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Update 'selected/http_to_phy.md'

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cloin 2022-05-28 04:01:42 +00:00
parent 0da41431f0
commit ae1cfcfb19
1 changed files with 6 additions and 3 deletions
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@ -161,10 +161,11 @@ Link speed negotiation
(intel) NUC with two (usb) NICs -- VMs that would tag traffic with VLAN. (intel) NUC with two (usb) NICs -- VMs that would tag traffic with VLAN.
Ethernet packet tagged with VLAN 1, Ethernet packet tagged with VLAN 1,
```
| 1 1 1 1 1 1 1 2 | | 2i 2o | | 1 1 1 1 1 1 1 2 | | 2i 2o |
| 2 | | NUC | | 2 | | NUC |
| 2 | | | | 2 | | |
```
layer 2 ethernet -- hamachi / layer 3 ip -- openvpn layer 2 ethernet -- hamachi / layer 3 ip -- openvpn
@ -177,7 +178,7 @@ Routers are layer 3
Home "router" is a router / switch combo Home "router" is a router / switch combo
Network Topology -- this is mostly outside my wheelhouse; infiniband/optics? Network Topology -- this is mostly outside my wheelhouse; infiniband/optics?
```
"crossover cable" "crossover cable"
A B A B
TX ---\/--- TX TX ---\/--- TX
@ -187,17 +188,19 @@ RX ---/\--- RX
A B A B
TX -------- TX TX -------- TX
RX -------- RX RX -------- RX
```
Switch maintains an ethernet routing table, uses mac addresses to determine which ports need to be routed to other ports 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 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 ICMP -- https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
```
SEND CHEESEBURGER TO GOOGLE SEND CHEESEBURGER TO GOOGLE
A -> HR -> ISP -> | | | | -> GOOGLE A -> HR -> ISP -> | | | | -> GOOGLE
subnet 192.168.1.X subnet 192.168.1.X
HR -> ISP | DESTINATION UNREACHABLE {ICMP 3} | TIME EXCEEDED {ICMP 11} TTL Expires HR -> ISP | DESTINATION UNREACHABLE {ICMP 3} | TIME EXCEEDED {ICMP 11} TTL Expires
```
Blocking ICMP is messy, be careful! Blocking ICMP is messy, be careful!
https://en.wikipedia.org/wiki/Black_hole_(networking) https://en.wikipedia.org/wiki/Black_hole_(networking)