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.

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.

Why Do We Need Source IP Addresses in IP Headers?

After discussing names, addresses and routes, and the various addresses we might need in a networking stack, we’re ready to tackle an interesting comment made by a Twitter user as a reply to my Why Is Source Address Validation Still a Problem? blog post:

Maybe the question we should be asking is why there is a source address in the packet header at all.

Most consumers of network services expect a two-way communication – you send some stuff to another node providing an interesting service, and you usually expect to get some stuff back. So far so good. Now for the fun part: how does the server know where to send the stuff back to? There are two possible answers¹:

Why Do We Need Source IP Addresses in IP Headers?

After discussing names, addresses and routes, and the various addresses we might need in a networking stack, we’re ready to tackle an interesting comment made by a Twitter user as a reply to my Why Is Source Address Validation Still a Problem? blog post:

Maybe the question we should be asking is why there is a source address in the packet header at all.

Most consumers of network services expect a two-way communication – you send some stuff to another node providing an interesting service, and you usually expect to get some stuff back. So far so good. Now for the fun part: how does the server know where to send the stuff back to? There are two possible answers¹:

Does EVPN/VXLAN over SD-WAN Make Sense?

It looks like we might be seeing VXLAN-over-SDWAN deployments in the wild. Here’s the “why that makes sense” argument I received from a participant of the ipSpace.net Design Clinic in which I wasn’t exactly enthusiastic about the idea.

Also, the EVPN-over-WAN idea is not hypothetical since EVPN+VXLAN is now the easiest way to build L3VPN with data center switches that don’t support MPLS LDP. Folks with no interest in EVPN’s L2 features are still using it for L3VPN.

Let’s unravel this scenario a bit: