IPv6 Operations Working Group (v6ops) F. Gont
Internet-Draft SI6 Networks
Intended status: Informational 3 March 2025
Expires: 4 September 2025
Problem Statement about IPv6 Support for Multiple Routers, Multiple
Interfaces, and Multiple Prefixes
draft-gont-v6ops-multi-ipv6-02
Abstract
This document discusses current limitations in IPv6 Stateless Address
Auto-configuration (SLAAC) that prevent support for common multi-
router, multi-interface, and multi-prefix scenarios. It provides
discussion on the challenges that these scenarios represent, and why
a solution in this space is warranted. Finally, it specifies a
number of common scenarios that any solution in this space should be
able to address.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 4 September 2025.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Multi-Router Scenario . . . . . . . . . . . . . . . . . . 4
3.2. Multi-Router/Multi-Prefix Failover Scenario . . . . . . . 6
3.3. Multi-Router Failover Scenario . . . . . . . . . . . . . 8
3.4. Multi-Interface Scenario . . . . . . . . . . . . . . . . 9
3.5. Conflicting Information . . . . . . . . . . . . . . . . . 11
4. Prior Work . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
IPv6 Stateless Address Autoconfiguration (SLAAC) [RFC4862] is based
on the assumption that SLAAC routers advertise configuration
information on a local network, and SLAAC hosts will aggregate this
information and use it as they see fits. Im simple network scenarios
where there is a single local router, or where there are multiple
routers but all such routers advertise the same network configuration
information and provide the same service, SLAAC works just fine.
However, other more complex (yet very common) scenarios are currently
unsupported. These scenarios include:
* A host attaches to a local-area network (LAN) that employs two
different routers, one for each upstream Internet Service Provider
(ISP).
* A host attaches to two (or more) different networks via two (or
more) network interfaces.
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* A host attaches to a local-area network, and receives conflicting
information from two or more routers.
In the first two scenarios, a SLAAC host ends up receiving
information from two routers that are managed by different entities
(two different ISPs) and, for all practical purposes, each piece of
configuration information advertised by each router is only of use
when employed in conjunction with the rest of the information
advertised by such router. In other words, mixing configuration
information from different SLAAC advertising routers will usually
lead to interoperability problems.
The third scenario could be considered a corner-case of the first two
scenarios: two or more routers send conflicting information, such as
the same SLAAC configuration information with different lifetimes
(e.g., one SLAAC router advertises a piece of information with a
lifetime of zero, and another advertises the same information with
non-zero lifetime). In this scenario, a single router advertising
configuration information with a lifetime of zero may simply cause
the corresponding information to be e.g. completely discarded from
the host.
Section 2 defines the terminology employed throughout this document.
Section 3 elaborates on a number of scenarios that are generally not
supported by current implementations, which not only serve to
illustrate the problem statement, but also as test cases that any
solution in this space should be able to address gracefully.
Section 5 discusses future work may be needed to address the problem
at hand.
2. Terminology
Multi-prefix scenario:
A network scenario where a host employs two or more IPv6 prefixes
for address configuration with SLAAC. This may be the result of
attaching to two or more networks via two or more network
interfaces, or simply the result of attaching to a single local
network where multiple prefixes are advertised via one or more
SLAAC routers.
Multi-router scenario:
A network scenario where a SLAAC hosts employs two or more SLAAC
routers. This may be the result of attaching to two o more
networks via two or more network interfaces, or simply the result
of attaching to a single local network where multiple prefixes are
advertised via one or more SLAAC routers.
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Multi-interface scenario:
A network scenario where a host employs two or more network
interfaces (without considering the "loopback" interface). Some
bibliography refer to these hosts as being "multihomed". In the
vast majority of cases, hosts employing multiple interfaces will
result in "multi-prefix" and "multi-router" scenarios. In the
specific corner case where a host attaches to the same network via
two (or more) network interfaces, this will typically result in a
multi-router scenario, where the same router that is available via
multiple is interfaces is considered, fo all practical purposes,
as a different router -- .e.g., the same router will result in
different default routes, one via each of the network interfaces.
Multi-IPv6:
The term "Multi-IPv6" (case insensitive) is employed throughout
this document as a short-hand for network scenarios where multiple
IPv6 routers, multiple interfaces, and/or multiple IPv6 prefixes
are employed. We note that "multi-prefix", "multi-interface", and
"multi-router" scenarios are not mutually-exclusive: for instance,
a host that employs multiple interfaces will usually also employ
multiple prefixes and multiple routers.
SLAAC prefix set:
The SLAAC prefix set for an SLAAC router is composed of all
prefixes that are being advertised by the router via SLAAC PIOs
(irrespective of how e.g. the "A" and "L" flags of the PIO were
set).
3. Scenarios
3.1. Multi-Router Scenario
Consider a network scenario where a user attaches two Customer
Premises Equipment (CPE) routers to a local network ("Network_C" in
our example) for improved network resilience, The scenario could be
described as follows:
* Two SLAAC routers (ROUTER_A and ROUTER_B) from different ISPs
(ISP_A and ISP_B, respectively) are attached to Network C
* ROUTER_A advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
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* ISP_A enforces ingress filtering [RFC2827], and implements ACLs
such that RDNSS_A only processes requests from ISP_A customers.
* ROUTER_B advertises:
- Prefix PREFIX_B for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_B) (by means of Recursive DNS
Server option [RFC8106]).
* ISP_B enforces ingress filtering [RFC2827], and implements ACLs
such that RDNSS_B only processes requests from ISP_B customers.
* Host C attaches to Network C, and thus configures:
- Addresses from both prefixes (PREFIX_A and PREFIX_B).
- Two default routers (ROUTER_A and ROUTER_B).
- Two recursive DNS servers: RDNSS_A and RDNSS_B.
In this scenario, Host C may only send traffic from PREFIX_A via
ROUTER_A or from PREFIX_B via ROUTER_B: otherwise, packets will be
dropped as a result of ingress filtering [RFC2827]. Similarly, Host
C may only send DNS queries from PREFIX_A to RDNSS_A, or from
PREFIX_B to RDNSS_B: sending traffic from PREFIX_A to RDNSS_B or from
PREFIX_B to RDNSS_A will result in the ACLs enforced by the
respective ISPs to drop the DNS queries.
It should be noted that it is quite common for DNS responses to
depend on the source address of the query, for improved service. For
example, if the "www.example.com" web site was served via a Content
Delivery Network (CDN), RDNSS_A would likely resolve that domain name
to an IP address that is topologically close to ISP_A, while RDNSS_B
would resolve the same domain name to an address that is
topologically close to ISP_B. In many cases, the corresponding web
cache might be hosted within the ISP network itself. In these
scenarios, using the information learned from RDNSS_A via ISP_B, or
using the information learned via RDNSS_B via ISP_A would likely lead
to sub-optimal service (e.g., larger Round-Trip Time) or no service
(if ACLs were being enforced).
It should be evident that each piece of information being advertised
via SLAAC is only usable when employed in conjunction with the rest
of the information advertised by the same router. However, SLAAC
does not require this behavior: hosts are free to use any piece of
configuration they learn via SLAAC as they see fit.
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As a result of these considerations, in a scenario where e.g.
ROUTER_A becomes unreachable while ROUTER_B is known to be reachable:
* RDNSS_A should not be employed for DNS resolution, since queries
to RDNSS_A would need to be performed from PREFIX_A via ROUTER_A
(considered unreachable). Thus, in this scenario DNS queries
should be performed from PREFIX_B via ROUTER_B to RDNSS_B.
* Cached DNS information learned via RDNSS_A should be removed/
ignored, since they would require that new communication instances
to the corresponding IPv6 addresses would employ addresses from
PREFIX_A via ROUTER_A (considered unreachable).
* New communication instances to an IPv6 literal (i.e., an IPv6
address that has not been learned via the DNS) should not employ
ROUTER_A as the next hop (since it is considered unreachable).
Hence, in this scenarios new communication instances should employ
addresses from PREFIX_B via ROUTER_B.
Section Section 3.2 and Section 3.3 discuss the expected behavior in
two specific failure cases.
3.2. Multi-Router/Multi-Prefix Failover Scenario
Consider a network scenario where a user attaches two Customer
Premises Equipment (CPE) routers from different ISPs to a local
network ("Network_C" in our example) for improved network resilience,
The scenario could be described as follows:
* Two SLAAC routers (ROUTER_A and ROUTER_B) from different ISPs
(ISP_A and ISP_B, respectively) are attached to Network C
* ROUTER_A advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* ISP_A enforces ingress filtering [RFC2827], and implements ACLs
such that RDNSS_A only processes requests from ISP_A customers.
* ROUTER_B advertises:
- Prefix PREFIX_B for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
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- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* ISP_B enforces ingress filtering [RFC2827], and implements ACLs
such that RDNSS_B only processes requests from ISP_B customers.
* Host C attaches to Network C, and thus configures:
- Addresses from both prefixes (PREFIX_A and PREFIX_B).
- Two default routers (ROUTER_A and ROUTER_B).
- One recursive DNS server (RDNSS_A).
Consider the case where e.g. ROUTER_A becomes unreachable. If
ROUTER_B is still considered reachable:
* Ongoing communication instances employing source addresses from
PREFIX_A via ROUTER_A should continue employing ROUTER_A as the
next-hop, since ROUTER_A is the only router advertising PREFIX_A.
* New communication instances should employ addresses from PREFIX_B
via ROUTER_B (as next-hop), since ROUTER_B is the only router
known to be reachable, and PREFIX_B is the only prefix being
advertised by ROUTER_B.
Hosts implementing [RFC8028] will result in ongoing communications
from PREFIX_A via ROUTER_A will continue employing ROUTER_A as the
next-hop. However, [RFC6724] does not take into consideration the
reachability of the next-hop when performing source address
determination, and hence may end up selecting a source address that
would end up employing an unreachable next hop (an address from
PREFIX_A via ROUTER_A as the next hop, in our scenario).
NOTE:
In this scenario, both ROUTER_A and ROUTER_B advertise the same
RNDSS (RDNSS_A), and therefore the information learned from that
DNS server is presumably equally usable from PREFIX_A via ROUTER_A
and from PREFIX_B via ROUTER_B. Hence, if ROUTER_A becomes
unreachable while ROUTER_B is still known to be reachable, hosts
SHOULD prefer using PREFIX_B via ROUTER_B.
In a scenario where ROUTER_A advertised RDNSS_A, and ROUTER_B
advertised RDNSS_B, and ROUTER_A became unreachble, one could
envision the following cases:
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1. Since ROUTER_A is unreachable, RDNSS_A would be unreachable.
Hence RDNSS_B would be employed to resolve domain names, and
as per Section 3.1, connections to IP addresses obtained via
RDNSS_B would employ addresses from PREFIX_B via ROUTER_B.
2. As per Section 3.1, a host should not employ cached DNS
entries obtained via a RDNSS where none the router that
advertised RDNSS_B are known to reachable, since that would
force the host to employ an unreachable router as the next
hop.
3.3. Multi-Router Failover Scenario
Consider the case where two routers attach to the same network
(Network_C), and advertise the same configuration information. That
is,
* Two SLAAC routers (ROUTER_A and ROUTER_B) are attached to
Network_C.
* ROUTER_A advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* ROUTER_B advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* Host C attaches to Network_C, and thus configures:
- One or more addresses from PREFIX_A.
- Two default routers (ROUTER_A and ROUTER_B).
- One recursive DNS server: RDNSS_A.
Consider the case where e.g. ROUTER_A becomes unreachable, while
ROUTER_B is still known to be reachable. If ROUTER_A is still in the
reachable state:
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* Ongoing communication instances currently employing ROUTER_A as
their next-hop should switch to employing ROUTER_B.
* New communication instances should employ ROUTER_B as their next-
hop (since ROUTER_B is known to be reachable, while ROUTER_A is
known to be unreachable).
Existing implementations are expected to handle this scenario
gracefully, since Section 6.3.6 of [RFC4861] required that "Routers
that are reachable or probably reachable (i.e., in any state other
than INCOMPLETE) SHOULD be preferred over routers whose reachability
is unknown or suspect".
3.4. Multi-Interface Scenario
This scenario is similar to the one described in Section 3.1 with the
only difference in that a host is attached to one or more networks
via two or more network interfaces.
NOTE:
In the most common multi-interface case, the host will be attached
to different networks via each network interfaces, and hence the
multi-interface scenario will typically also result in a "multi-
router" and "multiple-prefix" scenario (see Section 2). However,
in the specific corner case where a host employs two network
interfaces two attach to the same local network, this will
essentially result in a Section 3.1 scenario (see Section 2):
while the router available via both interfaces is actually the
same router, from the perspective of the host it can be considered
to be a different router (e.g., they will typically result in two
default routers, each via the corresponding network interface).
Consider a network scenario where a user connects to two different
ISPs (ISP_A and ISP_B), via two different network interfaces (e.g.,
one Ethernet interface and a wireless Wi-Fi interface). The scenario
could be described as follows:
* ROUTER_A from ISP_A is attached to Network_A, and advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* ISP_A enforces ingress filtering [RFC2827], and implements ACLs
such that RDNSS_A only processes requests from ISP_A customers.
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* ROUTER_B from ISP_B is attached to Network_B, and advertises:
- Prefix PREFIX_B for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_B) (by means of Recursive DNS
Server option [RFC8106]).
* ISP_B enforces ingress filtering [RFC2827], and implements ACLs
such that RDNSS_B only processes requests from ISP_B customers.
* Host C attaches to Network_A with one network interface, and to
Network_B with another network interface, and configures:
- Addresses from both prefixes (PREFIX_A and PREFIX_B).
- Two default routers (ROUTER_A and ROUTER_B).
- Two recursive DNS servers: RDNSS_A and RDNSS_B.
In this scenario, Host C may only send traffic from PREFIX_A via
ROUTER_A or from PREFIX_B via ROUTER_B: otherwise, packets will be
dropped as a result of ingress filtering [RFC2827]. Similarly, Host
C may only send DNS queries from PREFIX_A to RDNSS_A, or from
PREFIX_B to RDNSS_B: sending traffic from PREFIX_A to RDNSS_B or from
PREFIX_B to RDNSS_A will resul in the ACLs enforced by the respective
ISPs to drop the DNS queries.
It should be noted that it is quite common for DNS responses to
depend on the source address of the query, for improved service. For
example, if the "www.example.com" web site was served via a Content
Delivery Network (CDN), RDNSS_A would likely resolve that domain name
to an IP address that is topologically close to ISP_A, while RDNSS_B
would resolve the same domain name to an address that is
topologically close to ISP_B. In many cases, the corresponding web
cache might be hosted within the ISP network itself. In these
scenarios, using the information learned from RDNSS_A via ISP_B, or
using the information learned via RDNSS_B via ISP_A would likely lead
to sub-optimal service (e.g., larger Round-Trip Time) or no service
(if ACLs were being enforced).
It should be evident that each piece of information being advertised
via SLAAC is only usable when employed in conjunction with the rest
of the information advertised by the same router. However, SLAAC
does not require this behavior: hosts are free to use any piece of
configuration they learn via SLAAC as they see fit.
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NOTE:
For example, a host implementing the Weak End System (ES) model
(see Section 3.3.4.2 from [RFC1122]) could indeed send e.g.
packets from PREFIX_A via ROUTER_B.
3.5. Conflicting Information
Consider the case where two routers attach to the same network, and
advertise the same configuration information. That is,
* Two SLAAC routers (ROUTER_A and ROUTER_B) are attached to
Network_C
* ROUTER_A advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* ROUTER_B advertises:
- Prefix PREFIX_A for address configuration (by means of a Prefix
Information Option (PIO) [RFC4861]).
- One Recursive DNS server (RDNSS_A) (by means of Recursive DNS
Server option [RFC8106]).
* Host C attaches to Network_C, and thus configures:
- One or more addresses from PREFIX_A.
- Two default routers (ROUTER_A and ROUTER_B).
- One recursive DNS server: RDNSS_A.
Consider the case where e.g. ROUTER_B is unable to refresh its
network configuration information from its upstream, and thus
advertises the same configuration as before, but with a lifetime of
0. That is, it advertises:
* A PIO conveying PREFIX_A with both a Preferred Lifetime and a
Valid Lifetime of 0.
* A RDNSS conveying RDNSS_A with a Lifetime of 0.
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Presumably, this means that according to ROUTER_B, this information
should no longer be used:
* Hosts should remove any configured addresses for such prefixes.
As a result, they should also abort any ongoing TCP connections.
* Hosts should also remove the corresponding RDNSS server from their
list of RDNSS servers.
This would also happen if ROUTER_A was still announcing the same
configuration information with non-zero lifetimes.
It is clear that a more resilient behavior would be to maintain, for
each piece of network configuration information, different timers for
each SLAAC advertising router. Thus, if a SLAAC router advertised
some configuration information with a lifetime of 0, this would
simply mean that such configuration information should be
disassociated with that particular router. Only when configuration
information is no longer associated with any router would the
information be removed from the host altogether.
4. Prior Work
[RFC8028] analyzes the challenge represented by having multiple
default routers when addresses from multiple prefixes are employed.
However, there are a few gaps in the specification:
* Extrapolating RFC 8028 to other network configuration information
(such as Route Information Options (RIOs) [RFC4191] and RDNSS
[RFC8106]), as discussed in Section 3.1 of this document.
* Considering how to aggregate configuration information when the
same information is advertised by multiple routers, with different
timers/lifetime values (as discussed in Section 3.5).
* Considering failure cases, such as those discussed in Section 3.3
and Section 3.2.
5. Future Work
This document describes a number of common network scenarios that are
currently unsupported by IPv6. These scenarios have become more and
more common, as a result of:
* Increased number of home-office users, requiring the use of
multiple upstream ISP for improved resiliency
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* Increased number of mobile users, which may not only connect via
the mobile operator but also via a Wi-Fi connection when
available.
As a result, this document concludes that protocol improvements that
accommodate these deployment scenarios are warranted.
[I-D.gont-6man-multi-ipv6-spec] is a draft protocol specification
that aims to incorporate support for these scearios into IPv6 hosts.
6. IANA Considerations
This document has no actions for IANA.
7. Security Considerations
This document does not introduce any new attack vectors. A host that
were to implement the behavior described in this document might
actually reduce the impact of some Neighbor discovery attacks. For
example, an ND attack meaning to disable an IPv6 prefix by forging a
Router Advertisement (RA) with a PIO for the target prefix with a
zero lifetime would only succeed if:
* the RA impersonates an existing router (i.e., it employs the
address of an existing router as the source address of the RA
packet).
* No other router on the same network segment is currently
advertising the target prefix.
Similarly, in a scenario where a host is employing multiple
interfaces, and an attacker tries to disable the usage of a RDNSS by
sending forged RAs advertising a RDNSS with a zero lifetime, the
attacker would only be able to affect usage of that RDNSS via the
network interface attached to network on which the attacker is
performing the attack. However, RDNSS servers employed via network
interfaces attached to different networks would remain unaffected.
8. Acknowledgments
The authors would like to thank (in alphabetical order) Brian
Carpenter for providing valuable comments on earlier versions of this
document.
Fernando would also like to thank Brian Carpenter who, over the
years, has answered many questions and provided valuable comments
that has benefited his protocol-related work.
9. References
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9.1. Normative References
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989,
<https://www.rfc-editor.org/info/rfc1122>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191,
November 2005, <https://www.rfc-editor.org/info/rfc4191>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<https://www.rfc-editor.org/info/rfc6724>.
[RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by
Hosts in a Multi-Prefix Network", RFC 8028,
DOI 10.17487/RFC8028, November 2016,
<https://www.rfc-editor.org/info/rfc8028>.
[RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration",
RFC 8106, DOI 10.17487/RFC8106, March 2017,
<https://www.rfc-editor.org/info/rfc8106>.
9.2. Informative References
Gont Expires 4 September 2025 [Page 14]
Internet-Draft Problem Statement about Multi-IPv6 Scena March 2025
[I-D.gont-6man-multi-ipv6-spec]
Gont, F., "Improving Support for Multi-Router and Multi-
Prefix IPv6 Networks", Work in Progress, Internet-Draft,
draft-gont-6man-multi-ipv6-spec-00, 2 February 2025,
<https://datatracker.ietf.org/doc/html/draft-gont-6man-
multi-ipv6-spec-00>.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
May 2000, <https://www.rfc-editor.org/info/rfc2827>.
Author's Address
Fernando Gont
SI6 Networks
Segurola y Habana 4310, 7mo Piso
Villa Devoto
Ciudad Autonoma de Buenos Aires
Argentina
Email: fgont@si6networks.com
URI: https://www.si6networks.com
Gont Expires 4 September 2025 [Page 15]