Difference between revisions of "Manual:Packet Flow"

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(Basic Concepts)
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===Basic Concepts===
 
===Basic Concepts===
  
[[Image:Input_interface.jpg|Input Interface|100px]] -  
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[[Image:Input_interface.jpg|Input Interface|100px]] - starting point in packets way thought the router facilities. It does not matter what interface (physical or virtual) packet is received it will start its way from here.
  
[[Image:output_interface.jpg|Output Interface|100px]]
+
[[Image:output_interface.jpg|Output Interface|100px]] - last point in packets way thought the router facilities. Just before the packet is actually sent out.
  
[[Image:local_process-_in.jpg|Filter Output|100px]]
+
[[Image:local_process-_in.jpg|Filter Output|100px]] - last point in packets way '''to''' router itself, after this packet is discarded
  
[[Image:local_process-_out.jpg|Filter Output|100px]]
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[[Image:local_process-_out.jpg|Filter Output|100px]] - starting point for packets generated by router itself
 
 
[[Image:hotspot_in.jpg|Hotspot In|100px]]
 
 
 
[[Image:Hotspot_out.jpg|Hotspot Out|100px]]
 
  
 
===Configurable Facilities===
 
===Configurable Facilities===

Revision as of 17:15, 27 November 2008

MikroTik RouterOS is designed to be easy to operate in various aspects of network configuration. Therefore creating limitation for individual IP or natting internal clients to a public address or Hotspot configuration can be done without the knowledge about how the packets are processed in the router - you just go to corresponding menu and create necessary configuration.

However more complicated tasks, such as traffic prioritization, routing policies, where it is necessary to utilize more than one RouterOS facility, requires knowledge: How these facilities work together? What happens when and why?

To address these questions we created a packet flow diagram.

Diagram

As it was impossible to get everything in one diagram, Packet flow diagram for Mikrotik RouterOS v3.x was created in 2 parts:

  • Bridging or Layer-2 (MAC) where Routing part is simplified to one "Layer-3" box
  • Routing or Layer-3 (IP) where Bridging part is simplified to one "Bridging" box


Packet Flow in Layer-2



Packet Flow in Layer-3



Analysis

Basic Concepts

Input Interface - starting point in packets way thought the router facilities. It does not matter what interface (physical or virtual) packet is received it will start its way from here.

Output Interface - last point in packets way thought the router facilities. Just before the packet is actually sent out.

Filter Output - last point in packets way to router itself, after this packet is discarded

Filter Output - starting point for packets generated by router itself

Configurable Facilities

Each and every facilities in this section corresponds with one particular menu in RouterOS. Users are able to access those menu and configure these facilities directly


Connection Tracking - /ip firewall connection tracking

Filter Input Filter Forward Filter Output - /ip firewall filter

Source NAT Destination NAT - /ip firewall nat

Mangle Prerouting Mangle Input Mangle Forward Mangle Output Mangle Postrouting - /ip firewall mangle

Global-in HTB Global-Out HTB Interface HTB - /queue simple and /queue tree

IPSec_Policy - /ip ipsec policy

Use IP Firewall - /interface bridge settings

Bridge Forward Bridge Input Bridge Output - /interface bridge filter

Bridge Destination NAT Bridge Source NAT - /interface bridge nat


Automated processes and desicions

Routing Adjustment

Accounting

TTL Adjustment

Bridge Decision

IPSec_Decryption

IPSec_Encryption

In-interface Bridge

Out-interface Bridge

Bridge Decision





Examples

Example1: Bridging with use-ip-firewall=yes

Example2: Routing - from Ethernet to Ethernet interface

Example3: Routing from one Bridge interface to another

Example4: IPsec encryption and sending to the peer

Example5: IPsec data receiving and decryption