INTERNET DRAFT EXPIRES JUNE 1999 INTERNET DRAFT
Network Working Group D. Hamilton
D. Ruffen
Category: Informational Cabletron Systems Incorporated
December 1998
Cabletron's VlanHello Protocol Specification
Version 4
<draft-rfced-info-cabletron-hello-00.txt>
Status of This Memo
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Distribution of this document is unlimited.
Abstract
The VlanHello protocol is part of the InterSwitch Message
Protocol (ISMP) which provides interswitch communication
between switches running Cabletron's SecureFast VLAN
(SFVLAN) product. Switches use the VlanHello protocol to
discover their neighboring switches and establish the
topology of the switch fabric.
Table of Contents
Status of this Memo.................................. 1
Copyright Notice..................................... 1
Abstract............................................. 1
1. Introduction...................................... 2
1.1 Data Conventions.............................. 2
2. VlanHello Protocol Operational Overview........... 3
2.1 Neighbor Discovery............................ 3
2.2 Port States................................... 3
2.3 Topology Events............................... 6
2.4 Timers........................................ 9
3. InterSwitch Message Protocol...................... 10
3.1 Frame Header.................................. 10
3.2 ISMP Packet Header............................ 11
3.3 ISMP Message Body............................. 12
4. Interswitch Keepalive Message..................... 13
5. Security Considerations........................... 16
6. References........................................ 16
7. Authors' Addresses................................ 16
8. Full Copyright Statement.......................... 17
Hamilton & Ruffen Informational [Page 1]
1. Introduction
This memo is being distributed to members of the Internet
community in order to solicit reactions to the proposals
contained herein. While the specification discussed here
may not be directly relevant to the research problems of the
Internet, it may be of interest to researchers and
implementers.
1.1 Data Conventions
The methods used in this memo to describe and picture data
adhere to the standards of Internet Protocol documentation
[RFC1700], in particular:
The convention in the documentation of Internet
Protocols is to express numbers in decimal and to
picture data in "big-endian" order. That is, fields
are described left to right, with the most
significant octet on the left and the least
significant octet on the right.
The order of transmission of the header and data
described in this document is resolved to the octet
level. Whenever a diagram shows a group of octets,
the order of transmission of those octets is the
normal order in which they are read in English.
Whenever an octet represents a numeric quantity the
left most bit in the diagram is the high order or
most significant bit. That is, the bit labeled 0 is
the most significant bit.
Similarly, whenever a multi-octet field represents a
numeric quantity the left most bit of the whole
field is the most significant bit. When a multi-
octet quantity is transmitted the most significant
octet is transmitted first.
Hamilton & Ruffen Informational [Page 2]
2. VlanHello Protocol Operational Overview
Switches use the VlanHello protocol to detect their
neighboring switches and establish the topology of the
switch fabric.
2.1 Neighbor Discovery
At initialization, each switch sends an Interswitch
Keepalive message out all local ports except those which
have been preconfigured such that they cannot be Network
ports (see Section 2.2). Then, as each switch discovers its
neighboring switches via incoming Interswitch Keepalive
messages, it notifies its local topology services (see
Section 2.3), which then build the topology tables for the
switching fabric.
Each switch continues to send Interswitch Keepalive messages
at regular intervals (currently 5 seconds). If a switch has
not heard from one of its neighbors for some predetermined
interval (see Section 2.4), notification is sent to all
interested services and the neighboring switch is removed
from the topology table.
Interswitch Keepalive messages are described in Section 4.
2.2 Port States
Each port on a switch can be in one of several different
states. These states are listed below. Figure 1 shows how
the port state changes within the VlanHello protocol.
o Unknown. This is the default state of all ports at
initialization.
o Network. A port is deemed a Network port when the switch
has received an Interswitch Keepalive message over the
port from one of its neighbor switches. A transition to
this state triggers a Neighbor Found event, notifying the
local topology servers that the interface is functioning
and a 2-way conversation has been established with the
neighbor.
When the last switch is lost on a Network port, the state
of the switch reverts to either Network Only (see next
state) or to Unknown, and a Neighbor Lost event is
triggered, notifying the local topology servers that the
interface is no longer operational.
Hamilton & Ruffen Informational [Page 3]
o Network Only. Certain types of port interfaces are
incapable of accessing user endstations and can only be
used to access other switches. Such ports are deemed
Network Only ports. If the last switch is lost from a
port that has already been deemed a Network port, the
VlanHello protocol checks the condition of the port
interface. If it is the type of interface that can only
be used to access other switches, the state of the port
is set to Network Only. Otherwise, it reverts to
Unknown.
o Standby. A port is deemed a Standby port under the
following conditions:
o The neighbor switch on the port has a higher level of
functionality and it has determined that the local
switch is incompatible with that functionality. In
this circumstance, the MAC entry for the local switch
in the Interswitch Keepalive message received from the
neighbor contains an assigned status of Incompatible.
o The list of MAC entries in the Interswitch Keepalive
message received from the neighbor switch does not
contain an entry for the local switch. In this
circumstance, the local switch assumes that
communication with its neighbor will be one-way only.
The VlanHello protocol continues to listen for
Interswitch Keepalive messages on a Standby port, but
does not transmit any Interswitch Keepalive messages over
the port. If a message is received that removes the
condition under which the port state was set to Standby,
the state of the port is set to Network.
o Going to Access. When any packet other than an
Interswitch Keepalive message is received over an Unknown
port, the state of the port is changed to Going to Access
and a timer is activated. If the timer expires without
an Interswitch Keepalive message being received over the
port, the port state changes to Access.
o Access. A port is deemed an Access port when any packet
other than an Interswitch Keepalive message has been
received over the port and the Going to Access timer has
expired. A port can also be administratively designated
an Access "control" port, meaning the port is to remain
an Access port, regardless of the type of messages that
are received on it. Interswitch Keepalive messages are
not sent over Access control ports.
Hamilton & Ruffen Informational [Page 4]
Three other types of ports are recognized: the host
management port, host data port, and host control port.
These ports are designated at initialization and are used to
access the host CPU. Interswitch Keepalive messages are not
sent over these ports.
Packet in
|
V
+---------+
Packet in | Unknown |
| +---------+
G-A V |
Timer +----------+ no V
exp | Going to |<------[KA msg?] Packet in
<------| Access | | |
| +----------+ yes | V
V | V yes +---------+
+--------+ V [1-way?]------+-->| Standby |
| Access | [KA msg?] | ^ +---------+
+--------+ | | no | |
| V no | V
yes | [compatible?]----+ [KA msg?]
| | |
| | yes | yes
| V V
V +---------+ [1-way?]
+--------->| Network |<--+ |
+---------+ ^ | no
| | yes V
lost last | +<----[compatible?]
neighbor |
V
[network]
[ only? ]
|
+--------------+ yes | no +---------+
| Network Only |<-----------+----------->| Unknown |
+--------------+ +---------+
Figure 1: Port State Machine
Hamilton & Ruffen Informational [Page 5]
2.3 Topology Events
When the VlanHello protocol discovers new information about
the status of one of its network ports, it notifies its local
topology service center so that the service center can build
or modify the topology tables for the switch fabric. This
notification takes the form of a system event, described in
a structure known as a topology relay structure. These
structures are linked in a first-in/first-out (FIFO) queue
and processed by the topology servers in the order in which
they were received.
A topology relay structure typically contains information
from Interswitch Keepalive messages received on the specified
port, as shown below.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00 | Event |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
04 | Delta options mask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
08 | Current options mask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | Port number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 | |
+ Port neighbor switch identifier +
| |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Port neighbor IP address ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
28 | ... Port neighbor IP address | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Neighbor chassis MAC addr +
32 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
36 | Neighbor chassis IP address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
40 | Neighbor functional level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
44 | Topology agent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
48 | Next event |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Hamilton & Ruffen Informational [Page 6]
Event
This 4-octet field contains the number of the event.
Valid values are as follows:
1 A new neighbor switch was discovered on the
specified port.
2 The neighbor switch has gained the feature(s)
specified in the Delta options mask.
3 The neighbor switch has lost the feature(s)
specified in the Delta options mask.
4 The neighbor switch has timed out and is presumed
down.
5 The specified port is down.
6 The neighbor switch has been previously seen on a
different port. The specified port is the
previous port.
7 The specified port is being reassigned to another
topology agent. Event is generated by the current
(old) agent.
8 The port is looped -- that is, the Keepalive
message was generated by the receiving switch.
9 The port is crossed -- that is, a Keepalive message
was received on a port not owned by this topology
agent.
10 The neighbor switch's functional level has changed.
11 The neighbor switch is running an incompatible
version of the protocol.
12 Two-way communication with the neighbor switch has
been lost.
13 The neighbor switch's Keepalive message sequence
number has been reset, indicating the switch
itself has been reset.
Delta options mask
This 4-octet field contains a bit map specifying the
feature(s) gained or lost by the neighbor switch (events
2 and 3 only). Valid values are as specified for the next
field, Current options mask.
Current options mask
This 4-octet field contains a bit map specifying the
features of the neighbor switch. Bit assignments are as
follows:
1 (unused)
2 The switch is a VLAN switch.
4 The switch has link state capability.
8 The switch has loop-free flood path capability.
Hamilton & Ruffen Informational [Page 7]
16 The switch has resolve capability.
32 (unused)
64 The switch has tag-based flood capability.
128 The switch has tap capability.
256 The switch has message connection capability.
512 The switch has redundant access capability.
1024 The switch is an isolated switch.
4096 The switch is an uplink. (SFVLAN V1.8 only)
8192 The switch is an uplink to core. (SFVLAN V1.8 only)
16384 The port is an uplink port. (SFVLAN V1.8 only)
32768 The port is an uplink flood port. (SFVLAN V1.8 only)
Port number
This 4-octet field contains the logical number of the local
port for which the event was generated.
Port neighbor switch identifier
This 10-octet field contains the internal identifier of
the neighbor switch discovered on the port. The identifier
consists of the 6-octet physical (MAC) address of the neighbor
switch, followed by the 4-octet logical port number (local to
the neighbor switch) on which the neighbor was discovered.
Port neighbor IP address
This 4-octet field contains the Internet Protocol (IP)
address of the neighbor switch.
Neighbor chassis MAC address
This 6-octet field contains the physical (MAC) address of
the chassis of the neighbor switch.
Neighbor chassis IP address
This 4-octet field contains the Internet Protocol (IP)
address of the chassis of the neighbor switch.
Neighbor functional level
This 4-octet field contains the functional level of the
neighbor switch, as determined by the version level of
the SecureFast VLAN software under which this switch is
operating. Valid values are as follows:
1 The switch is running a version of SFVLAN prior to
Version 1.8.
2 The switch is running SFVLAN Version 1.8 or
greater.
Hamilton & Ruffen Informational [Page 8]
Topology agent
This 4-octet field contains a pointer to the topology agent
that generated the event. The pointer here can reference
any of the topology agents that send Interswitch Keepalive
messages -- that is, any agent running the VlanHello protocol.
Next event
This 4-octet field contains a pointer to the next event relay
structure in the list.
2.4 Timers
The VlanHello protocol uses three timers.
o Send Hello timer. The Send Hello timer is used to
control the interval at which Interswitch Keepalive
messages are sent.
o Aging timer. The Aging Timer is used to detect when
communication with a neighboring switch has been lost.
o Going to Access timer. The Going to Access timer is used
to synchronize the transition of a port state to Access
and prevent a port from being prematurely designation as
an Access port during network initialization. If an
Unknown port receives any packet other than an
Interswitch Keepalive message, the port state is set to
Going To Access. If the switch receives an Interswitch
Keepalive message over that port before the timer
expires, the port state is changed to Network.
Otherwise, when the timer expires, the port state is
changed to Access.
Hamilton & Ruffen Informational [Page 9]
3. InterSwitch Message Protocol
The VlanHello protocol operates as part of the InterSwitch
Message Protocol (ISMP) -- part of Cabletron's SecureFast
VLAN (SFVLAN) product, as described in [IDsfvlan]. ISMP
provides a consistent method of encapsulating and
transmitting network control messages exchanged between
SFVLAN switches.
ISMP message packets are of variable length and have the
following general structure:
o Frame header
o ISMP packet header
o ISMP message body
3.1 Frame Header
ISMP packets are encapsulated within an IEEE 802-compliant
frame using a standard header as shown below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00 | |
+ Destination address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
04 | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Source address +
08 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
16 | |
+ +
: :
Destination address
This 6-octet field contains the Media Access Control (MAC)
address of the multicast channel over which all switches
in the fabric receive ISMP packets. The destination
address fields of all ISMP packets contain a value of
01-00-1D-00-00-00.
Source address
This 6-octet field contains the physical (MAC) address of
the switch originating the ISMP packet.
Hamilton & Ruffen Informational [Page 10]
Type
This 2-octet field identifies the type of data carried
within the frame. The type field of ISMP packets
contains the value 0x81FD.
3.2 ISMP Packet Header
The ISMP packet header consists of a variable number of
octets, as shown below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00 |///////////////////////////////////////////////////////////////|
://////// Frame header /////////////////////////////////////////:
+//////// (14 octets) /////////+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 |///////////////////////////////| ISMP Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 | ISMP message type | Sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
20 | Code length | |
+-+-+-+-+-+-+-+-+ +
| Authentication code |
: :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: :
Frame header
This 14-octet field contains the frame header.
ISMP Version
This 2-octet field contains the version number of the
InterSwitch Message Protocol to which this ISMP packet
adheres. The VlanHello protocol uses ISMP Version 3.0.
ISMP message type
This 2-octet field contains a value indicating which type
of ISMP message is contained within the message body.
VlanHello Interswitch Keepalive messages have a message
type of 2.
Hamilton & Ruffen Informational [Page 11]
Sequence number
This 2-octet field contains an internally generated
sequence number used by the various protocol handlers for
internal synchronization of messages.
Code length
This 1-octet field contains the number of octets in the
Authentication code field of the message.
Authentication code
This variable-length field contains an encoded value used
for authentication of the ISMP message.
3.3 ISMP Message Body
The ISMP message body is a variable-length field containing
the actual data of the ISMP message. The length and content
of this field are determined by the value found in the
message type field.
The format of the VlanHello Interswitch Keepalive message is
described in the next section.
Hamilton & Ruffen Informational [Page 12]
4. Interswitch Keepalive Message
The VlanHello Interswitch Keepalive message consists of a variable
number of octets, as shown below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00 | |
+ Frame header / +
: ISMP packet header :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n | Version | Switch IP address ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n+4 | ... Switch IP address | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
n+8 | |
+ Switch ID +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n+16 | |
+ Chassis MAC address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Chassis IP address ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n+24 | ... Chassis IP address | Switch type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n+28 | Functional level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n+32 | Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n+36 | Base MAC count | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
n+40 | |
: Base MAC entries :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n = 21 + length of the authentication code of the packet
Frame header/ISMP packet header
This variable-length field contains the frame header and the
ISMP packet header.
Version
This 2-octet field contains the version number of the VlanHello
protocol to which this message adheres. This document describes
VlanHello Version 4.
Hamilton & Ruffen Informational [Page 13]
Switch IP address
This 4-octet field contains the Internet Protocol (IP)
address of the sending switch.
Switch ID
This 10-octet field contains the internal ISMP identifier
of the sending switch. The identifier is generated by
the sending switch and consists of the 6-octet physical
(MAC) address of the switch, followed by a 4-octet value
containing the logical port number over which the switch
sent the packet.
Chassis MAC
This 6-octet field contains the physical (MAC) address of
the chassis of the sending switch.
Chassis IP address
This 4-octet field contains the Internet Protocol (IP)
address of the switch chassis.
Switch type
This 2-octet field contains the type of the switch.
Currently, the only value recognized here is as follows:
2 The switch is an SFVLAN switch.
Functional level
This 4-octet field contains the functional level of the
sending switch, as determined by the version level of the
SecureFast VLAN software under which this switch is
operating. Valid values are as follows:
1 The switch is running a version of SFVLAN prior to
Version 1.8.
2 The switch is running SFVLAN Version 1.8 or
greater.
Options
This 4-octet field contains a bit map specifying the
features of the switch. Bit assignments are as follows:
1 (unused)
2 The switch is a VLAN switch.
4 The switch has link state capability.
Hamilton & Ruffen Informational [Page 14]
8 The switch has loop-free flood path capability.
16 The switch has resolve capability.
32 (unused)
64 The switch has tag-based flood capability.
128 The switch has tap capability.
256 The switch has message connection capability.
512 The switch has redundant access capability.
1024 The switch is an isolated switch.
4096 The switch is an uplink. (SFVLAN V1.8 only)
8192 The switch is an uplink to core. (SFVLAN V1.8 only)
16384 The port is an uplink port. (SFVLAN V1.8 only)
32768 The port is an uplink flood port. (SFVLAN V1.8 only)
Base MAC count
This 2-octet field contains the number of entries in the
list of Base MAC entries.
Base MAC entries
This variable-length field contains a list of entries for all
neighboring switches that the sending switch has previously
discovered on the port over which the message was sent.
The number of entries is found in the Base MAC count field.
Each MAC entry is 10 octets long, structured as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Switch MAC address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Assigned neighbor state ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... Assigned neighbor state |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Switch MAC address
This 6-octet field contains the base MAC address of the
neighboring switch.
Assigned neighbor state
This 4-octet field contains the assigned state of the
neighboring switch as perceived by the sending switch.
Currently, the only value valid here is 3, indicating a
state of Network
Hamilton & Ruffen Informational [Page 15]
5. Security Considerations
Security issues are not discussed in this document.
6. References
[RFC1700] Reynolds, S.J., Postel, J. Assigned Numbers.
October 1994.
[IDsfvlan] Ruffen, D., et. al. Cabletron's SecureFast
VLAN Operational Model.
[IDvlsp] Kane, L. Cabletron's VLS Protocol Specification.
7. Authors' Addresses
Cabletron Systems, Inc., is located at:
Post Office Box 5005
Rochester, NH 03866-5005
(603) 332-9400
Dave Hamilton Email: daveh@ctron.com
Dave Ruffen Email: ruffen@ctron.com
Hamilton & Ruffen Informational [Page 16]
8. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document and translations of it may be copied and furnished
to others, and derivative works that comment on or otherwise
explain it or assist in its implementation may be prepared, copied,
published and distributed, in whole or in part, without restriction
of any kind, provided that the above copyright notice and this
paragraph are included on all such copies and derivative works.
However, this document itself may not be modified in any way, such
as by removing the copyright notice or references to the Internet
Society or other Internet organizations, except as needed for the
purpose of developing Internet standards in which case the
procedures for copyrights defined in the Internet Standards process
must be followed, or as required to translate it into languages
other than English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
INTERNET DRAFT EXPIRES JUNE 1999 INTERNET DRAFT