good lord theres so much missing in this commit

cst311/lec/lec11.md

@@ -25,5 +25,5 @@ Say we have two competing sessions:
 
 Certain types of applications won't be be rate limited by TCP fairness.
 Streaming video for instance won't since we just want to _throw_ data across as much as possible.
-That being said we do have to tolerate loss since UDP doesn't account for data loss on the line in any significant manner.
+This also means we have to account for loss and tolerate it when it does happen because UDP doesn't account for loss anyway.
 

cst311/lec/lec12.md

@@ -0,0 +1,53 @@
+# lec12
+
+Networkk Layer
+
+Here instead of datagrams, or segments, we are referring to chunks of data as _datagrams_.
+We concern ourselves with _host to host communication_.
+There are two major function to worry about:
+
+* forwarding
+	* getting from an input to an output
+* routing
+	* concerned with 
+
+## Virtual Circuits
+
+_THIS SECTION IS BAREBONES_ 
+
+Datagram Service: network provides network-layer _connectionless_ service.
+
+Virtual Circuit: network provides network-layer _connection_ service.
+
+### Setup a connection
+
+Virtual Connections: before two end hosts start sending data to each other both must determine over which route they will communicate with.
+This means that we have to get routers between hosts involved with this initial setup.
+
+When the routers get involved they put an incoming vc number on an incoming bus, and an outgoing vc number on an outgoing bus.
+These entries are stored in the routers _forwarding table_.
+
+## VC Implementation
+
+1. Path from source to destination
+2. VC numbers one number for each link
+3. entries in forwarding table
+
+### Forwarding Table
+
+__pls clarify section__
+
+Each router has a forwarding table which allows for entries regarding data about it's incoming/outgoing buses.
+
+Router has has incoming/outgoing interface on these lines we see that datagram has a vc# when its incoming to the router.
+Upon exit we know that each vc# from the incoming interface corresponds to a vc# on some outgoing interface.
+
+## IP Addresses & Datagram forwarding tables
+
+> What is an ip address?
+
+Think of an adress of a variable in memory.
+Instead of a variable we have an end host.
+Instead of an address memory we have an address in some network.
+
+Usually we'll write a destination address in the header of a datagram so that we know where the data is meant to go.