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Re: second draft agenda
At 22:01 97/04/04 +0200, Walid Dabbous wrote:
> b) the current proposed solutions ? (should we post them as I-Ds if there
> is an agreed solution?)
>
> b.1) VIPRE proposed I-D (on the tunneling approach) (from Aerospace)
> b.2) an I-D on the protocols modification approach (from INRIA)
> other?
I rewrote our approach as a I-D to say our approach more clearly.
I post it only to this mailing list.
izu / WIDE project
%%% %%%
Network Working Group Hidetaka Izumiyama
Internet-Draft Akihiro Tosaka
WIDE project
April 1996
Uni-directional Link Routing with IP tunneling
<draft-ietf-wide-udlr-vif-00.txt>
Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
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ftp.isi.edu (US West Coast).
Abstract
This document defines the idea to use unidirectional link(UDL) routing
without any modifications of current routing protocols.
Table of Contents
1.Term
Feed
Receiver
VIF
2.Design of VIF
3.Merits and demerits of this design
3.1.Merits
3.2.Demerits
4.Architecture of VIF
5.Behavior of VIF on Feed and Receiver
5.1.On Feed
5.2.On Receiver
6.Tunnels
7.Bibliography
1.Terms
Feed -
The host which send the packet to the uni-directional
link (UDL).
Receiver -
The host which receive the packet from the UDL. He
can not send packet to the UDL.
VIF(Virtual Interface) -
The interface which emulate a UDL as a BDL.
NIF(Normal Interface) -
The interface which is currently using Internet.
It handles BDL.
2.Design of VIF
Current routing protocols are designed
on the premise that a host creates a bi-directional link(BDL)
with a neighbor through one interface.
The Feed and Receiver are connected by one
uni-directional link(UDL)
and one BDL link describe below,
current routing protocols can use only one BDL link
(if1). Even if Feed can send the packet though
if0 , if0 never use.
UDL
------->------------------>-------
| |
|if0 |if0
+--------+ +--------+
| Feed | |Receiver|
+----+---+ +--------+
|if1 |if1
| |
===============BDL================
Fig-1 physical connection
UDL
------->------------------>-------
+--------+ +--------+
| Feed | |Receiver|
+----+---+ +--------+
|if1 |if1
| |
===============BDL================
Fig-2a logical connection for current routing protocols
(only use current technology)
We design the virtual interface(VIF) to emulate a UDL
as a BDL by using IP tunneling technology
on another BDL link. The packet from Receiver to if0
is encapsulated and send if1 to Feed. Feed receive
the encapsulated packet from if1, the packet is decapsulated
and go around if0 and receive as it come from if0.
So,current routing protocols can use if0 and if1.
BDL
==================================
| |
|if0(VIF) |if0(VIF)
+--------+ +--------+
| Feed | |Receiver|
+----+---+ +--------+
|if1 |if1
| |
===============BDL================
Fig-2b logical connection for current routing protocols
(use VIF technology for if0)
3.Merits and demerits of this design
3.1.Merits
- It is not necessary to modify other stations because
modifications are needed only at feeds and receivers.
- Current routing protocols may be used without any changes.
3.2.Demerits
- It is necessary to prepare another system
for a feed and receivers
to obtain the BDL network addresses of each other
to initialize the tunneling path.
To avoid this demerits,
Dynamic Tunneling Path Configuration is necessary.
This is discussed in another document.
- Overhead of tunneling Network
If we can configure the cost of the tunneling link infinity,
only the routing information from the receivers to the feed
pass through the tunneling network with overhead.
I think it is not so major disadvantage
because the overhead is not so big(ex.20 byte per IP packet)
and the routing traffic is smaller than the data traffic.
4.Architecture of VIF
Once IP packet send to the VIF,
if the host is Feed the IP packet directly send to the UDL,
else (it means the host is Receiver) the IP packet
is encapsulation and send another NIF and
send to the BDL.
IP over IP
| encapsulation
------------- V +-------+
Network Layer IP | IP
(IP Layer) | | |
| | |
------------- V | V
VIF | NIF
Datalink Layer Feed| |Receiver | |
| +------->-------+ |
-------------- | |
V V
Physical Layer UDL BDL
(ex. Satellite link) (ex. Ethernet)
5.Behavior of VIF on Feed and Receiver
1.On Feed
(1)send IP packet to receiver
Network Layer IP
(IP Layer) |
|
------------- V
VIF
Datalink Layer |
|
-------------- |
V
Physical Layer UDL BDL
(ex. Satellite link) (ex. Ethernet)
In case of sending on Feed
(2)receive IP packet from receiver
if encapsulated
^ IP packet
| +-------+
Network Layer IP | |
(IP Layer) ^ | |
| | |
------------- +---------<------+ |
VIF NIF
Datalink Layer |
|
-------------- |
^
Physical Layer UDL BDL
(ex. Satellite link) (ex. Ethernet)
In case of receiving on receiver
2.On Receiver
(1)send IP packet to feed
IP over IP
| encapsulation
------------- V +-------+
Network Layer IP | IP
(IP Layer) | | |
| | |
------------- V | V
VIF | NIF
Datalink Layer | | |
+------->--------+ |
-------------- |
V
Physical Layer UDL BDL
(ex. Satellite link) (ex. Ethernet)
In case of sending on Feed
(2)receive IP packet from feed
^
|
Network Layer IP
(IP Layer) ^
|
------------- |
VIF
Datalink Layer |
|
-------------- |
^
Physical Layer UDL BDL
(ex. Satellite link) (ex. Ethernet)
In case of receiving on receiver
6.Tunnels
The IP encapsulation technique for tunnels
is described in [1], RFC2003[2].
+------------------+
| Outer IP Header |
+------------------+ +------------------+
| IP Header | encapsulation | IP Header |
+------------------+ ===============> +------------------+
| IP Payload | | IP Payload |
+------------------+ +------------------+
An outer IP header is added before the original IP header.
The outer IP header source and destination identify the
"endpoints" of tunnel, Feed and Receiver.
In order to make the path from the receiver to the feed
look as if they are directly connected by using tunneling,
they both have to know their own BDL network address and
UDL network address, along with their peer's BDL network
address and UDL network address.
A receiver or feed may obtain
its own BDL network address and UDL network address
because the administrator configures them,
but another system is needed to obtain
a peer's BDL network address and UDL network address.
The current implementation employs static configuration,
but dynamic configuration is possible
by using the Dynamic Tunneling Path Configuration
described in another document.
When the feed and receiver obtain
the other's BDL network address and UDL network address,
they record the peer's (UDL network address, BDL network address)
in the kernel
and set up the UDL network interface.
The following is an example.
UDL(203.178.140.128/27)
------->------------------>-------
| |
|if0: 203.178.140.129 |if0: 203.178.140.130
+--------+ +--------+
| Feed | |Receiver|
+----+---+ +--------+
|if1: 203.178.141.18 |if1: 203.178.141.196
| |
| +--------+ |
=============| Router |===========
BDL +--------+ BDL
(203.178.141.0/27) (203.178.141.128/27)
Fig. network configuration of example network
At the feed,
the UDL network interface if0 is setup as:
203.178.140.129 netmask 0xffffffe0
the record as:
src bdl address 203.178.141.18,
(dst udl addr 203.178.140.130, dst bdl addr 203.178.141.196)
and the flag indicating the feed is turned on.
The pairs of (dst UDL addr, dst BDL addr) are
provided along the number of receivers.
At the receiver, the UDL network interface if0 is also setup as:
203.178.140.130 netmask 0xffffffe0
the record as:
src bdl address 203.178.141.196,
(dst udl addr 203.178.140.129, dst bdl addr 203.178.141.18)
and the flag indicating the feed is left alone.
7. Bibliography
[1] Noritoshi Demizu and Suguru Yamaguchi,
"DDT --- A Versatile Tunneling Technology",
Proceedings of INET'94/JENC5, 1994
[2] C. Perkins IBM,
"IP Encapsulation within IP",
REC2003, October 1996.