From 9b4595f744253f8a0d13d772131dc9851c9d32b2 Mon Sep 17 00:00:00 2001 From: Jeremy Stretch Date: Wed, 18 Jan 2017 10:50:04 -0500 Subject: [PATCH] Updated Frequently Asked Questions (markdown) --- Frequently-Asked-Questions.md | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/Frequently-Asked-Questions.md b/Frequently-Asked-Questions.md index b6d1a36..b2e4277 100644 --- a/Frequently-Asked-Questions.md +++ b/Frequently-Asked-Questions.md @@ -30,4 +30,12 @@ In keeping with its core design philosophy of directly modeling the real world, Omitting the mask from the IP address model would require us to make dangerous inferences about each IP address. For example, if you are given only the IP address 192.0.2.123, you cannot determine its network without additional information. You could look for its most-specific parent prefix: let's assume 192.0.2.0/24 has been created. But that doesn't necessarily indicate that our IP has a /24 mask. That /24 might be a smaller container used for administrative organization inside a larger parent, or there might be a more-specific /25 or /26 prefix missing from NetBox. Or it could be a loopback IP that should have a /32 mask. -Treating an IP address and its subnet mask as an atomic unit ensures a much greater degree of efficiency and accuracy. \ No newline at end of file +Treating an IP address and its subnet mask as an atomic unit ensures a much greater degree of efficiency and accuracy. + +# Why Can't I Connect a Virtual Circuit to an Interface? + +It's important to understand the difference between physical and virtual circuits. Suppose you have five sites arranged in a hub-and-spoke topology. The hub site has a point-to-point virtual circuit to each of its spoke sites; spoke-to-spoke traffic must pass through the hub. The virtual circuits are configured as 802.1Q-tagged subinterfaces on the hub site's router. + +In this scenario, there are five **physical** circuits: One to each of the five sites from the provider. These five circuits carry traffic to support an overlay comprising four **virtual circuits** (one to each spoke site from the hub). A physical circuit is responsible for the physical transmission of a signal from one point to another, whereas a virtual circuit is a purely logical construct. + +NetBox models only physical circuits, which can be terminated to physical interfaces on devices. While the ability to model virtual circuits would certainly be useful, it is impractical to account for the myriad technologies which might be used to establish a topology. \ No newline at end of file