about in the test.

In this test, a pair of SD-WAN devices were deployed, which were configured and monitored using the SD-WAN console and the SDWAN management center. Each of the two sites uses a dedicated line and two Internet lines. Limited to space, I will post the tests that I think are more characteristic.

Data retransmission is reliable and stable. Important data can be transmitted simultaneously on multiple lines on a first-come-first-served basis.

In this way, several lines with sufficient bandwidth but insufficient reliability and stability can be turned into reliable and stable virtual lines.

Preferred transmission, bandwidth recombination. SDWAN has its own line quality inspection, which transmits the highest priority data using the best line according to QoS. At the same time, the bandwidth of several lines can be superimposed seamlessly, so there is no need to artificially divide the traffic on different lines by routing or other means. This means that traffic can be automatically regulated between lines according to quality, and make full use of all available bandwidth, eliminating the waste of backup lines and the impact of manual switching.

We use iperf to simulate the flow pressure. A single process seems to use only about 50m of traffic, so multiple are enabled at the same time until the consumed traffic far exceeds the capacity of a single line and is close to the sum of all line capacity.

In the actual test, it is also found that the quality of Internet lines sometimes exceeds the quality of dedicated lines, which shows that more traffic chooses Internet lines for transmission.

The conversation continues and the business continues. In the past, when pre-sales, Citrix SDWAN will be introduced to users and other different places. Whether it is policy routing switching or other schemes, the existing network connection will certainly be disconnected in the event of a line failure. Because the SDWAN of Citrix re-encapsulates the data packet and uses connectionless UDP to transmit, the device is responsible for the integrity of the data packet, so there is no need to re-establish the TCP connection.

During the test, we disconnect the lines one by one, while continuously testing the data connection. The data connection remains unaffected until the last line is left.

I don't bother to write this part of traffic compression optimization, more than one can do it. What I want to point out is that for small and medium-sized deployments, these two parts can be done through one device. After all, the branch office does not have many places to stack a pile of equipment, "save a U, it is a U".

In order to test stability and reliability, the dedicated line is simply disabled and only the Internet line is used to run the business. It turns out there's nothing wrong with it... In order to illustrate the performance, I specially took a few pictures:

The black line at the top of the picture is the collection of line bandwidth represented by the following different color lines. It is also the bandwidth used by the final virtual link.

The use of SDWAN can optimize the delay of the line. Because the best line transmission is selected among multiple lines, the delay of the final data connection becomes the minimum; due to the reduction of TCP transmission retransmission and transmission window adjustment, the actual delay is lower than the minimum value of each line.

There has been a large packet loss on the Internet lines used, which is not long, but it is enough to affect the quality of the network. It is this situation that causes most users to choose a relatively stable dedicated line, even if it is so expensive. After the packets are re-encapsulated by SDWAN, only the dropped packets rather than all the packets transmitted at one time are retransmitted, so the adverse impact of line packet loss is greatly reduced.

For line jitter, it often affects the transmission quality, although it does not seem to be as severe as delay and packet loss, but the window adjustment also affects the effective use of bandwidth. The role of SDWAN reduces the impact of jitter, and the jitter lines of virtual links are thus hidden under the jitter lines of multiple lines.

It is really difficult for them to entrust the important task of the original dedicated line to two unreliable Internet lines. So even with SDWAN's own line quality assessment, there are a lot of Bad evaluations of Internet lines when they are busy. But in the end, the virtual link between the two lines becomes a black line at the level of Good.

The saving of SDWAN to the circuit and the improvement to the quality are shown simply and intuitively.

It can be used from data center to branch office, data center to cloud, this cloud to other clouds, domestic cloud to international cloud.

Growing up, homesickness is like a pair of SD-WAN, I am at this end, you are at the other end, across thousands of rivers and mountains, but forever continuous.

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