draft-ietf-ipngwg-scoped-routing-02.txt   draft-ietf-ipngwg-scoped-routing-03.txt 
IPNGWG Working Group B. Haberman IPNGWG Working Group B. Haberman
Internet Draft Nortel Networks Internet Draft Nortel Networks
draft-ietf-ipngwg-scoped-routing-02.txt draft-ietf-ipngwg-scoped-routing-03.txt
November 1999 February 2000
Expires August 2000
Routing of Scoped Addresses Routing of Scoped Addresses
in the Internet Protocol Version 6 (IPv6) in the Internet Protocol Version 6 (IPv6)
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026. provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups Force (IETF), its areas, and its working groups. Note that other groups
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http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
This document outlines a mechanism for generating forwarding tables This document outlines a mechanism for generating forwarding tables
that include scoped IPv6 addresses. It defines a set of rules for that include scoped IPv6 addresses. It defines a set of rules for
routers to implement in order to forward packets addressed to scoped routers to implement in order to forward packets addressed to scoped
unicast or multicast addresses regardless of the routing protocol. unicast or multicast addresses regardless of the routing protocol.
These rules apply to all scoped addresses. These rules apply to all scoped addresses.
1. 1. Introduction
Introduction
This document defines a set of rules for the generation of forwarding This document defines a set of rules for the generation of forwarding
table entries for scoped addresses. These rules will describe the table entries for scoped addresses. These rules will describe the
handling of scoped addresses for both single site and site boundary handling of scoped addresses for both single site and site boundary
routers. These rules apply to all routing protocols that support IPv6 routers. These rules apply to all routing protocols that support IPv6
addresses. addresses.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119]. document are to be interpreted as described in [RFC 2119].
2. 2. Assumptions and Definitions
Assumptions and Definitions
This document makes several assumptions concerning sites: This document makes several assumptions concerning sites:
- Links belong to at most one site - Links belong to at most one site
- Interfaces belong to the site of the attached link, if any - Interfaces belong to the site of the attached link, if any
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- Nodes are a part of all sites which their interfaces belong to, - Nodes are a part of all sites which their interfaces belong to,
and no other sites and no other sites
- Site boundaries are identical for unicast and multicast traffic - Site boundaries are identical for unicast and multicast traffic
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| Router | | Router |
******************* ******************* ******************* *******************
| * * | | * * |
Site ID = Y -i/f 3 * * i/f 4- Site ID = Default Site ID = Y -i/f 3 * * i/f 4- Site ID = Default
| * * | | * * |
******************* ******************* ******************* *******************
+-------------------+ +-------------------+
Figure 1: Multi-Sited Router Figure 1: Multi-Sited Router
3. 3. Single Site Routing
Single Site Routing
In a single site router, a routing protocol can advertise and route all In a single site router, a routing protocol can advertise and route all
addresses and prefixes, except the link-local prefixes, on all addresses and prefixes, except the link-local prefixes, on all
interfaces. This configuration does not require any special handling interfaces. This configuration does not require any special handling
for site local addresses. The reception and transmission of site local for site local addresses. The reception and transmission of site local
addresses is handled in the same manner as globally scoped addresses. addresses is handled in the same manner as globally scoped addresses.
This applies to both unicast and multicast routing protocols. This applies to both unicast and multicast routing protocols.
4. 4. Site Boundary Unicast Routing
Site Boundary Unicast Routing
With respect to site boundaries, routers must consider which interfaces With respect to site boundaries, routers must consider which interfaces
a packet can be transmitted on as well as control the propagation of a packet can be transmitted on as well as control the propagation of
routing information specific to the site. This includes controlling routing information specific to the site. This includes controlling
which prefixes can be advertised on an interface. which prefixes can be advertised on an interface.
4.1 Routing Protocols 4.1 Routing Protocols
When a routing protocol determines that it is a site boundary router, When a routing protocol determines that it is a site boundary router,
it must perform additional work in order to protect inter site it must perform additional work in order to protect inter site
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- Lookup outgoing interface's site identifier - Lookup outgoing interface's site identifier
- Compare inbound and outbound interfaces' site identifiers - Compare inbound and outbound interfaces' site identifiers
If the site identifiers match, the packet can be forwarded. If they do If the site identifiers match, the packet can be forwarded. If they do
not match, an ICMPv6 destination unreachable message must be sent to not match, an ICMPv6 destination unreachable message must be sent to
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the sender with a code value, code = 2 (beyond scope of source the sender with a code value, code = 2 (beyond scope of source
address). address).
5. 5. Scoped Multicast Routing
Scoped Multicast Routing
With IPv6 multicast, there are multiple scopes supported. Multicast With IPv6 multicast, there are multiple scopes supported. Multicast
routers must be able to control the propagation of scoped packets based routers must be able to control the propagation of scoped packets based
on administratively configured boundaries. on administratively configured boundaries.
5.1 Routing Protocols 5.1 Routing Protocols
Multicast routing protocols must follow the same rules as the unicast Multicast routing protocols must follow the same rules as the unicast
protocols. They will be required to maintain information about global protocols. They will be required to maintain information about global
prefixes as well as information about all scope boundaries that exist prefixes as well as information about all scope boundaries that exist
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currently in place for global IPv6 multicast. The remaining currently in place for global IPv6 multicast. The remaining
combinations should result in the router performing the same combinations should result in the router performing the same
identifiers check as outlined for the site local unicast addresses. identifiers check as outlined for the site local unicast addresses.
Since IPv6 multicast supports fifteen unique multicast scopes, it is Since IPv6 multicast supports fifteen unique multicast scopes, it is
assumed that scopes 0x1 through 0x4 are strictly less than the unicast assumed that scopes 0x1 through 0x4 are strictly less than the unicast
site scope, scope 0x5 (site) is equal to the unicast site scope, scopes site scope, scope 0x5 (site) is equal to the unicast site scope, scopes
0x6 through 0xd are strictly greater than the unicast site scope and 0x6 through 0xd are strictly greater than the unicast site scope and
strictly less than the unicast global scope, and scope 0xe is equal to strictly less than the unicast global scope, and scope 0xe is equal to
the unicast global scope. the unicast global scope.
6. 6. Protocol Impact
Protocol Impact
The performance impact on routing protocols is obvious. Routers The performance impact on routing protocols is obvious. Routers
implementing scoped address support will be forced to perform an implementing scoped address support will be forced to perform an
additional check in the main forwarding path to determine if the source additional check in the main forwarding path to determine if the source
address is a site-local address. This will add overhead to the address is a site-local address. This will add overhead to the
processing of every packet flowing through the router. In addition, processing of every packet flowing through the router. This overhead
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there will be some storage overhead for the scope identifiers. If is no different than the overhead occurred in checking for invalid
scoped addresses are going to be realized, this performance impact may source addresses such as multicast addresses, the loopback address, and
be acceptable. the unspecified address, which is a required function in IPv6. In
addition, there will be storage overhead for the scope identifiers and
the forwarding tables that must be maintained for each site.
7. 7. Security Considerations
Security Considerations
This document specifies a set of guidelines that allow routers to This document specifies a set of guidelines that allow routers to
prevent site-specific information from leaking out of each site. If prevent site-specific information from leaking out of each site. If
site boundary routers allow site routing information to be forwarded site boundary routers allow site routing information to be forwarded
outside of the site, the integrity of the site could be compromised. outside of the site, the integrity of the site could be compromised.
8. 8. References
References
[RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate [RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP14, March 1999. Requirement Levels", RFC 2119, BCP14, March 1999.
Acknowledgements Acknowledgements
The author would like to thank Thomas Narten, Steve Deering, Erik The author would like to thank Thomas Narten, Steve Deering, Erik
Nordmark, and Matt Crawford for their comments and reviews of this Nordmark, Matt Crawford, and Jim Bound for their comments and reviews of
document. this document.
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Author's Address Author's Address
Brian Haberman Brian Haberman
Nortel Networks Nortel Networks
4309 Emperor Blvd. 4309 Emperor Blvd.
Suite 200 Suite 200
Durham, NC 27703 Durham, NC 27703
1-919-992-4439 1-919-992-4439
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