INTERNET DRAFT IS-IS restart March 2003
Network Working Group M. Shand
Internet Draft Les Ginsberg
Expiration Date: September 2003 Cisco Systems
March 2003
Restart signaling for IS-IS
draft-ietf-isis-restart-03.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1].
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 working documents as Internet-
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six months and may be updated, replaced, or obsoleted by other
documents at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
1. Abstract
The IS-IS routing protocol (RFC 1142 [2], ISO/IEC 10589 [3]) is a
link state intra-domain routing protocol. Normally, when an IS-IS
router is restarted, the neighboring routers detect the restart
event and cycle their adjacencies with the restarting router through
the down state. This is necessary in order to invoke the protocol
mechanisms to ensure correct synchronization of the LSP database.
However, the cycling of the adjacency state causes the neighbors to
regenerate their LSPs describing the adjacency concerned. This in
turn causes temporary disruption of routes passing through the
restarting router.
In certain scenarios such temporary disruption of the routes is
highly undesirable.
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This draft describes a mechanism for a restarting router to signal
that it is restarting to its neighbors, and allow them to
reestablish their adjacencies without cycling through the down
state, while still correctly initiating database synchronization.
When such a router is restarted, it is highly desirable that it does
not recompute its own routes until it has achieved database
synchronization with its neighbors. Recomputing its routes before
synchronization is achieved will result in its own routes being
temporarily incorrect.
This draft additionally describes a mechanism for a restarting
router to determine when it has achieved synchronization with its
neighbors.
This draft additionally describes a mechanism to optimize database
synchronization and minimize transient routing disruption when a
router starts.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119 [4].
If the control and forwarding functions in a router can be
maintained independently, it is possible for the forwarding function
state to be maintained across a control function restart. This
functionality is assumed when the terms "restart/restarting" are
used in this document.
The terms "start/starting" are used to refer to a router in which
the control function has either been started for the first time or
has been restarted but the forwarding functions have not been
maintained in a prior state.
The terms "(re)start/(re)starting" are used when the text is
applicable to both a "starting" and a "restarting" router.
3. Overview
There are two related problems with the existing specification of
IS-IS with regard to synchronization of LSP databases when a router
is restarted.
Firstly, when a routing process restarts and an adjacency to a
neighboring router is reinitialized the neighboring routing process
does three things:
1. It reinitializes the adjacency and causes its own LSP(s) to be
regenerated, thus triggering SPF runs throughout the area (or
in the case of Level 2, throughout the domain).
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2. It sets SRMflags on its own LSP database on the adjacency
concerned.
3. In the case of a Point-to-Point link it transmits a (set of)
CSNP(s) over the adjacency.
In the case of a restarting router process, the first of these is
highly undesirable, but the second is essential in order to ensure
synchronization of the LSP database.
Secondly, whether or not the router is being restarted, it is
desirable to be able to determine when the LSP databases of the
neighboring routers have been synchronized (so that the overload bit
can be cleared in the router's own LSP, for example). This document
describes modifications to achieve this.
It is assumed that the three-way handshake [5] is being used on
Point-to-Point circuits.
4. Approach
4.1 Timers
Three additional timers, T1, T2 and T3 are required to support the
functionality defined in this document.
An instance of T1 is maintained per interface, and indicates the
time after which an unacknowledged (re)start attempt will be
repeated. A typical value might be 3 seconds.
An instance of T2 is maintained for each LSP database present in the
system i.e. for a Level1/2 system, there will be an instance of T2
for Level 1 and an instance for Level 2. This is the maximum time
that the system will wait for LSPDB synchronization. A typical value
might be 60 seconds.
A single instance of T3 is maintained for the entire system. It
indicates the time after which the router will declare that it has
failed to achieve database synchronization (by setting the overload
bit in its own LSP). This is initialized to 65535 seconds, but is
set to the minimum of the remaining times of received IIHs
containing a restart TLV with RA set.
4.2 Restart TLV
A new TLV is defined to be included in IIH PDUs. The presence of
this TLV indicates that the sender supports the functionality
defined in this document and it carries flags that are used to
convey information during a (re)start. All IIHs transmitted by a
router that supports this capability MUST include this TLV.
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Type 211
Length 3
Value (3 octets)
Flags (1 octet)
Bit 1 - Restart Request (RR)
Bit 2 - Restart Acknowledgment (RA)
Bit 3 û Suppress adjacency advertisement(SA)
Bits 4-8 û Reserved
Remaining Time (2 octets)
Remaining holding time (in seconds)
(note: only required when RA bit is set)
4.2.1 Use of RR and RA bits
The RR bit is used by a (re)starting router to signal to its
neighbors that a (re)start is in progress, that an existing
adjacency should be maintained even under circumstances when the
normal operation of the adjacency state machine would require the
adjacency to be reinitialized, and to request a set of CSNPs.
The RA bit is sent by the neighbor of a (re)starting router to
acknowledge the receipt of a restart TLV with the RR bit set.
When the neighbor of a (re)starting router receives an IIH with the
restart TLV having the RR bit set, if there exists on this interface
an adjacency in state "Up" with the same System ID, and in the case
of a LAN circuit, with the same source LAN address, then,
irrespective of the other contents of the "Intermediate System
Neighbors" option (LAN circuits), or the "Point-to-Point Adjacency
State" option (Point-to-Point circuits):
a) The state of the adjacency is not changed. It is an
implementation choice whether or not the holding time of the
adjacency is refreshed. Not refreshing the holding time preserves
the intention of the original holding time. Refreshing it may
allow a longer grace period for the completion of the (re)start
process. Whichever option is chosen, the "remaining time"
transmitted according to (b) below MUST reflect the actual time
after which the adjacency will now expire.
b) immediately (i.e. without waiting for any currently running timer
interval to expire, but with a small random delay of a few 10s of
milliseconds on LANs to avoid "storms"), transmit over the
corresponding interface an IIH including the restart TLV with the
RR bit clear and the RA bit set, having updated the "Point-to-
Point Adjacency State" option to reflect any new values received
from the (re)starting router. (This allows a restarting router to
quickly acquire the correct information to place in its hellos.)
The "Remaining Time" MUST be set to the current time (in seconds)
before the holding timer on this adjacency is due to expire. This
IIH SHOULD be transmitted before any LSPs or SNPs transmitted as a
result of the receipt of the original IIH.
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c) if the corresponding interface is a Point-to-Point interface, or
if the receiving router has the highest LnRouterPriority (with
highest source MAC address breaking ties) among those routers
whose IIHs contain the restart TLV, excluding the transmitting
router (note the actual DIS is NOT changed by this process.),
initiate the transmission over the corresponding interface of a
complete set of CSNPs, and set SRMflags on the corresponding
interface for all LSPs in the local LSP database.
Otherwise (i.e. if there was no adjacency in the "UP" state to the
system ID in question), process the IIH as normal by reinitializing
the adjacency, and setting the RA bit in the returned IIH.
4.2.2 Use of SA bit
The SA bit is used by a starting router to request that its neighbor
suppress advertisement of the adjacency to the starting router in
the neighbors LSPs.
A router which is starting has no maintained forwarding function
state. This may or may not be the first time the router has started.
If this is not the first time the router has started, copies of LSPs
generated by this router in its previous incarnation may exist in
the LSP databases of other routers in the network. These copies are
likely to appear "newer" than LSPs initially generated by the
starting router due to the reinitialization of LSP fragment sequence
numbers by the starting router. This may cause temporary blackholes
to occur until the normal operation of the update process causes the
starting router to regenerate and flood copies of its own LSPs with
higher sequence numbers. The temporary blackholes can be avoided if
the starting router's neighbors suppress advertising an adjacency to
the starting router until the starting router has been able to
propagate newer versions of LSPs generated by previous incarnations.
When the neighbor of a starting router receives an IIH with the
restart TLV having the SA bit set, if there exists on this interface
an adjacency in state "Up" with the same System ID, and in the case
of a LAN circuit, with the same source LAN address, then
advertisement of the adjacency to the starting router in LSPs should
be suppressed. Until an IIH with the SA bit clear has been received,
the adjacency advertisement should continue to be suppressed. If the
adjacency transitions to the UP state, the new adjacency should not
be advertised until an IIH with the SA bit clear has been received.
4.3 Adjacency (re)acquisition
Adjacency (re)acquisition is the first step in (re)initialization.
Both restarting and starting routers will make use of the RR bit in
the restart TLV, though at different stages of the (re)start
procedure.
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4.3.1 Adjacency reacquisition during restart
The restarting router explicitly notifies its neighbor that the
adjacency is being reacquired, and hence that it should not
reinitialize the adjacency. This is achieved by setting the RR bit
in the restart TLV. When the neighbor of a restarting router
receives an IIH with the restart TLV having the RR bit set, if there
exists on this interface an adjacency in state "Up" with the same
System ID, and in the case of a LAN circuit, with the same source
LAN address, then the procedures described in 4.2.1 are followed.
A router that does not support the restart capability will ignore
the restart TLV and reinitialize the adjacency as normal, returning
an IIH without the restart TLV.
On restarting, a router initializes the timer T3, starts timer T2
for each LSPDB and for each interface (and in the case of a LAN
circuit, for each level) starts a timer T1 and transmits an IIH
containing the restart TLV with the RR bit set.
On a Point-to-Point circuit the "Point-to-Point Adjacency State"
SHOULD be set to "Init", because the receipt of the acknowledging
IIH (with RA set) MUST cause the adjacency to enter "Up" state
immediately.
On a LAN circuit the LAN-ID assigned to the circuit SHOULD be the
same as that used prior to the restart. In particular, for any
circuits for which the restarting router was previously DIS, the use
of a different LAN-ID would necessitate the generation of a new set
of pseudonode LSPs, and corresponding changes in all the LSPs
referencing them from other routers on the LAN. By preserving the
LAN-ID across the restart, this churn can be prevented. To enable a
restarting router to learn the LAN-ID used prior to restart, the
LAN-ID specified in an IIH w RR set MUST be ignored.
Transmission of "normal" IIHs is inhibited until the conditions
described below are met (in order to avoid causing an unnecessary
adjacency reinitialization). On expiry of the timer T1, it is
restarted and the IIH is retransmitted as above.
On receipt of an IIH by the restarting router, a local adjacency is
established as usual, and if the IIH contains a restart TLV with the
RA bit set, the receipt of the acknowledgement over that interface
is noted.
T3 is set to the minimum of its current value and the value of the
"Remaining Time" field in the received IIH.
Receipt of an IIH not containing the restart TLV is also treated as
an acknowledgement, since it indicates that the neighbor is not
restart capable. In this case the neighbor will have reinitialized
the adjacency as normal, which in the case of a Point-to-Point link
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will guarantee that SRMflags have been set on its database, thus
ensuring eventual LSPDB synchronization. In the case of a LAN
interface, the usual operation of the update process will also
ensure that synchronization is eventually achieved. However, since
no CSNP is guaranteed to be received over this interface, T1 is
cancelled immediately without waiting for a CSNP. Synchronization
may therefore be deemed complete even though there are some LSPs
which are held(only) by this neighbor (see section 4.4).
In the case of a Point-to-Point circuit, the "LocalCircuitID" and
"Extended Local Circuit ID" information contained in the IIH can be
used immediately to generate an IIH containing the correct 3-way
handshake information. The presence of "Neighbor System ID" or
"Neighbor Extended Local Circuit ID" information which does not
match the values currently in use by the local system is ignored
(since the IIH may have been transmitted before the neighbor had
received the new values from the restarting router), but the
adjacency remains in the initializing state until the correct
information is received.
In the case of a LAN circuit the information in the Intermediate
Systems Neighbors option is recorded and used for the generation of
subsequent IIHs as normal.
When BOTH a complete set of CSNP(s) (for each active level, in the
case of a pt-pt circuit) and an acknowledgement have been received
over the interface, the timer T1 is cancelled.
Once T3 has expired or been cancelled, subsequent IIHs are
transmitted according to the normal algorithms, but including the
restart TLV with both RR and RA clear.
If a LAN contains a mixture of systems, only some of which support
the new algorithm, database synchronization is still guaranteed, but
the "old" systems will have reinitialized their adjacencies.
If an interface is active, but does not have any neighboring router
reachable over that interface the timer T1 would never be cancelled,
and according to clause 4.4.1.1 the SPF would never be run.
Therefore timer T1 is cancelled after some pre-determined number of
expirations (which MAY be 1). (By this time any existing adjacency
on a remote system would probably have expired anyway.)
A router which supports restart SHOULD ensure that the holding time
of any IIHs it transmits is greater than the expected time to
complete a restart. However, where this is impracticable or
undesirable a router MAY transmit one or more normal IIHs
(containing a restart TLV with RR and RA clear) after the initial
RR/RA exchange, but before synchronization has been achieved, in
order to extend the holding time of the neighbors adjacencies beyond
that indicated in the remaining time field of the neighbors IIH with
the RA bit set.
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4.3.2 Adjacency acquisition during start
The starting router wants to ensure that in the event a neighboring
router has an adjacency to the starting router in the UP state (from
a previous incarnation of the starting router) that this adjacency
is reinitialized. The starting router also wants neighboring routers
to suppress advertisement of an adjacency to the starting router
until LSP database synchronization is achieved. This is achieved by
sending IIHs with the RR bit clear and the SA bit set in the restart
TLV. The RR bit remains clear and the SA bit remains set in
subsequent transmissions of IIHs until the adjacency has reached the
UP state and the initial T1 timer interval (see below) has expired.
Receipt of an IIH with RR bit clear will result in the neighboring
router utilizing normal operation of the adjacency state machine.
This will ensure that any old adjacency on the neighboring router
will be reinitialized.
On receipt of an IIH with SA bit set the behavior described in 4.2.2
is followed.
On starting, a router initializes the timer T3, and starts timer T2
for each LSPDB.
For each interface (and in the case of a LAN circuit, for each
level), when an adjacency reaches the UP state, the starting router
starts a timer T1 and transmits an IIH containing the restart TLV
with the RR bit clear and SA bit set. On expiry of the timer T1, it
is restarted and the IIH is retransmitted with both RR and SA bits
set(only the RR bit has changed state from earlier IIHs).
On receipt of an IIH with RR bit set(regardless of whether SA is set
or not) the behavior described in 4.2.1 is followed.
When an IIH is received by the starting router and the IIH contains
a restart TLV with the RA bit set, the receipt of the
acknowledgement over that interface is noted.
T3 is set to the minimum of its current value and the value of the
"Remaining Time" field in the received IIH.
Receipt of an IIH not containing the restart TLV is also treated as
an acknowledgement, since it indicates that the neighbor is not
restart capable. In this case the neighbor will have reinitialized
the adjacency as normal, which in the case of a Point-to-Point link
will guarantee that SRMflags have been set on its database, thus
ensuring eventual LSPDB synchronization. In the case of a LAN
interface, the usual operation of the update process will also
ensure that synchronization is eventually achieved. However, since
no CSNP is guaranteed to be received over this interface, T1 is
cancelled immediately without waiting for a CSNP. Synchronization
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may therefore be deemed complete even though there are some LSPs
which are held(only) by this neighbor (see section 4.4).
When BOTH a complete set of CSNP(s) (for each active level, in the
case of a pt-pt circuit) and an acknowledgement have been received
over the interface, the timer T1 is cancelled. Subsequent IIHs sent
by the starting router have the RR and RA bits clear and the SA bit
set in the restart TLV.
Once T3 has expired or been cancelled, subsequent IIHs are
transmitted according to the normal algorithms, but including the
restart TLV with RR, RA, and SA bits clear.
Timer T1 is cancelled after some pre-determined number of
expirations (which MAY be 1).
During the period when T1 is active, according to the rules defined
in 4.3 the neighbor of the starting router may choose not to update
the holding time for an adjacency because the RR bit is set in the
received IIH. To prevent holding time expiration a starting router
MAY transmit one or more IIHs containing a restart TLV with RR and
RA bits clear and SA bit set after the initial RR/RA exchange.
When T2 is cancelled or expires transmission of "normal" IIHs (with
RR,RA, and SA bits clear) will begin.
4.3.3 Multiple levels
A router which is operating as both a Level 1 and a Level 2 router
on a particular interface MUST perform the above operations for each
level.
On a LAN interface, it MUST send and receive both Level 1 and
Level 2 IIHs and perform the CSNP synchronizations independently for
each level.
On a pt-pt interface, only a single IIH (indicating support for both
levels) is required, but it MUST perform the CSNP synchronizations
independently for each level.
4.4 Database synchronization
When a router is started or restarted it can expect to receive a
(set of) CSNP(s) over each interface. The arrival of the CSNP(s) is
now guaranteed, since an IIH with RR bit set will be retransmitted
until the CSNP(s) are correctly received.
The CSNPs describe the set of LSPs that are currently held by each
neighbor. Synchronization will be complete when all these LSPs have
been received.
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When (re)starting, a router starts the timer T3 and an instance of
timer T2 for each LSPDB as described in 4.3.1 or 4.3.2. In addition
to normal processing of the CSNPs, the set of LSPIDs contained in
the first complete set of CSNP(s) received over each interface is
recorded, together with their remaining lifetime. If there are
multiple interfaces on the (re)starting router, the recorded set of
LSPIDs is the union of those received over each interface. LSPs with
a remaining lifetime of zero are NOT so recorded.
As LSPs are received (by the normal operation of the update process)
over any interface, the corresponding LSPID entry is removed (it is
also removed if the LSP had arrived before the CSNP containing the
reference). When an LSPID has been held in the list for its
indicated remaining lifetime, it is removed from the list. When the
list of LSPIDs is empty and T1 has been cancelled for all the
interfaces that have an adjacency at this level, the timer T2 is
cancelled.
At this point the local database is guaranteed to contain all the
LSP(s) (either the same sequence number, or a more recent sequence
number) which were present in the neighbors' databases at the time
of (re)starting. LSPs that arrived in a neighbor's database after
the time of (re)starting may, or may not, be present, but the normal
operation of the update process will guarantee that they will
eventually be received. At this point the local database is deemed
to be "synchronized".
Since LSPs mentioned in the CSNP(s) with a zero remaining lifetime
are not recorded, and those with a short remaining lifetime are
deleted from the list when the lifetime expires, cancellation of the
timer T2 will not be prevented by waiting for an LSP that will never
arrive.
4.4.1 LSP generation and flooding and SPF computation
The operation of a router starting, as opposed to restarting is
somewhat different. These two cases are dealt with separately below.
4.4.1.1. Restarting
In order to avoid causing unnecessary routing churn in other
routers, it is highly desirable that the own LSPs generated by the
restarting system are the same as those previously present in the
network (assuming no other changes have taken place). It is
important therefore not to regenerate and flood the LSPs until all
the adjacencies have been re-established and any information
required for propagation into the local LSPs is fully available.
Ideally, the information should be loaded into the LSPs in a
deterministic way, such that the same information occurs in the same
place in the same LSP (and hence the LSPs are identical to their
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previous versions). If this can be achieved, the new versions will
not even cause SPF to be run in other systems. However, provided the
same information is included in the set of LSPs (albeit in a
different order, and possibly different LSPs), the result of running
the SPF will be the same and will not cause churn to the forwarding
tables.
In the case of a restarting router, none of the router's LSPs are
transmitted, nor are the router's own forwarding tables updated
while the timer T3 is running.
Redistribution of inter-level information must be regenerated before
this router's LSP is flooded to other nodes. Therefore the Level-n
non-pseudonode LSP(s) should not be flooded until the other level's
T2 timer has expired and its SPF has been run. This ensures that any
inter-level information that should be propagated can be included in
the Level-n LSP(s).
During this period, if one of the router's own (including
pseudonodes) LSPs is received, which the local router does not
currently have in its own database, it is NOT purged. Under normal
operation, such an LSP would be purged, since the LSP clearly should
not be present in the global LSP database. However, in the present
circumstances, this would be highly undesirable, because it could
cause premature removal of an own LSP -- and hence churn in remote
routers. Even if the local system has one or more own LSPs (which it
has generated, but not yet transmitted) it is still not valid to
compare the received LSP against this set, since it may be that as a
result of propagation between Level 1 and Level 2 (or vice versa) a
further own LSP will need to be generated when the LSP databases
have synchronized.
During this period a restarting router SHOULD send CSNPs as it
normally would. Information about the router's own LSPs MAY be
included, but if it is included it MUST be based on LSPs which have
been received, not on versions which have been generated(but not yet
transmitted). This restriction is necessary to prevent premature
removal of an LSP from the global LSP database.
When the timer T2 expires or is cancelled indicating that
synchronization for that level is complete, the SPF for that level
is run in order to derive any information which is required to be
propagated to another level, but the forwarding tables are not yet
updated.
Once the other level's SPF has run and any inter-level propagation
has been resolved, the 'own' LSPs can be generated and flooded. Any
'own' LSPs which were previously ignored, but which are not part of
the current set of 'own' LSPs (including pseudonodes) should then be
purged. Note that it is possible that a Designated Router change may
have taken place, and consequently the router should purge those
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pseudonode LSPs which it previously owned, but which are now no
longer part of its set of pseudonode LSPs.
When all the T2 timers have expired or been cancelled, the timer T3
is cancelled and the local forwarding tables are updated.
If the timer T3 expires before all the T2 timers have expired or
been cancelled, this indicates that the synchronization process is
taking longer than minimum holding time of the neighbors. The
router's own LSP(s) for levels which have not yet completed their
first SPF computation are then flooded with the overload bit set to
indicate that the router's LSPDB is not yet synchronized (and other
routers should therefore not compute routes through this router).
Normal operation of the update process resumes and the local
forwarding tables are updated. In order to prevent the neighbor's
adjacencies from expiring, IIHs with the normal interface value for
the holding time are transmitted over all interfaces with neither RR
nor RA set in the restart TLV. This will cause the neighbors to
refresh their adjacencies. The own LSP(s) will continue to have the
overload bit set until timer T2 has expired or been cancelled.
4.4.1.2. Starting
In the case of a starting router, as soon as each adjacency is
established, and before any CSNP exchanges, the router's own zeroth
LSP is transmitted with the overload bit set. This prevents other
routers from computing routes through the router until it has
reliably acquired the complete set of LSPs. The overload bit remains
set in subsequent transmissions of the zeroth LSP (such as will
occur if a previous copy of the routers LSP is still present in the
network) while any timer T2 is running.
When all the T2 timers have been cancelled, the own LSP(s) MAY be
regenerated with the overload bit clear (assuming the router isn't
in fact overloaded, and there is no other reason, such as incomplete
BGP convergence, to keep the overload bit set), and flooded as
normal.
Other 'own' LSPs (including pseudonodes) are generated and flooded
as normal, irrespective of the timer T2. The SPF is also run as
normal and the RIB and FIB updated as routes become available.
To avoid the possible formation of temporary blackholes the starting
router sets the SA bit in the restart TLV (as described in 4.3.2) in
all IIHs that it sends.
When all T2 timers have been cancelled, the starting router MUST
transmit IIHs with the SA bit clear.
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5. Security Considerations
This memo does not create any new security issues for the IS-IS
protocol. Security considerations for the base IS-IS protocol are
covered in [2] and [3].
6. References
1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
2 Callon, R., "OSI IS-IS for IP and Dual Environment," RFC 1195,
December 1990.
3 ISO, "Intermediate system to Intermediate system routeing
information exchange protocol for use in conjunction with the
Protocol for providing the Connectionless-mode Network Service
(ISO 8473)," ISO/IEC 10589:2002, Second Edition.
4 Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997
5 Katz, D., "Three-Way Handshake for IS-IS Point-to-Point
Adjacencies", RFC 3373, September 2002
7. Acknowledgments
The authors would like to acknowledge contributions made by Radia
Perlman, Mark Schaefer, Naiming Shen, Nischal Sheth, Russ White, and
Rena Yang.
8. Authors' Addresses
Mike Shand
Cisco Systems
250 Longwater Avenue,
Reading,
Berkshire,
RG2 6GB
UK
Phone: +44 208 824 8690
Email: mshand@cisco.com
Les Ginsberg
Cisco Systems
510 McCarthy Blvd.
Milpitas, Ca. 95035 USA
Email: ginsberg@cisco.com
Shand, Ginsberg Expires Sep 2003 [Page 13]
