The “should we use the same vendor for fabric spines and leaves?” discussion triggered the expected counterexamples. Here’s one:
I actually have worked with a few orgs that mix vendors at both spine and leaf layer. Can’t take names but they run fairly large streaming services. To me it seems like a play to avoid vendor lock-in, drive price points down and be in front of supply chain issues.
As always, one has to keep two things in mind:
One of my readers was building a private MPLS/VPN backbone and wondered whether they should use their public AS number or a private AS number for the backbone. Usually, it doesn’t matter; the deciding point was the way they want to connect to the public Internet:
We also plan to peer with multiple external ISPs to advertise our public IP space not directly from our PE routers but from dedicated Internet Routers, adding a firewall between our PEs and external Internet routers.
They could either run BGP between the PE routers, firewall, and WAN routers (see BGP as High-Availability Protocol for more details) or run BGP across a bump-in-the-wire firewall:
One of my readers was building a private MPLS/VPN backbone and wondered whether they should use their public AS number or a private AS number for the backbone. Usually, it doesn’t matter; the deciding point was the way they want to connect to the public Internet:
We also plan to peer with multiple external ISPs to advertise our public IP space not directly from our PE routers but from dedicated Internet Routers, adding a firewall between our PEs and external Internet routers.
They could either run BGP between the PE routers, firewall, and WAN routers (see BGP as High-Availability Protocol for more details) or run BGP across a bump-in-the-wire firewall:
Ultimately, every problem in the constantly evolving IT software stack becomes a database problem, which is why there are 418 different databases and datastores in the DB Engines rankings and there are really only a handful of commercially viable operating systems. …
The Cloud Outgrows Linux, And Sparks A New Operating System was written by Timothy Prickett Morgan at The Next Platform.
In the previous chapter, we discussed how a VTEP learns the local TS's MAC address and the process through which the MAC address is programmed into BGP tables. An example VTEP device was configured with a Layer 2 VLAN and an EVPN Instance without deploying a VRF Context or VLAN routing interface. This chapter introduces, at a theoretical level, how the VTEP device, besides the TS's MAC address, learns the TS's IP address information after we have configured the VRF Context and routing interface for our example VLAN.
Figure 1-3: MAC-VRF Tenant System’s IP Address Propagation.
I have divided Figure 1-3 into three sections. The section on the top left, Integrated Routing and Bridging - IRB illustrates the components required for intra-tenant routing and their interdependencies. By configuring a Virtual Routing and Forwarding Context (VRF Context), we create a closed routing environment with a per-tenant IP-VRF L3 Routing Information Base (L3RIB). Within the VRF Context, we define the Layer 3 Virtual Network Identifier (L3VNI) along with the Route Distinguisher (RD) and Route Target (RT) values. The RD of the VRF Context enables the use of overlapping IP addresses across different tenants. Based on the RT value of the VRF Context, Continue reading
In the Do We Still Need OSPF Areas and Summarization? I wrote this somewhat cryptic remark:
The routers advertising a summarized prefix should be connected by a path going exclusively through the part of the network with more specific prefixes. GRE tunnel also satisfies that criteria; the proof is left as an exercise for the reader.
One of my readers asked for a lengthier explanation, so here we go. Imagine a network with two areas doing inter-area summarization on /24 boundary:
In the Do We Still Need OSPF Areas and Summarization? I wrote this somewhat cryptic remark:
The routers advertising a summarized prefix should be connected by a path going exclusively through the part of the network with more specific prefixes. GRE tunnel also satisfies that criteria; the proof is left as an exercise for the reader.
One of my readers asked for a lengthier explanation, so here we go. Imagine a network with two areas doing inter-area summarization on /24 boundary:
With the reticle limit for chip manufacturing pretty much set in stone (pun intended) at 26 millimeters by 33 millimeters down to 2 nanometer transistor sizes with extreme ultraviolet lithography techniques and being cut in half to 26 millimeters by 16.5 millimeters for the High-NA extreme ultraviolet lithography needed to push below 2 nanometer transistor sizes, chiplets are inevitable and monolithic dies are absolutely going to become a thing of the past. …
HexaMesh: Chiplet Topologies Inspired By Nature was written by Timothy Prickett Morgan at The Next Platform.
If you grew up in the 80s watching movies like me, you’ll remember Wargames. I could spend hours lauding this movie but for the purpose of this post I want to call out the sequence at the beginning when the two airmen are trying to operate the nuclear missile launch computer. It requires the use of two keys, one each in the possession of one of the airmen. They must be inserted into two different locks located more than ten feet from each other. The reason is that launching the missile requires two people to agree to do something at the same time. The two key scene appears in a number of movies as a way to show that so much power needs to have controls.
However, one thing I wanted to talk about in this post is the notion that those controls need to be visible to be effective. The two key solution is pretty visible. You carry a key with you but you can also see the locks that are situated apart from each other. There is a bit of challenge in getting the keys into the locks and turning them simultaneously. That not only shows that the Continue reading