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Category Archives for "Networking"

The Languages Which Almost Became CSS

The Languages Which Almost Became CSS

This was adapted from a post which originally appeared on the Eager blog. Eager has now become the new Cloudflare Apps.

In fact, it has been a constant source of delight for me over the past year to get to continually tell hordes (literally) of people who want to – strap yourselves in, here it comes – control what their documents look like in ways that would be trivial in TeX, Microsoft Word, and every other common text processing environment: “Sorry, you’re screwed.”

— Marc Andreessen 1994

When Tim Berners-Lee announced HTML in 1991 there was no method of styling pages. How a given HTML tag was rendered was determined by the browser, often with significant input from the user’s preferences. To Continue reading

Troubleshooting Cisco Network Elements with the USE Method

I want to draw some attention to a new document I've written titled “Troubleshooting Cisco Network Elements with the USE Method". In it, I explain how I've taken a model for troubleshooting a complex system-the USE Method, by Brendan Gregg-and applied it to Cisco network devices. By applying the USE Method, a network engineer can perform methodical troubleshooting of a network element in order to determine why the NE is not performing/acting/functioning as it should.

Troubleshooting Cisco Network Elements with the USE Method

The USE Method is a model for troubleshooting a system that is in distress when you don't know exactly what the nature of the problem is. For example, if users within a specific part of your network are complaining of slowness, disconnects and poor application performance, you can probably isolate your troubleshooting to 2-3 switches or routers. However, since the problem description is so vague (we all love the “it's slow!

EVPN-VXLAN lab – basic L2 switching

My EVPN-VXLAN lab topology:

There is IP Fabric in DC1 (2 vMX and 2 vQFX), and 2 vMX_v14 to emulate CE devices. Each CE device connected to EVPN via LACP LAG ae0 (EVPN Active-Active ethernet segment on service side). vMX_old-1 also has sigle-homed interface ge-0/0/4 (just to show you the difference).
Each CE device split into two logical systems for more convenient testing of routing functionality (global device context for Vlan100 and logical-system second for Vlan200). You could also use virtual-router routing instances for that, if you prefer this way. The rest of CE config is pretty self-explanatory:

alex@MX1# show interfaces
ge-0/0/0 {
    description vMX1;
    gigether-options {
        802.3ad ae0;
    }
}
ge-0/0/1 {
    description vMX2;
    gigether-options {
        802.3ad ae0;
    }
}
ge-0/0/4 {
    description vMX1_second;
    flexible-vlan-tagging;
    encapsulation flexible-ethernet-services;
    mac 00:46:d3:04:fe:06;
}
ae0 {
    description to_MC-LAG_vMX;
Continue reading

IDC: SD-WAN growth is exploding for at least the next 5 years

As network pros rely more and more on SD-WAN to streamline connections among enterprise sites, the market for this technology will balloon from $225 million in 2015 to $1.19 billion by the end of this year, according to IDC.Over the next five years, SD-WAN sales will grow at a 69% compound annual growth rate, hitting $8.05 billion in 2021, according to IDC’s Worldwide SD-WAN Forecast, 2017–2021.As businesses adopt what IDC calls “third-platform” technologies such as cloud, mobile, big data and analytics, they put increased strain on the network. As organizations look to better connect their remote and branch office employees and provide them better quality network services, SD-WAN will continue to grow.To read this article in full or to leave a comment, please click here

IDC: SD-WAN growth is exploding for at least the next 5 years

As network pros rely more and more on SD-WAN to streamline connections among enterprise sites, the market for this technology will balloon from $225 million in 2015 to $1.19 billion by the end of this year, according to IDC.Over the next five years, SD-WAN sales will grow at a 69% compound annual growth rate, hitting $8.05 billion in 2021, according to IDC’s Worldwide SD-WAN Forecast, 2017–2021.As businesses adopt what IDC calls “third-platform” technologies such as cloud, mobile, big data and analytics, they put increased strain on the network. As organizations look to better connect their remote and branch office employees and provide them better quality network services, SD-WAN will continue to grow.To read this article in full or to leave a comment, please click here

Worth Reading: LinkedIn passes an IPv6 milestone

Since we enabled IPv6 on our mail servers in 2013 and then on our web site in 2014, we have seen increased growth of our external IPv6 traffic. We are currently working on enabling IPv6 on our all of our internal networks and applications in order to begin removing IPv4 internally, beginning in 2018. The external network and public services will still support IPv4 (for compatibility with legacy clients) for years to come, but we anticipate the proportion of our external traffic served over IPv6 to only increase. The community has seen tangible benefits from serving content over IPv6 compared to IPv4. We, too, see some performance improvements on IPv6. —LinkedIn Engineering Blog

The post Worth Reading: LinkedIn passes an IPv6 milestone appeared first on rule 11 reader.

Cisco’s Nexus 9516 review: About line rate

Much ink has been spilled on the topic of what constitutes true “line rate,” and in the past we’ve advocated offering traffic at, and only at, 100.00 percent of theoretical line rate to determine if frame loss exists. However, the distinction between 99.99 percent (which we used in these tests) and 100.00 percent load is not all that meaningful, especially at higher Ethernet speeds, for a couple of reasons. First, Ethernet is inherently an asynchronous technology, meaning each device (in this case, the device under test and the test instrument) uses one or more of its own free-running clocks, without synchronization. Thus, throughput measurements may just be artifacts of minor differences in the speeds of clock chips, not descriptions of a system’s fabric capacity.To read this article in full or to leave a comment, please click here

Cisco’s Nexus 9516 review: About line rate

Much ink has been spilled on the topic of what constitutes true “line rate,” and in the past we’ve advocated offering traffic at, and only at, 100.00 percent of theoretical line rate to determine if frame loss exists. However, the distinction between 99.99 percent (which we used in these tests) and 100.00 percent load is not all that meaningful, especially at higher Ethernet speeds, for a couple of reasons. First, Ethernet is inherently an asynchronous technology, meaning each device (in this case, the device under test and the test instrument) uses one or more of its own free-running clocks, without synchronization. Thus, throughput measurements may just be artifacts of minor differences in the speeds of clock chips, not descriptions of a system’s fabric capacity.To read this article in full or to leave a comment, please click here

Cisco’s Nexus 9516 review: About line rate

Much ink has been spilled on the topic of what constitutes true “line rate,” and in the past we’ve advocated offering traffic at, and only at, 100.00 percent of theoretical line rate to determine if frame loss exists. However, the distinction between 99.99 percent (which we used in these tests) and 100.00 percent load is not all that meaningful, especially at higher Ethernet speeds, for a couple of reasons. First, Ethernet is inherently an asynchronous technology, meaning each device (in this case, the device under test and the test instrument) uses one or more of its own free-running clocks, without synchronization. Thus, throughput measurements may just be artifacts of minor differences in the speeds of clock chips, not descriptions of a system’s fabric capacity.To read this article in full or to leave a comment, please click here

Cisco Nexus 9516 review: How we did it

The device under test for this project was the Cisco Nexus 9516 data center core switch/router, a 16-slot chassis equipped with 1,024 50-gigabit Ethernet interfaces and two supervisor modules. Cisco equipped the switch with its N9K-X9732C-EX line cards, each of which offers 32, 64, or 128 ports of 100-, 50-, and 25-gigabit Ethernet capacity.The traffic generator/analyzer was Spirent TestCenter equipped with its 10/25/40/50/100G MX3 modules. The Spirent instrument has a measurement precision of +/- 2.5 nanoseconds.To read this article in full or to leave a comment, please click here

Cisco Nexus 9516 review: How we did it

The device under test for this project was the Cisco Nexus 9516 data center core switch/router, a 16-slot chassis equipped with 1,024 50-gigabit Ethernet interfaces and two supervisor modules. Cisco equipped the switch with its N9K-X9732C-EX line cards, each of which offers 32, 64, or 128 ports of 100-, 50-, and 25-gigabit Ethernet capacity.The traffic generator/analyzer was Spirent TestCenter equipped with its 10/25/40/50/100G MX3 modules. The Spirent instrument has a measurement precision of +/- 2.5 nanoseconds.To read this article in full or to leave a comment, please click here

Cisco Nexus 9516 data center switch aces a grueling high-density stress test

How many ports are enough at the core of the data center? How does 1,024 sound?That’s the configuration we used to assess Cisco Systems’ Nexus 9516 data center core switch. In this exclusive Clear Choice test, we assessed the Cisco data center core switch with more than 1,000 50G Ethernet ports. That makes this by far the largest 50G test, and for that matter the highest-density switch test, Network World has ever published.As its name suggests, the Nexus 9516 accepts up to 16 N9K-X9732C-EX line cards, built around Cisco’s leaf-and-spine engine (LSE) ASICs. These multi-speed chips can run at 100G rates, for up to 512 ports per chassis; 50G rates for up to 1,024 ports; or 25G rates for up to 2,048 ports. We picked the 50G rate, and partnered with test and measurement vendor Spirent Communications to fully load the switch’s control and data planes.To read this article in full or to leave a comment, please click here

Cisco Nexus 9516 data center switch aces a grueling high-density stress test

How many ports are enough at the core of the data center? How does 1,024 sound?That’s the configuration we used to assess Cisco Systems’ Nexus 9516 data center core switch. In this exclusive Clear Choice test, we assessed the Cisco data center core switch with more than 1,000 50G Ethernet ports. That makes this by far the largest 50G test, and for that matter the highest-density switch test, Network World has ever published.As its name suggests, the Nexus 9516 accepts up to 16 N9K-X9732C-EX line cards, built around Cisco’s leaf-and-spine engine (LSE) ASICs. These multi-speed chips can run at 100G rates, for up to 512 ports per chassis; 50G rates for up to 1,024 ports; or 25G rates for up to 2,048 ports. We picked the 50G rate, and partnered with test and measurement vendor Spirent Communications to fully load the switch’s control and data planes.To read this article in full or to leave a comment, please click here

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