ipSpace.net Subscription for System Administrators

One of our subscribers sent me this question:

I am a system administrator working primarily on server/storage virtualization. How would you recommend I take full advantage of the subscription while not being in networking full-time?

Let’s start with the webinars focused on technologies and fundamentals:

• If you’re interested in networking fundamentals, go through the first part of How Networks Really Work — stop when you feel it’s turning into a deep dive.
• As a sysadmin, you probably work within a data center environment. Data Center Infrastructure for Networking Engineers is another fundamentals-focused webinar worth exploring.
• Involved in multi-site DC deployments? Check out the Data Center Interconnects and Designing Active-Active and Disaster Recovery Data Centers.
• On the storage side, there’s Hyper-Converged Infrastructure Deep Dive and The Network Impact of NVMe over Fabrics (NVMe-oF).

ipSpace.net Subscription for System Administrators

One of our subscribers sent me this question:

I am a system administrator working primarily on server/storage virtualization. How would you recommend I take full advantage of the subscription while not being in networking full-time?

Let’s start with the webinars focused on technologies and fundamentals:

• If you’re interested in networking fundamentals, go through the first part of How Networks Really Work — stop when you feel it’s turning into a deep dive.
• As a sysadmin, you probably work within a data center environment. Data Center Infrastructure for Networking Engineers is another fundamentals-focused webinar worth exploring.
• Involved in multi-site DC deployments? Check out the Data Center Interconnects and Designing Active-Active and Disaster Recovery Data Centers.
• On the storage side, there’s Hyper-Converged Infrastructure Deep Dive and The Network Impact of NVMe over Fabrics (NVMe-oF).

Intricate AWS IPv6 Direct Connect Challenges

In his Where AWS IPv6 networking fails blog post, Jason Lavoie documents an intricate consequence of 2-pizza-teams not talking to one another: it’s really hard to get IPv6 in AWS VPC working with Transit Gateway and Direct Connect in large-scale multi-account environment due to the way IPv6 prefixes are propagated from VPCs to Direct Connect Gateway.

It’s one of those IPv6-only little details that you could never spot before stumbling on it in a real-life deployment… and to make it worse, it works well in IPv4 if you did proper address planning (which you can’t in IPv6).

Intricate AWS IPv6 Direct Connect Challenges

In his Where AWS IPv6 networking fails blog post, Jason Lavoie documents an intricate consequence of 2-pizza-teams not talking to one another: it’s really hard to get IPv6 in AWS VPC working with Transit Gateway and Direct Connect in large-scale multi-account environment due to the way IPv6 prefixes are propagated from VPCs to Direct Connect Gateway.

It’s one of those IPv6-only little details that you could never spot before stumbling on it in a real-life deployment… and to make it worse, it works well in IPv4 if you did proper address planning (which you can’t in IPv6).

Worth Reading: The Lost Designer

Scott Berkun published another interesting article: The Lost Designer. As always, replace designer with networking engineer and enjoy.

Worth Reading: The Lost Designer

Scott Berkun published another interesting article: The Lost Designer. As always, replace designer with networking engineer and enjoy.

Lessons Learned: Technology Still Matters

In June 2020, a friend of mine asked me to do a short presentation on lessons learned during my 35 years of being a networking engineer. It went reasonably well, so I decided to turn it into a webinar, starting with regardless of what the disruptive marketers tell you, technology still matters.

Lessons Learned: Technology Still Matters

In June 2020, a friend asked me to do a short presentation on lessons learned during my 35 years as a networking engineer. It went reasonably well, so I decided to turn it into a webinar, starting with regardless of what the disruptive marketers tell you, technology still matters.

Unnumbered Ethernet Interfaces, DHCP Edition

Last week we explored the basics of unnumbered IPv4 Ethernet interfaces, and how you could use them to save IPv4 address space in routed access networks. I also mentioned that you could simplify the head-end router configuration if you’re using DHCP instead of per-host static routes.

Obviously you’d need a smart DHCP server/relay implementation to make this work. Simplistic local DHCP server would allocate an IP address to a client requesting one, send a response and move on. Likewise, a DHCP relay would forward a DHCP request to a remote DHCP server (adding enough information to allow the DHCP server to select the desired DHCP pool) and forward its response to the client.

Unnumbered Ethernet Interfaces, DHCP Edition

Last week we explored the basics of unnumbered IPv4 Ethernet interfaces, and how you could use them to save IPv4 address space in routed access networks. I also mentioned that you could simplify the head-end router configuration if you’re using DHCP instead of per-host static routes.

Obviously you’d need a smart DHCP server/relay implementation to make this work. Simplistic local DHCP server would allocate an IP address to a client requesting one, send a response and move on. Likewise, a DHCP relay would forward a DHCP request to a remote DHCP server (adding enough information to allow the DHCP server to select the desired DHCP pool) and forward its response to the client.

Real-Life Network-as-a-Graph Examples

After reading the Everything Is a Graph blog post, Vadim Semenov sent me a long list of real-life examples (slightly edited):

I work in a big enterprise and in order to understand a real packet path across multiple offices via routers and firewalls (when mtr or traceroute don’t work – they do not show firewalls), I made OSPF network visualization based on LSDB output. The idea is quite simple – save information about LSA1 and LSA2 (LSA5 optionally) and that will be enough in order to build a graph (use show ip ospf database router/network on Cisco devices).

Real-Life Network-as-a-Graph Examples

After reading the Everything Is a Graph blog post, Vadim Semenov sent me a long list of real-life examples (slightly edited):

I work in a big enterprise and in order to understand a real packet path across multiple offices via routers and firewalls (when mtr or traceroute don’t work – they do not show firewalls), I made OSPF network visualization based on LSDB output. The idea is quite simple – save information about LSA1 and LSA2 (LSA5 optionally) and that will be enough in order to build a graph (use show ip ospf database router/network on Cisco devices).

Unequal-Cost Multipath with BGP DMZ Link Bandwidth

In the previous blog post in this series, I described why it’s (almost) impossible to implement unequal-cost multipathing for anycast services (multiple servers advertising the same IP address or range) with OSPF. Now let’s see how easy it is to solve the same challenge with BGP DMZ Link Bandwidth attribute.

I didn’t want to listen to the fan noise generated by my measly Intel NUC when simulating a full leaf-and-spine fabric, so I decided to implement a slightly smaller network:

Unequal-Cost Multipath with BGP DMZ Link Bandwidth

In the previous blog post in this series, I described why it’s (almost) impossible to implement unequal-cost multipathing for anycast services (multiple servers advertising the same IP address or range) with OSPF. Now let’s see how easy it is to solve the same challenge with BGP DMZ Link Bandwidth attribute.

I didn’t want to listen to the fan noise generated by my measly Intel NUC when simulating a full leaf-and-spine fabric, so I decided to implement a slightly smaller network:

Feedback: Azure Networking

When I started developing AWS- and Azure Networking webinars, I wondered whether they would make sense – after all, you can easily find tons of training offerings focused on public cloud services.

However, it looks like most of those materials focus on developers (no wonder – they are the most significant audience), with little thought being given to the needs of network engineers… at least according to the feedback left by one of ipSpace.net subscribers.

Feedback: Azure Networking

When I started developing AWS- and Azure Networking webinars, I wondered whether they would make sense – after all, you can easily find tons of training offerings focused on public cloud services.

However, it looks like most of those materials focus on developers (no wonder – they are the most significant audience), with little thought being given to the needs of network engineers… at least according to the feedback left by one of ipSpace.net subscribers.

Worth Reading: The Neuroscience of Busyness

In the Neuroscience of Busyness article, Cal Newport describes an interesting phenomenon: when solving problems, we tend to add components instead of removing them.

If that doesn’t describe a typical network (or protocol) design, I don’t know what does. At least now we have a scientific basis to justify our behavior ;)

Worth Reading: The Neuroscience of Busyness

In the Neuroscience of Busyness article, Cal Newport describes an interesting phenomenon: when solving problems, we tend to add components instead of removing them.

If that doesn’t describe a typical network (or protocol) design, I don’t know what does. At least now we have a scientific basis to justify our behavior ;)

Worth Reading: Switching to IP fabrics

Namex, an Italian IXP, decided to replace their existing peering fabric with a fully automated leaf-and-spine fabric using VXLAN and EVPN running on Cumulus Linux.

They documented the design, deployment process, and automation scripts they developed in an extensive blog post that’s well worth reading. Enjoy ;)

Worth Reading: Switching to IP fabrics

Namex, an Italian IXP, decided to replace their existing peering fabric with a fully automated leaf-and-spine fabric using VXLAN and EVPN running on Cumulus Linux.

They documented the design, deployment process, and automation scripts they developed in an extensive blog post that’s well worth reading. Enjoy ;)