Dynamic Tunneling Configuration for Network with Uni-Directional Link

ICCC99 – 15/09/1999

Mikiyo NISHIDA / KEIO Univ.

Hiroyuki KUSUMOTO / KEIO Univ.

Jun MURAI / KEIO Univ.

General Description

• Introdunction– Characteristics of Uni-Directional Link

• Current Problems of Uni-Directional Link• Scheme

– Dynamic Tunneling Configuration

• Design– Message based mechanism

• Implementation– Implement our mechanism

• Conclusion

Introduction(1) UDL

• Uni Directional Link– One-way (most case:Multiple Access)data link

• Satellite

• Cable TV

Introduction(2) Network with UDL

• Network with UDL & BDL (Bi-Directional Link)– We assume UDL

network in the Internet has UDL and another BDL accessibility

Introduction(3)Tunneling Techniques

• For Simulating link solution– tunneling

• Current Tunneling Scheme– Static Configuration– Few Scalability– Too much management cost

We propose‘ Dynamic Tunnel Configuration Scheme’

Current Problems(1)Routing in network with UDL

• Current Internet Routing Protocol– Based on Link Bi-directonality

• Approaches for using UDL network– Modify Routing Protocol– Provide Bi-Directional accessibility for UDL vi

rtually

Current Problems(2) Data-link address resolution in UDL

• Multiple access data-link requires data-link address resolution– Ethernet use ARP protocol

Current Problems(3)IP Address Assignment in UDL

• UDL has a lot of receivers

• IP address is limited resource

Current Problems - Overall

• Routing Problems

• Data-link address resolution

• IP Address Assignment

Dynamic Tunneling Scheme(1)

• We propose Dynamic Tunneling Configuration Scheme– Provide virtual return path of UDL

automatically– Provide mechanism of data-link address

resolution on UDL– Provide mechanism of IP address dynamic

assignment

Dynamic Tunneling Scheme(2)

• Message based mechanism– Exchange messages over UDL and BDL– UDL Keepalive– Setup/Shutdown tunnel– Data-link address resolution– IP Address Automatically Assignment

Design(1) General Description

Design(2) Messages

• Notify Message (via UDL)– Sender to Receiver

• HELLO message– Notify Sender Information

– Applied UDL Keep Alive

Design(3) Messages

• Control Message (via BDL)– Exchange each other

• REQUEST Message (Receiver to Sender)– Notify Receiver beginning to use UDL– Request Tunnel Setup, IP Address Assign

• REPLY Message (Sender to Receiver)– Reply for Receiver’s message

• REFRESH/RELEASE Message (Receiver to Sender)– Notify Receiver uses UDL continuously / terminate using

UDL

Design(4) Modules

• Virtual Link Module– Manipulate tunneling packets

• Control Module– Manipulate messages– Set/Release tunnel– Set/Release interface’s IP address– Maintain IP/DL address

Design(5) Operating cycle

Implementation(1)

• Target Architecture:– FreeBSD 2.2.1-Release

• Modified data-link routine in Unix Kernel• UDL: Use Ethernet (Modified Output Routine)

• BDL: Use Ethernet

• Virtual Link Module is implemented in Unix Kernel

• Control Module is implemented as user process application

Implementation(2) Virtual Link Module

• Total of 120 lines:– if_ethersubr.c

• ether_input(), ether_output()

• Add encapsulation/decapsulation function

– if.c• if_ioctl()

• Add manipulating tunnel information function

Implementation(3)Control module

• Code size– Total of 1450 lines / at Receiver– Total of 1436 lines / at Sender

• Implement as user process application

• Send and receive messages via UDP

• Maintenance DL/IP address table

Conclusion

• Describe current problems of network with unidirectional link

• Propose Dynamic Tunnel Configuration Scheme

• Implement our proposed mechanism

• Present usability of this scheme

Future Work

• Test many types of routing protocols

• Improve performance and scalability