Layered Protocols in Click

jinkscabbageΔίκτυα και Επικοινωνίες

23 Οκτ 2013 (πριν από 3 χρόνια και 8 μήνες)

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ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Layered Protocols in Click
Implementation of Layered Protocols with Click Modular Router
Bart Braem Michael Voorhaen
University of Antwerp
IBBT - PATS Research Group
October 2011
Bart Braem,Michael Voorhaen
Layered Protocols in Click
1/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Click in ISO/OSI Reference Model
Bart Braem,Michael Voorhaen
Layered Protocols in Click
2/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
IP Router
Bart Braem,Michael Voorhaen
Layered Protocols in Click
3/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Input Path
Handles ARP
Classifies
ARP Requests
ARP Replies
Data
Bart Braem,Michael Voorhaen
Layered Protocols in Click
4/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Routing Path
Remove Ethernet Header
Check if the IP header is
correct
Routes the packet
local
forwarding path
Bart Braem,Michael Voorhaen
Layered Protocols in Click
5/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Output Path
Check if the packet should
be forwarded
If not send an ICMP error
Routes the packet
GW
TTL exceeded
Fragmentation
else forward the packet
via ARPQuerier
Bart Braem,Michael Voorhaen
Layered Protocols in Click
6/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
IP Router
Bart Braem,Michael Voorhaen
Layered Protocols in Click
7/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Layered Moded in Click
"With great power comes great responsibility."
Click receives raw ethernet frames from Layer 2 and handles all
the processing up until it is handed to the higher layers.
Click can also handle Transport layer headers such as
intercepting UDP and TCP packets making it possible to
implement daemons inside Click.
The user is in charge of respecting the layered model,not
Click.
Try to adhere to the ISO/OSI reference layer as much as possible.
This makes sure that the packets you handle are what you expect.
Bart Braem,Michael Voorhaen
Layered Protocols in Click
8/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Following the Layered Model
e.g.What if you need to capture
UDP packets on port 7.
Capturing them after the
Routing Path decides the
packet has reached its
destination.
This ensures that you
capture valid IP packets with
the correct destination.
Bart Braem,Michael Voorhaen
Layered Protocols in Click
9/10
ISO/OSI Reference Model
IP Router
Respecting the Layered Model
Breaking the Layered Model
If you would capture the packet di-
rectly from the input (interface):
You could be processing the
wrong packet the wrong way
(e.g.treat an ARP message
as UDP).
You would have to add all
these checks yourself in Click
or even worse inside your
own element.
Bart Braem,Michael Voorhaen
Layered Protocols in Click
10/10