Feedback: Microsoft Azure Networking

Numerous networking engineers found my cloud webinars (AWS, Azure) useful when preparing for a cloud migration project. Here’s what one of them wrote:

We are beginning to migrate some of our offerings to Microsoft Azure and I need to get up to speed with Azure products. I found this webinar very informative, and Ivan explained the concepts in a clear manner and easy to follow along. I would recommend watching these webinars and then read Microsoft documentation to get a thorough understanding.

Want to have some hands-on work sprinkled on top of that? You’ll find deployment examples in the Networking in Public Clouds GitHub repository.

Alternatives to IBGP within Multihomed Sites

Two weeks ago I explained why you might want to run IBGP between CE-routers on a multihomed site. One of the blog readers didn’t like my ideas:

In such a small deployment I assume that both ISPs offer transit, so that both CEs would get a default route from their upstream.

In this case I would not iBGP the CEs together but have HSRP running on the two CEs and track the uplink (interface and/of BGP session) to determine the active gateway.

Let’s see what could possibly go wrong with that design.

Alternatives to IBGP within Multihomed Sites

Two weeks ago I explained why you might want to run IBGP between CE-routers on a multihomed site. One of the blog readers didn’t like my ideas:

In such a small deployment I assume that both ISPs offer transit, so that both CEs would get a default route from their upstream.

In this case I would not iBGP the CEs together but have HSRP running on the two CEs and track the uplink (interface and/of BGP session) to determine the active gateway.

Let’s see what could possibly go wrong with that design.

Suspending Devices in netlab Labs

A networking engineer tired of waiting for network devices to start sent me this question:

Can you suspend VMs in netlab? I use this trick in vSphere with CSR1Kv.

TL&DR: Maybe. Probably not.

Suspending Devices in netlab Labs

A networking engineer tired of waiting for network devices to start sent me this question:

Can you suspend VMs in netlab? I use this trick in vSphere with CSR1Kv.

TL&DR: Maybe. Probably not.

Video: Packet Buffers in Data Center ASICs

A few years ago, we were fortunate enough to have Pete Lumbis talking about ASICs for Networking Engineers as part of the Data Center Fabric Architectures webinar.

One of the topics he couldn’t possible skip was the question of how many packet buffers one needs in a data center switch.

Video: Packet Buffers in Data Center ASICs

A few years ago, we were fortunate enough to have Pete Lumbis talking about ASICs for Networking Engineers as part of the Data Center Fabric Architectures webinar.

One of the topics he couldn’t possibly skip was the question of how many packet buffers one needs in a data center switch.

How Many Spines Should a Leaf-and-Spine Fabric Have?

One of my readers sent me a question along these lines:

How do we determine the number of spines needed in a leaf-and-spine fabric? It’s easy to calculate the number of leaf nodes from the required number of server ports, and two spines give you the redundancy. Does it make sense to have more spines if two are good enough from the capacity perspective?

There are at least two factors to consider:

How Many Spines Should a Leaf-and-Spine Fabric Have?

One of my readers sent me a question along these lines:

How do we determine the number of spines needed in a leaf-and-spine fabric? It’s easy to calculate the number of leaf nodes from the required number of server ports, and two spines give you the redundancy. Does it make sense to have more spines if two are good enough from the capacity perspective?

There are at least two factors to consider:

Measuring Virtual Network Device Boot Times

A senior engineer at Juniper Networks wasn’t happy with me mentioning resource hogs and Junos platforms in the same statement. Instead of engaging in never-ending angels dancing on pins deliberations comparing the virtues of Junos with other network operating systems, I decided to throw a bit of real-life data into the mix – I created a simple script that measures:

• The time it takes to execute vagrant up to start a single network device.
• The time it takes to deploy simple initial configuration on that device.

Measuring Virtual Network Device Boot Times

A senior engineer at Juniper Networks wasn’t happy with me mentioning resource hogs and Junos platforms in the same statement. Instead of engaging in never-ending angels dancing on pins deliberations comparing the virtues of Junos with other network operating systems, I decided to throw a bit of real-life data into the mix – I created a simple script that measures:

• The time it takes to execute vagrant up to start a single network device.
• The time it takes to deploy simple initial configuration on that device.

Some Operations Are Not Worth Automating

Ish wrote an interesting comment on my Network Automation Expert Beginners blog post. He started with:

[Our network has] about 40 sites, but we don’t do total refresh cycles in bulk, just as needed. Everything we do is sporadic, and I’m trying to see the ROI on learning automation for things that are done once in a while that don’t take much time to do manually anyway.

There are two aspects to this part of his comment:

Some Operations Are Not Worth Automating

Ish wrote an interesting comment on my Network Automation Expert Beginners blog post. He started with:

[Our network has] about 40 sites, but we don’t do total refresh cycles in bulk, just as needed. Everything we do is sporadic, and I’m trying to see the ROI on learning automation for things that are done once in a while that don’t take much time to do manually anyway.

There are two aspects to this part of his comment:

Start Multiple netlab Labs on the Same Server

A heavy netlab user sent me an email along these lines:

We’re running multiple labs in parallel on the same server, and we’re experiencing all sorts of clashes like overlapping management IP addresses. We “solved” that by using static device identifiers in our labs, but I’m wondering if there’s a better way of doing it?

That’s exactly the sort of real-life challenges I love working on, so it wasn’t hard to get me excited, and the results are bundled in netlab release 1.5.

Start Multiple netlab Labs on the Same Server

A heavy netlab user sent me an email along these lines:

We’re running multiple labs in parallel on the same server, and we’re experiencing all sorts of clashes like overlapping management IP addresses. We “solved” that by using static device identifiers in our labs, but I’m wondering if there’s a better way of doing it?

That’s exactly the sort of real-life challenges I love working on, so it wasn’t hard to get me excited, and the results are bundled in netlab release 1.5.

Worth Reading: On ChatGPT

One of the best descriptions of what ChatGPT does and what it cannot do I found so far comes from an ancient and military historian. The what is ChatGPT and what is an essay parts are a must-read, the preparing to be disrupted conclusion is pure gold:

I do think there are classrooms that will be disrupted by ChatGPT, but those are classrooms where something is already broken.

I can’t help but think of the never-ending brouhaha about exam brain dumps.

Worth Reading: On ChatGPT

One of the best descriptions of what ChatGPT does and what it cannot do I found so far comes from an ancient and military historian. The what is ChatGPT and what is an essay parts are a must-read, the preparing to be disrupted conclusion is pure gold:

I do think there are classrooms that will be disrupted by ChatGPT, but those are classrooms where something is already broken.

I can’t help but think of the never-ending brouhaha about exam brain dumps.

Video: Link State Routing Protocol Basics

The Routing Protocols Overview part of How Networks Really Work webinar introduced the concepts of distance-vector and link-state routing protocols. Next step: the basics of link-state routing protocols.

Video: Link State Routing Protocol Basics

The Routing Protocols Overview part of How Networks Really Work webinar introduced the concepts of distance-vector and link-state routing protocols. Next step: the basics of link-state routing protocols.

Feedback: Designing Active/Active and Disaster Recovery Data Centers

In the Designing Active-Active and Disaster Recovery Data Centers I tried to give networking engineers a high-level overview of challenges one might face when designing a highly-available application stack, and used that information to show why the common “solutions” like stretched VLANs make little sense if one cares about application availability (as opposed to auditor report). Some (customer) engineers like that approach; here’s the feedback I received not long ago:

As ever, Ivan cuts to the quick and provides not just the logical basis for a given design, but a wealth of advice, pointers, gotchas stemming from his extensive real-world experience. What is most valuable to me are those “gotchas” and what NOT to do, again, logically explained. You won’t find better material IMHO.

Please note that I’m talking about generic multi-site scenarios. From the high-level connectivity and application architecture perspective there’s not much difference between a multi-site on-premises (or collocation) deployment, a hybrid cloud, or a multicloud deployment.