Christopher Hart wrote a great blog post explaining the fundamentals of how packet load balancing works on network devices. Enjoy.
For more details, watch the Multipath Forwarding part of Advanced Routing Protocol Topics section of How Networks Really Work webinar.
Christopher Hart wrote a great blog post explaining the fundamentals of how packet load balancing works on network devices. Enjoy.
For more details, watch the Multipath Forwarding part of Advanced Routing Protocol Topics section of How Networks Really Work webinar.
Here’s one of the secrets to AWS’s unprecedented scale and financial success: they figured out very early on that some services are not worth delivering. Most everyone else believes in building snowflake single-customer solutions to solve imaginary problems, effectively losing money while doing so.
Here’s one of the secrets to AWS’s unprecedented scale and financial success: they quickly figured out that some services are not worth delivering. Most everyone else believes in building snowflake single-customer solutions to solve imaginary problems, effectively losing money while doing so.
A friend of mine sent me a link to a lengthy convoluted document describing the 17-step procedure (with the last step having 10 micro-steps) to follow if you want to run NSX manager on top of N-VDS, or as they call it: Deploy a Fully Collapsed vSphere Cluster NSX-T on Hosts Running N-VDS Switches1.
You might not be familiar with vSphere networking and the way NSX-T uses that (in which case I can highly recommend vSphere and NSX webinars), so here’s a CliffsNotes version of it: you want to put the management component of NSX-T on top of the virtual switch it’s managing, and make it accessible only through that virtual switch. What could possibly go wrong?
A friend of mine sent me a link to a lengthy convoluted document describing the 17-step procedure (with the last step having 10 micro-steps) to follow if you want to run NSX manager on top of N-VDS, or as they call it: Deploy a Fully Collapsed vSphere Cluster NSX-T on Hosts Running N-VDS Switches1.
You might not be familiar with vSphere networking and the way NSX-T uses that (in which case I can highly recommend vSphere and NSX webinars), so here’s a CliffsNotes version of it: you want to put the management component of NSX-T on top of the virtual switch it’s managing, and make it accessible only through that virtual switch. What could possibly go wrong?
I got into an interesting debate after I published the Anycast Works Just Fine with MPLS/LDP blog post, and after a while it turned out we have a slightly different understanding what anycast means. Time to fall back to a Wikipedia definition:
Anycast is a network addressing and routing methodology in which a single destination IP address is shared by devices (generally servers) in multiple locations. Routers direct packets addressed to this destination to the location nearest the sender, using their normal decision-making algorithms, typically the lowest number of BGP network hops.
Based on that definition, any transport technology that allows the same IP address or prefix to be announced from several locations supports anycast. To make it a bit more challenging, I would add “and if there are multiple paths to the anycast destination that could be used for multipath forwarding1, they should all be used”.
I got into an interesting debate after I published the Anycast Works Just Fine with MPLS/LDP blog post, and after a while it turned out we have a slightly different understanding what anycast means. Time to fall back to a Wikipedia definition:
Anycast is a network addressing and routing methodology in which a single destination IP address is shared by devices (generally servers) in multiple locations. Routers direct packets addressed to this destination to the location nearest the sender, using their normal decision-making algorithms, typically the lowest number of BGP network hops.
Based on that definition, any transport technology that allows the same IP address or prefix to be announced from several locations supports anycast. To make it a bit more challenging, I would add “and if there are multiple paths to the anycast destination that could be used for multipath forwarding1, they should all be used”.
When I wrote the Why Does Internet Keep Breaking? blog post a few weeks ago, I claimed that FRR still uses single-threaded routing daemons (after a too-cursory read of their documentation).
Donald Sharp and Quentin Young politely told me I was an idiot I should get my facts straight, I removed the offending part of the blog post, promised to write another one going into the details, and Quentin improved the documentation in the meantime, so here we are…
When I wrote the Why Does Internet Keep Breaking? blog post a few weeks ago, I claimed that FRR still uses single-threaded routing daemons (after a too-cursory read of their documentation).
Donald Sharp and Quentin Young politely told me I was an idiot I should get my facts straight, I removed the offending part of the blog post, promised to write another one going into the details, and Quentin improved the documentation in the meantime, so here we are…
Using custom templates to test IP anycast with MPLS was fun, but as I got into interesting discussions focusing on convoluted details, I found myself going through the same set of steps too many times.
It started with the need to specify individual devices in netlab config command to create new loopback interfaces on anycast servers but not on any other device in the lab. Wouldn’t it be nice to have a group of devices (similar to Ansible groups) that one could use in the limit parameter of netlab config?
Using custom templates to test IP anycast with MPLS was fun, but as I got into interesting discussions focusing on convoluted details, I found myself going through the same set of steps too many times.
It started with the need to specify individual devices in netlab config command to create new loopback interfaces on anycast servers but not on any other device in the lab. Wouldn’t it be nice to have a group of devices (similar to Ansible groups) that one could use in the limit parameter of netlab config?
It took more than seven years to publish an obvious fact as an RFC: IPv6 extension headers are a bad idea (RFC 9098 has a much more polite title or it would never get published).
It took more than seven years to publish an obvious fact as an RFC: IPv6 extension headers are a bad idea (RFC 9098 has a much more polite title or it would never get published).
Another must-read masterpiece by Julia Evans: how to get useful answers to your questions.
Another must-read masterpiece by Julia Evans: how to get useful answers to your questions.
After a brief coverage of the theoretical aspects of network addressing, it’s time to pay a brief visit to the early data-link-layer addressing solutions, from one address per datagram/frame (SDLC, HDLC) and ignore this address (PPP) to no address on P2P links (SLIP).
After a brief coverage of the theoretical aspects of network addressing, it’s time to pay a brief visit to the early data-link-layer addressing solutions, from one address per datagram/frame (SDLC, HDLC) and ignore this address (PPP) to no address on P2P links (SLIP).
One of my readers sent me this age-old question:
Is there a real difference in the underlying hardware of switches and routers in terms of the traffic processing chips and their capabilities in terms of routing and switching (or should I say only switching)?
Let’s get the terminology straight. Router is a technical term for a device that forwards packets based on network layer information. Switch is a marketing term for a device that does something with packets.
Rephrasing the question: is there a hardware difference between a box marketed as a router and another box marketed as a layer-3 switch?
TL&DR: Yes.
Doing packet forwarding at high speeds is expensive, and simpler forwarding pipeline results in cheaper (or faster) silicon.
If you don’t need complex high-speed functionality (like a thousand interface output queues with per-flow classifier), you create a simpler ASIC and call the device a switch. If you thrive on overpriced products, you create as complex an ASIC as you can make it and call the device using it a router. EX9200 is an obvious counterexample, but then Juniper always looked like DEC of networking to me.
There’s even a difference in capabilities between spine- and leaf data Continue reading
One of my readers sent me this age-old question:
Is there a real difference in the underlying hardware of switches and routers in terms of the traffic processing chips and their capabilities in terms of routing and switching (or should I say only switching)?
Let’s get the terminology straight. Router is a technical term for a device that forwards packets based on network layer information. Switch is a marketing term for a device that does something with packets.
Rephrasing the question: is there a hardware difference between a box marketed as a router and another box marketed as a layer-3 switch?
TL&DR: Yes.