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Worth Reading: VXLAN Drops Large Packets

Ian Nightingale published an interesting story of connectivity problems he had in a VXLAN-based campus network. TL&DR: it’s always the MTU (unless it’s DNS or BGP).

The really fun part: even though large L2 segments might have magical properties (according to vendor fluff), there’s no host-to-network communication in transparent bridging, so there’s absolutely no way that the ingress VTEP could tell the host that the packet is too big. In a layer-3 network you have at least a fighting chance…

For more details, watch the Switching, Routing and Bridging part of How Networks Really Work webinar (most of it available with Free Subscription).

Worth Reading: VXLAN Drops Large Packets

Ian Nightingale published an interesting story of connectivity problems he had in a VXLAN-based campus network. TL&DR: it’s always the MTU (unless it’s DNS or BGP).

The really fun part: even though large L2 segments might have magical properties (according to vendor fluff), there’s no host-to-network communication in transparent bridging, so there’s absolutely no way that the ingress VTEP could tell the host that the packet is too big. In a layer-3 network you have at least a fighting chance…

For more details, watch the Switching, Routing and Bridging part of How Networks Really Work webinar (most of it available with Free Subscription).

More Arista EOS BGP Route Reflector Woes

Most BGP implementations I’ve worked with split the neighbor BGP configuration into two parts:

  • Global configuration that creates the transport session
  • Address family configuration that activates the address family across a configured transport session, and changes the parameters that affect BGP updates

AS numbers, source interfaces, peer IPv4/IPv6 addresses, and passwords clearly belong to the global neighbor configuration.

More Arista EOS BGP Route Reflector Woes

Most BGP implementations I’ve worked with split the neighbor BGP configuration into two parts:

  • Global configuration that creates the transport session
  • Address family configuration that activates the address family across a configured transport session and changes the parameters that affect BGP updates

AS numbers, source interfaces, peer IPv4/IPv6 addresses, and passwords clearly belong to the global neighbor configuration.

Starting with EOS release 4.29.0F, you can configure the neighbor next-hop-self option within IPv4 and IPv6 address families. Great job! Hopefully, we can consider this blog post a historical curiosity.

EVPN/MPLS Bridging Forwarding Model

Most networking engineers immediately think about VXLAN and data center switches when they hear about EVPN. While that’s the most hyped use case, EVPN standardization started in 2012 as a layer-2 VPN solution on top of MPLS transport trying to merge the best of VPLS and MPLS/VPN worlds.

If you want to understand how any technology works, and what its quirks are, you have to know how it was designed to be used. In this blog post we’ll start that journey exploring the basics of EVPN used in a simple MLPS network with three PE-routers:

Lab topology

Lab topology

EVPN/MPLS Bridging Forwarding Model

Most networking engineers immediately think about VXLAN and data center switches when they hear about EVPN. While that’s the most hyped use case, EVPN standardization started in 2012 as a layer-2 VPN solution on top of MPLS transport trying to merge the best of VPLS and MPLS/VPN worlds.

If you want to understand how any technology works, and what its quirks are, you have to know how it was designed to be used. In this blog post we’ll start that journey exploring the basics of EVPN used in a simple MLPS network with three PE-routers:

Lab topology

Lab topology

Worth Reading: QUIC Is Not a TCP Replacement

Bruce Davie makes an excellent point in his QUIC Is Not a TCP Replacement article – QUIC not a next-generation TCP, it’s a reliable RPC transport protocol.

What Bruce forgot to mention is that we had a production-grade RPC transport protocol for years – SCTP (Stream Control Transmission Protocol) – but it had two shortcomings:

Worth Reading: QUIC Is Not a TCP Replacement

Bruce Davie makes an excellent point in his QUIC Is Not a TCP Replacement article – QUIC not a next-generation TCP, it’s a reliable RPC transport protocol.

What Bruce forgot to mention is that we had a production-grade RPC transport protocol for years – SCTP (Stream Control Transmission Protocol) – but it had two shortcomings:

Worth Reading: EVPN/VXLAN with FRR on Linux Hosts

Jeroen Van Bemmel created another interesting netlab topology: EVPN/VXLAN between SR Linux fabric and FRR on Linux hosts based on his work implementing VRFs, VXLAN, and EVPN on FRR in netlab release 1.3.1.

Bonus point: he also described how to do multi-vendor interoperability testing with netlab.

If only he wouldn’t be publishing his articles on a platform that’s almost as user-data-craving as Google.

Worth Reading: EVPN/VXLAN with FRR on Linux Hosts

Jeroen Van Bemmel created another interesting netlab topology: EVPN/VXLAN between SR Linux fabric and FRR on Linux hosts based on his work implementing VRFs, VXLAN, and EVPN on FRR in netlab release 1.3.1.

Bonus point: he also described how to do multi-vendor interoperability testing with netlab.

If only he wouldn’t be publishing his articles on a platform that’s almost as user-data-craving as Google.

Video: Kubernetes Services Types

Kubernetes services are like networking standards: there are so many to choose from. In his brief introduction to Kubernetes service types, Stuart Charlton listed six of them, and I’m positive there are more. That’s what you get when you’re trying to reinvent every network load balancing method known to mankind ;)

Parts of Kubernetes Networking Deep Dive webinar (including this video) are available with Free ipSpace.net Subscription.

Video: Kubernetes Services Types

Kubernetes services are like networking standards: there are so many to choose from. In his brief introduction to Kubernetes service types, Stuart Charlton listed six of them, and I’m positive there are more. That’s what you get when you’re trying to reinvent every network load balancing method known to mankind ;)

Parts of Kubernetes Networking Deep Dive webinar (including this video) are available with Free ipSpace.net Subscription.

Cumulus Linux Network Command Line Utility (NCLU)

While ranting about Linux data plane configuration, I mentioned an interesting solution: Cumulus Linux Network Command Line Utility (NCLU), an attempt to make Linux networking more palatable to more traditional networking engineers.

NCLU is a simple wrapper around ifupdown2 and frr packages. You can execute net add and net del commands to set or remove configuration parameters1, and NCLU translates those commands into changes to corresponding configuration files.

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