Worth Reading: Some Thoughts on Digital Twins

I encountered several articles explaining the challenges of simulating your network in a virtual lab in the last few months, including:

• Some thoughts on digital twins by Jeff McLaughlin
• Network Simulation is hard – Part 1, Part 2 – by Pete Crocker
• Twenty-five open-source network emulators and simulators you can use in 2023 by Brian Linkletter

Enjoy!

Worth Reading: Introduction of EVPN at DE-CIX

Numerous Internet Exchange Points (IXP) started using VXLAN years ago to replace tradition layer-2 fabrics with routed networks. Many of them tried to avoid the complexities of EVPN and used VXLAN with statically-configured (and hopefully automated) ingress replication.

A few went a step further and decided to deploy EVPN, primarily to deploy Proxy ARP functionality on EVPN switches and reduce the ARP/ND traffic. Thomas King from DE-CIX described their experience on APNIC blog – well worth reading if you’re interested in layer-2 fabrics.

Worth Reading: Introduction of EVPN at DE-CIX

Numerous Internet Exchange Points (IXP) started using VXLAN years ago to replace tradition layer-2 fabrics with routed networks. Many of them tried to avoid the complexities of EVPN and used VXLAN with statically-configured (and hopefully automated) ingress replication.

A few went a step further and decided to deploy EVPN, primarily to deploy Proxy ARP functionality on EVPN switches and reduce the ARP/ND traffic. Thomas King from DE-CIX described their experience on APNIC blog – well worth reading if you’re interested in layer-2 fabrics.

Video: What Is Software-Defined Data Center

A few years ago, I was asked to deliver a What Is SDDC presentation that later became a webinar. I forgot about that webinar until I received feedback from one of the viewers a week ago:

If you like to learn from the teachers with the “straight to the point” approach and complement the theory with many “real-life” scenarios, then ipSpace.net is the right place for you.

I haven’t realized people still find that webinar useful, so let’s make it viewable without registration, starting with What Problem Are We Trying to Solve and What Is SDDC.

Video: What Is Software-Defined Data Center

A few years ago, I was asked to deliver a What Is SDDC presentation that later became a webinar. I forgot about that webinar until I received feedback from one of the viewers a week ago:

If you like to learn from the teachers with the “straight to the point” approach and complement the theory with many “real-life” scenarios, then ipSpace.net is the right place for you.

I haven’t realized people still find that webinar useful, so let’s make it viewable without registration, starting with What Problem Are We Trying to Solve and What Is SDDC.

netlab 1.6.2: More Reporting Goodies

netlab release 1.6.2 improved reporting capabilities:

• BGP reports and IP addressing reports are fully IPv6-aware
• Some columns in BGP reports are optional to reduce the width of text reports
• You can filter the reports you’re interested in when using netlab show reports command
• Reports relying on ipaddr Ansible filter display warnings (instead of crashing) if you don’t have Ansible installed.

In other news:

• Stefano Sasso added support for ArubaOS-CX running within containerlab
• You can use inter-VRF route leaking with Cumulus Linux or FRR

netlab 1.6.2: More Reporting Goodies

netlab release 1.6.2 improved reporting capabilities:

• BGP reports and IP addressing reports are fully IPv6-aware
• Some columns in BGP reports are optional to reduce the width of text reports
• You can filter the reports you’re interested in when using netlab show reports command
• Reports relying on ipaddr Ansible filter display warnings (instead of crashing) if you don’t have Ansible installed.

In other news:

• Stefano Sasso added support for ArubaOS-CX running within containerlab
• You can use inter-VRF route leaking with Cumulus Linux or FRR

BGP Labs: Route Aggregation

In the BGP Route Aggregation lab you can practice:

• OSPF-to-BGP route redistribution
• BGP route aggregation
• Suppression of more-specific prefixes in the BGP table
• Prefix-based filtering of outbound BGP updates

Note: if you want to keep things simple, run BGP labs with netlab (other options).

BGP Labs: Route Aggregation

In the BGP Route Aggregation lab you can practice:

• OSPF-to-BGP route redistribution
• BGP route aggregation
• Suppression of more-specific prefixes in the BGP table
• Prefix-based filtering of outbound BGP updates

What Is Ultra Ethernet All About?

If you’re monitoring the industry press (or other usual hype factories), you might have heard about Ultra Ethernet, a dazzling new technology that will be developed by the Ultra Ethernet Consortium¹. What is it and does it matter to you (TL&DR: probably not²)?

As always, let’s start with What Problem Are We Solving?

What Is Ultra Ethernet All About?

If you’re monitoring the industry press (or other usual hype factories), you might have heard about Ultra Ethernet, a dazzling new technology that will be developed by the Ultra Ethernet Consortium¹. What is it, and does it matter to you (TL&DR: probably not²)?

As always, let’s start with What Problem Are We Solving?

BGP Session Security: Be Very Skeptical

A while ago I explained how Generalized TTL Security Mechanism could be used to prevent denial-of-service attacks on routers running EBGP. Considering the results published in Analyzing the Security of BGP Message Parsing presentation from DEFCON 31 I started wondering how well GTSM implementations work.

TL&DR summary:

BGP Session Security: Be Very Skeptical

A while ago I explained how Generalized TTL Security Mechanism could be used to prevent denial-of-service attacks on routers running EBGP. Considering the results published in Analyzing the Security of BGP Message Parsing presentation from DEFCON 31 I started wondering how well GTSM implementations work.

TL&DR summary:

Worth Reading: Flow Distribution Across ECMP Paths

Dip Singh wrote another interesting article describing how ECMP load balancing implementations work behind the scenes. Absolutely worth reading.

Worth Reading: Flow Distribution Across ECMP Paths

Dip Singh wrote another interesting article describing how ECMP load balancing implementations work behind the scenes. Absolutely worth reading.

Worth Reading: Single-Port LAGs

Lindsay Hill described an excellent idea: all ports on your switches routers should be in link aggregation groups even when you have a single port in a group. That approach allows you to:

• Upgrade the link speed without changing any layer-3 configuration
• Do link maintenance without causing a routing protocol flap

It also proves RFC 1925 rule 6a, but then I guess we’re already used to that ;)

Worth Reading: Single-Port LAGs

Lindsay Hill described an excellent idea: all ports on your switches routers should be in link aggregation groups even when you have a single port in a group. That approach allows you to:

• Upgrade the link speed without changing any layer-3 configuration
• Do link maintenance without causing a routing protocol flap

It also proves RFC 1925 rule 6a, but then I guess we’re already used to that ;)

How GitHub Saved My Day

I always tell networking engineers who aspire to be more than VLAN-munging CLI jockeys to get fluent with Git. I should also be telling them that while doing local version control is the right thing to do, you should always have backups (in this case, a remote repository).

I’m eating my own dog food¹ – I’m using a half dozen Git repositories in ipSpace.net production². If they break, my blog stops working, and I cannot publish new documents³.

Now for a fun fact: Git is not transactionally consistent.

How GitHub Saved My Day

I always tell networking engineers who aspire to be more than VLAN-munging CLI jockeys to get fluent with Git. I should also be telling them that while doing local version control is the right thing to do, you should always have backups (in this case, a remote repository).

I’m eating my own dog food¹ – I’m using a half dozen Git repositories in ipSpace.net production². If they break, my blog stops working, and I cannot publish new documents³.

Now for a fun fact: Git is not transactionally consistent.

BGP Labs: Use BFD to Speed Up Convergence

In the next BGP labs exercise you can practice tweaking BGP timers and using BFD to speed up BGP convergence.

I would strongly recommend using netlab to run BGP labs, but if you insist you can use any system you like including physical hardware.