diff --git a/selected/http_to_phy.md b/selected/http_to_phy.md
index 618b3fa..191c246 100644
--- a/selected/http_to_phy.md
+++ b/selected/http_to_phy.md
@@ -161,10 +161,11 @@ Link speed negotiation
 
 (intel) NUC with two (usb) NICs -- VMs that would tag traffic with VLAN.
 Ethernet packet tagged with VLAN 1, 
-
+```
 | 1 1 1 1 1 1 1 2 | | 2i 2o |
 |               2 | |  NUC  |
 |               2 | |       |
+```
 
 layer 2 ethernet -- hamachi / layer 3 ip -- openvpn
 
@@ -177,7 +178,7 @@ Routers are layer 3
 Home "router" is a router / switch combo
 
 Network Topology -- this is mostly outside my wheelhouse; infiniband/optics?
-
+```
 "crossover cable"
 A            B
 TX ---\/--- TX
@@ -187,17 +188,19 @@ RX ---/\--- RX
 A            B
 TX -------- TX
 RX -------- RX
-
+```
 
 Switch maintains an ethernet routing table, uses mac addresses to determine which ports need to be routed to other ports
 
 TTL -- preventing packets from hopping forever on layer 3 connections, ICMP is a totally separate thing
 ICMP -- https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
 
+```
 SEND CHEESEBURGER TO GOOGLE
 A -> HR -> ISP -> | | | | -> GOOGLE
 subnet 192.168.1.X
 HR -> ISP | DESTINATION UNREACHABLE {ICMP 3} | TIME EXCEEDED {ICMP 11} TTL Expires
+```
 Blocking ICMP is messy, be careful!
 
 https://en.wikipedia.org/wiki/Black_hole_(networking)