Layering of L3 interfaces on RPR mac
"Vinay Bannai" <[email protected]> Fri, 22 Nov 2002 11:10:51 -0800
| Newsgroups | gmane.ietf.iporpr |
|---|---|
| Message-ID | <[email protected]> |
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Hi folks,
I have written a proposal for layering of L3 interfaces (IP interface) =
on RPR Mac to be included in the proposed draft text.
To summarize, the proposal specifies two mechanisms of layering the IP =
interface. The first mechanism (most commonly used) would have one IP =
interface on top of the RPR Mac. The other mechanism would have a IP =
interface per ringlet. This mechanism eventhough more complex would =
provide IP multipath load balancing if one so wishes to not use RPR =
ringlet selection.
Thanks
Vinay Bannai
Luminous Networks
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<DIV><FONT face=3DArial size=3D2>Hi folks,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I have written a proposal for layering =
of L3=20
interfaces (IP interface) on RPR Mac to be included in the proposed =
draft=20
text.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>To summarize, the proposal specifies =
two mechanisms=20
of layering the IP interface. The first mechanism (most commonly used) =
would=20
have one IP interface on top of the RPR Mac. The other mechanism would =
have a IP=20
interface per ringlet. This mechanism eventhough more complex would =
provide IP=20
multipath load balancing if one so wishes to not use RPR ringlet=20
selection.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Vinay Bannai</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Luminous Networks</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV></BODY></HTML>
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The L3 interfaces in a RPR station (node) can be modelled in the =
following
two ways. There are inherent advantages and disadvantages in providing =
both
types of interfaces.
1 .Ring interface
In this configuration, the IP interface (L3 interface) is modelled as a
interface that is layered on top of the RPR mac interface (L2 =
interface).
This is depicted in figure 1.
+-----------------+
| IP |
| Interface |
+--------+--------+
|
|
|
+--------+--------+
| RPR |
| MAC |
+-----------------+
figure 1
In this configuration, the RPR mac is represented as one link. The whole
ring (both ringlets) is viewed as one network. Packets going out of this
kind of interface cannot select ringlet. The RPR mac selects the ringlet
based on the RPR topology. The packets with unicast destination use the
topology DB in RPR mac for selecting ringlets. Similary for broadcast =
and
multicast, the packets can be sent either unidirectionally on either of =
the
ringlets with source/TTL stripping or sent bi-directionally with TTL
stripping.
The ring interface provides a simple and efficient L3 interface to the =
RPR
mac and leaves all the complexity of the multiple ringlets to the RPR =
mac.
However, this interface does not provide any mechanism of selecting the
ringlet direction.
2. Ringlet interface
In this configuration, there are two IP interfaces (L3 interfaces) =
modelled
on top of the RPR mac interface with one IP interface handling ringlet 0 =
and
the other IP interface handling ringlet 1. This is depicted in figure 2.
+-----------------+ +-----------------+
| IP Interface | | IP interface |
| Ringlet 0 | | Ringlet 1 |
+--------+--------+ +--------+--------+
| |
| |
| |
+-------------+-------------+
| RPR |
| MAC |
+---------------------------+
Ringlet 0 | |
--------------------+--------------|---------------------
| Ringlet 1
-----------------------------------+---------------------
figure 2
Each interface is responsible for a ringlet. Data packets sent and =
received
on IP interface associated with ringlet 0 are transmitted and received =
on
ringlet 0. Data packets sent and received on IP interface associated =
with
ringlet 1 are transmitted and received on ringlet 1. The topology DB in =
the
RPR mac is not consulted for choosing the ringlet. Broadcast and =
multicast
traffic are sent unidirectionally with source/TTL stripping.
The ringlet interface provides a more complex L3 interface to the RPR =
mac.
This would also provide the ability to load balance using multipath OSPF =
and
iBGP.
3. Interoperability
The "ring interface" and the "ringlet interfaces" can exist =
simultaneously
on the same ring. However stations using "ring interfaces" need to
configure multiple (two) IP addresses on the same ring interface to be =
part
of both the ringlets.
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