RFC 8111
Locator/ID Separation Protocol Delegated Database Tree (LISP-DDT)
Pages: 44
Experimental
Experimental
Part 2 of 2 – Pages 23 to 44
8. Pseudocode and Decision Tree Diagrams
To illustrate the DDT algorithms described above and to aid in implementation, each of the major DDT Map-Server and DDT Map-Resolver functions are described below, first using simple "pseudocode" and then in the form of a decision tree.8.1. Map-Resolver Processing of ITR Map-Request
8.1.1. Pseudocode Summary
if ( request pending, i.e., (ITR,EID) of request same ) { replace old request with new, & use new request nonce for future requests } else if ( no match in refcache ) { return Negative Map-Reply to ITR } else if ( match type DELEGATION-HOLE ) { return Negative Map-Reply to ITR } else if ( match type MS-ACK ) { fwd DDT Map-Request to Map-Server } else { store & fwd DDT Map-Request w/o security material to node delegation }
8.1.2. Decision Tree Diagram
+------------+ | Is request | Yes | pending? |----> Replace old request with | | new nonce for future requests +------------+ | |No | V +------------+ | Match in | No | referral |----> Send Negative Map-Reply | cache? | (not a likely event, as root or +------------+ hint configured on every Map-Resolver) | |Yes | V +-------------+ | Match type | Yes | DELEGATION- |----> Send Negative Map-Reply | HOLE? | +-------------+ | |No | V +------------+ | Match type | Yes | MS-ACK? |----> Forward DDT Map-Request to Map-Server | | +------------+ | |No | V Store original request & send DDT Map-Request w/o security material to DDT node delegation
8.2. Map-Resolver Processing of Map-Referral Message
8.2.1. Pseudocode Summary
if ( authentication signature validation failed ) { silently drop } if ( no request pending matched by referral nonce ) { silently drop } if ( pfx in referral less specific than last referral used ) { if ( gone through root ) { silently drop } else { send request to root } } switch (map_referral_type) { case NOT_AUTHORITATIVE: if ( gone through root ) { return Negative Map-Reply to ITR } else { send request to root } case DELEGATION_HOLE: cache & send Negative Map-Reply to ITR case MS_REFERRAL: if ( referral equal to last used ) { if ( gone through root ) { return Negative Map-Reply to ITR } else { send request to root } } else { cache follow the referral; include security material }
case NODE_REFERRAL:
if ( referral equal to last used ) {
if ( gone through root ) {
return Negative Map-Reply to ITR
} else {
send request to root
}
} else {
cache
follow the referral; strip security material
}
case MS_ACK:
if ( security material stripped ) {
resend request with security material
if { !incomplete } {
cache
}
}
case MS_NOT_REGISTERED:
if { all Map-Server delegations not tried } {
follow delegations not tried
if ( !incomplete ) {
cache
}
} else {
send Negative Map-Reply to ITR
if { !incomplete } {
cache
}
}
case DEFAULT:
drop
}
}
8.2.2. Decision Tree Diagram
+----------------+ | Auth signature | No | valid? |----> Silently drop +----------------+ | Yes V +------------+ | Is request | No | pending? |----> Silently drop +------------+ | Yes V +------------------------------+ Yes | Pfx less specific than last? |----> Silently drop +------------------------------+ |No V +---------------------------------------------------+ | What is Map-Referral type? |--Unknown-+ +---------------------------------------------------+ | | | | | | | V | | | | | DEL_HOLE Drop | | | | MS_ACK | | | | | | V | | MS_REF NODE_REF | Cache & return | | | | V Negative Map-Reply | | | | +---------+ | NOT_AUTH | | | Was sec | Yes | | | | | material| | | | | |stripped?|----> Done | | V V +---------+ | | +------------+ | No | | Yes | Pfx equal | V MS_NOT_REGISTERED | +---| to last | +------------+ | | | | used? | |"Incomplete"| Yes | | | +------------+ | bit set? |---> Resend DDT | V V |No +------------+ request w/ | +------------+ | |No security | | Gone | V | material | | through | Cache & follow V | | root? | the referral Cache & resend DDT | +------------+ request with | |No |Yes security material | | | | V V
| Send req Send Negative Map-Reply
| to root
V
+-----------+ Yes +------------+ Yes
| Other MS |---Follow other MS-------->|"Incomplete"|----> Don't cache
| not tried?| | bit set? |
| |--Send Negative Map-Reply->| |----> Cache
+-----------+ No +------------+ No
8.3. DDT Node Processing of DDT Map-Request Message
8.3.1. Pseudocode Summary
if ( I am not authoritative ) {
send Map-Referral NOT_AUTHORITATIVE with
"Incomplete" bit set and TTL 0
} else if ( delegation exists ) {
if ( delegated Map-Servers ) {
send Map-Referral MS_REFERRAL with
TTL 'Default_DdtNode_Ttl'
} else {
send Map-Referral NODE_REFERRAL with
TTL 'Default_DdtNode_Ttl'
}
} else {
if ( EID in site) {
if ( site registered ) {
forward Map-Request to ETR
if ( Map-Server peers configured ) {
send Map-Referral MS_ACK with
TTL 'Default_Registered_Ttl'
} else {
send Map-Referral MS_ACK with
TTL 'Default_Registered_Ttl' and "Incomplete" bit set
}
} else {
if ( Map-Server peers configured ) {
send Map-Referral MS_NOT_REGISTERED with
TTL 'Default_Configured_Not_Registered_Ttl'
} else {
send Map-Referral MS_NOT_REGISTERED with
TTL 'Default_Configured_Not_Registered_Ttl'
and "Incomplete" bit set
}
}
} else {
send Map-Referral DELEGATION_HOLE with
TTL 'Default_Negative_Referral_Ttl'
}
}
where architectural constants for TTL are set as follows:
Default_DdtNode_Ttl 1440 minutes
Default_Registered_Ttl 1440 minutes
Default_Negative_Referral_Ttl 15 minutes
Default_Configured_Not_Registered_Ttl 1 minute
8.3.2. Decision Tree Diagram
+------------+ | Am I | No | authori- |----> Return NOT_AUTHORITATIVE | tative? | Incomplete = 1 +------------+ TTL = Default_DdtNode_Ttl | |Yes | V +------------+ +-------------+ | Delegation | Yes | Delegations | Yes | exists? |---->| are |----> Return MS_REFERRAL | | | Map-Servers?| TTL = Default_DdtNode_Ttl +------------+ +-------------+ | \ No |No +--> Return NODE_REFERRAL | TTL = Default_DdtNode_Ttl V +------------+ +------------+ +------------+ | EID in | Yes | Site | Yes | Map-Server | | site |---->| registered?|----> Forward---->| peers | | config? | | | Map-Request | configured?| +------------+ +------------+ to ETR +------------+ | | | | | |No No| |Yes | | | | | | V V | | Return MS_ACK Return MS_ACK | V with INC=1 | +------------+ TTL = Default_Registered_Ttl | | Map-Server | Yes | | peers |----> Return MS_NOT_REGISTERED | | configured?| TTL = Default_Negative_Referral_Ttl | +------------+ | \ No |No +--> Return MS_NOT_REGISTERED | Incomplete = 1 V TTL = Default_Negative_Referral_Ttl Return DELEGATION_HOLE TTL = Default_Negative_Referral_Ttl
9. Example Topology and Request/Referral Following
This section shows an example DDT tree and several possible scenarios of Map-Requests coming to a Map-Resolver and subsequent iterative DDT referrals. In this example, RLOCs of DDT nodes are shown in the IPv4 address space while the EIDs are in the IPv6 AF. The same principle of hierarchical delegation and pinpointing referrals is equally applicable to any AF whose address hierarchy can be expressed as a bit string with associated length. The DDT "tree" of IPv4 prefixes is another AF with immediate practical value. This section could benefit from additional examples, perhaps including one using IPv4 EIDs and another using IPv6 RLOCs. If this document is moved to the Standards Track, consideration should be given to adding such examples.
To show how referrals are followed to find the RLOCs for a number of
EIDs, consider the following example EID topology for DBID=0, IID=0,
AFI=2, and EID=0/0:
+---------------------+ +---------------------+
| root1: 192.0.2.1 | | root2: 192.0.2.2 |
| authoritative: ::/0 | | authoritative: ::/0 |
+---------------------+ +---------------------+
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| | | |
V V V V
+-------------------------+ +--------------------------+
| DDT node1: 192.0.2.11 | | DDT node2: 192.0.2.12 |
| authoritative: | | authoritative: |
| 2001:db8::/32 | | 2001:db8::/32 |
+-------------------------+ +--------------------------+
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| | | |
V V V V
+--------------------------+ +---------------------------+
| Map-Server1: 192.0.2.101 | | DDT node3: 192.0.2.201 |
| authoritative: | | authoritative: |
| 2001:db8:0100::/40 | | 2001:db8:0500::/40 |
| site1: 2001:db8:0103::/48| +---------------------------+
| site2: 2001:db8:0104::/48| | |
+--------------------------+ | |
| |
| |
V V
+---------------------------+ +---------------------------+
| Map-Server2: 192.0.2.211 | | Map-Server3: 192.0.2.221 |
| authoritative: | | authoritative: |
| 2001:db8:0500::/48 | | 2001:db8:0501::/48 |
|site3: 2001:db8:0500:1::/64| |site5: 2001:db8:0501:8::/64|
|site4: 2001:db8:0500:2::/64| |site6: 2001:db8:0501:9::/64|
+---------------------------+ +---------------------------+
DDT nodes are configured for this "root" at IP addresses 192.0.2.1
and 192.0.2.2. DDT Map-Resolvers are configured with default
referral cache entries for these addresses.
The root DDT nodes delegate 2001:db8::/32 to two DDT nodes with IP addresses 192.0.2.11 and 192.0.2.12. The DDT nodes for 2001:db8::/32 delegate 2001:db8:0100::/40 to a DDT Map-Server with RLOC 192.0.2.101. The DDT Map-Server for 2001:db8:0100::/40 is configured to allow ETRs to register the sub-prefixes 2001:db8:0103::/48 and 2001:db8:0104::/48. The DDT nodes for 2001:db8::/32 also delegate 2001:db8:0500::/40 to a DDT node with RLOC 192.0.2.201. The DDT node for 2001:db8:0500::/40 is further configured to delegate 2001:db8:0500::/48 to a DDT Map-Server with RLOC 192.0.2.211 and 2001:db8:0501::/48 to a DDT Map-Server with RLOC 192.0.2.221. The DDT Map-Server for 2001:db8:0500::/48 is configured to allow ETRs to register the sub-prefixes 2001:db8:0500:1::/64 and 2001:db8:0500:2::/64. The DDT Map-Server for 2001:db8:0501::/48 is configured to allow ETRs to register the sub-prefixes 2001:db8:0501:8::/64 and 2001:db8:0501:9::/64.9.1. Lookup of 2001:db8:0103:1::1/128
The first example shows a DDT Map-Resolver following a delegation from the root to a DDT node followed by another delegation to a DDT Map-Server. ITR1 sends an Encapsulated Map-Request for 2001:db8:0103:1::1 to one of its configured (DDT) Map-Resolvers. The DDT Map-Resolver proceeds as follows: 1. Send a DDT Map-Request (for 2001:db8:0103:1::1) to one of the root DDT nodes (192.0.2.1 or 192.0.2.2). 2. Receive (and save in the referral cache) the Map-Referral for EID-prefix 2001:db8::/32, action code NODE-REFERRAL, RLOC set (192.0.2.11, 192.0.2.12). 3. Send a DDT Map-Request to 192.0.2.11 or 192.0.2.12. 4. Receive (and save in the referral cache) the Map-Referral for EID-prefix 2001:db8:0100::/40, action code MS-REFERRAL, RLOC set (192.0.2.101).
5. Send a DDT Map-Request to 192.0.2.101; if the ITR-originated
Encapsulated Map-Request had a LISP-SEC signature, it is
included.
6. The DDT Map-Server at 192.0.2.101 decapsulates the DDT
Map-Request and forwards the Map-Request to a registered site1
ETR for 2001:db8:0103::/48.
7. The DDT Map-Server at 192.0.2.101 sends a Map-Referral message
for EID-prefix 2001:db8:0103::/48, action code MS-ACK, to the DDT
Map-Resolver.
8. The DDT Map-Resolver receives the Map-Referral message and
dequeues the pending request for 2001:db8:0103:1::1.
9. The site1 ETR for 2001:db8:0103::/48 receives the Map-Request
forwarded by the DDT Map-Server and sends a Map-Reply to ITR1.
9.2. Lookup of 2001:db8:0501:8:4::1/128
The next example shows a three-level delegation: root to first DDT
node, first DDT node to second DDT node, and second DDT node to DDT
Map-Server.
ITR2 sends an Encapsulated Map-Request for 2001:db8:0501:8:4::1 to
one of its configured (DDT) Map-Resolvers, which are different from
those for ITR1. The DDT Map-Resolver proceeds as follows:
1. Send a DDT Map-Request (for 2001:db8:0501:8:4::1) to one of the
root DDT nodes (192.0.2.1 or 192.0.2.2).
2. Receive (and save in the referral cache) the Map-Referral for
EID-prefix 2001:db8::/32, action code NODE-REFERRAL, RLOC set
(192.0.2.11, 192.0.2.12).
3. Send a DDT Map-Request to 192.0.2.11 or 192.0.2.12.
4. Receive (and save in the referral cache) the Map-Referral for
EID-prefix 2001:db8:0500::/40, action code NODE-REFERRAL, RLOC
set (192.0.2.201).
5. Send a DDT Map-Request to 192.0.2.201.
6. Receive (and save in the referral cache) the Map-Referral for
EID-prefix 2001:db8:0501::/48, action code MS-REFERRAL, RLOC set
(192.0.2.221).
7. Send a DDT Map-Request to 192.0.2.221; if the ITR-originated
Encapsulated Map-Request had a LISP-SEC signature, it is
included.
8. The DDT Map-Server at 192.0.2.221 decapsulates the DDT
Map-Request and forwards the Map-Request to a registered site5
ETR for 2001:db8:0501:8::/64.
9. The DDT Map-Server at 192.0.2.221 sends a Map-Referral message
for EID-prefix 2001:db8:0501:8::/64, action code MS-ACK, to the
DDT Map-Resolver.
10. The DDT Map-Resolver receives a Map-Referral(MS-ACK) message and
dequeues the pending request for 2001:db8:0501:8:4::1.
11. The site5 ETR for 2001:db8:0501:8::/64 receives a Map-Request
forwarded by the DDT Map-Server and sends a Map-Reply to ITR2.
9.3. Lookup of 2001:db8:0104:2::2/128
This example shows how a DDT Map-Resolver uses a saved referral cache
entry to skip the referral process and go directly to a DDT
Map-Server for a prefix that is similar to one previously requested.
In this case, ITR1 uses the same Map-Resolver used in the example in
Section 9.1. It sends an Encapsulated Map-Request for
2001:db8:0104:2::2 to that (DDT) Map-Resolver. The DDT Map-Resolver
finds an MS-REFERRAL cache entry for 2001:db8:0100::/40 with RLOC set
(192.0.2.101) and proceeds as follows:
1. Send a DDT Map-Request (for 2001:db8:0104:2::2) to 192.0.2.101;
if the ITR-originated Encapsulated Map-Request had a LISP-SEC
signature, it is included.
2. The DDT Map-Server at 192.0.2.101 decapsulates the DDT
Map-Request and forwards the Map-Request to a registered site2
ETR for 2001:db8:0104::/48.
3. The DDT Map-Server at 192.0.2.101 sends a Map-Referral message
for EID-prefix 2001:db8:0104::/48, action code MS-ACK, to the DDT
Map-Resolver.
4. The DDT Map-Resolver receives the Map-Referral (MS-ACK) and
dequeues the pending request for 2001:db8:0104:2::2.
5. The site2 ETR for 2001:db8:0104::/48 receives a Map-Request and
sends a Map-Reply to ITR1.
9.4. Lookup of 2001:db8:0500:2:4::1/128
This example shows how a DDT Map-Resolver uses a saved referral cache entry to start the referral process at a non-root, intermediate DDT node for a prefix that is similar to one previously requested. In this case, ITR2 uses the same Map-Resolver used in the example in Section 9.2. It sends an Encapsulated Map-Request for 2001:db8:0500:2:4::1 to that (DDT) Map-Resolver, which finds a NODE-REFERRAL cache entry for 2001:db8:0500::/40 with RLOC set (192.0.2.201). It proceeds as follows: 1. Send a DDT Map-Request (for 2001:db8:0500:2:4::1) to 192.0.2.201. 2. Receive (and save in the referral cache) the Map-Referral for EID-prefix 2001:db8:0500::/48, action code MS-REFERRAL, RLOC set (192.0.2.211). 3. Send a DDT Map-Request to 192.0.2.211; if the ITR-originated Encapsulated Map-Request had a LISP-SEC signature, it is included. 4. The DDT Map-Server at 192.0.2.211 decapsulates the DDT Map-Request and forwards the Map-Request to a registered site4 ETR for 2001:db8:0500:2::/64. 5. The DDT Map-Server at 192.0.2.211 sends a Map-Referral message for EID-prefix 2001:db8:0500:2::/64, action code MS-ACK, to the DDT Map-Resolver. 6. The DDT Map-Resolver receives the Map-Referral (MS-ACK) and dequeues the pending request for 2001:db8:0500:2:4::1. 7. The site4 ETR for 2001:db8:0500:2::/64 receives a Map-Request and sends a Map-Reply to ITR2.
9.5. Lookup of 2001:db8:0500::1/128 (Nonexistent EID)
This example uses the cached MS-REFERRAL for 2001:db8:0500::/48 learned above to start the lookup process at the DDT Map-Server at 192.0.2.211. The DDT Map-Resolver proceeds as follows: 1. Send a DDT Map-Request (for 2001:db8:0500::1) to 192.0.2.211; if the ITR-originated Encapsulated Map-Request had a LISP-SEC signature, it is included. 2. The DDT Map-Server at 192.0.2.211, which is authoritative for 2001:db8:0500::/48, does not have a matching delegation for 2001:db8:0500::1. It responds with a Map-Referral message for 2001:db8:0500::/64, action code DELEGATION-HOLE, to the DDT Map-Resolver. The prefix 2001:db8:0500::/64 is used because it is the least-specific prefix that does match the requested EID but does not match one of the configured delegations (2001:db8:0500:1::/64 and 2001:db8:0500:2::/64). 3. The DDT Map-Resolver receives the delegation, adds a negative referral cache entry for 2001:db8:0500::/64, dequeues the pending request for 2001:db8:0500::1, and returns a Negative Map-Reply to ITR2.10. Securing the Database and Message Exchanges
This section specifies the DDT security architecture that provides data origin authentication, data integrity protection, and XEID-prefix delegation. Global XEID-prefix authorization is out of scope for this document. Each DDT node is configured with one or more public/private key pairs that are used to digitally sign Map-Referral Records for XEID-prefix(es) for which the DDT node is authoritative. In other words, each public/private key pair is associated with the combination of a DDT node and an XEID-prefix for which it is authoritative. Every DDT node is also configured with the public keys of its child DDT nodes. By including the public keys of target child DDT nodes in the Map-Referral Records and signing each Record with the DDT node's private key, a DDT node can securely delegate sub-prefixes of its authoritative XEID-prefixes to its child DDT nodes. A DDT node configured to provide hints must also have the public keys of the DDT nodes to which its hints point. DDT node keys can be encoded using LCAF Type 11 to associate the key to the RLOC of the referred DDT node. If a node has more than one public key, it should sign its Records with at least one of these keys. When a node has N keys, it can sustain up to N-1 key compromises. The revocation mechanism is described in Section 10.2.1.
Map-Resolvers are configured with one or more trusted public keys, referred to as "trust anchors". Trust anchors are used to authenticate the DDT security infrastructure. Map-Resolvers can discover a DDT node's public key by either (1) having it configured as a trust anchor or (2) obtaining it from the node's parent as part of a signed Map-Referral. When a public key is obtained from a node's parent, it is considered trusted if it is signed by a trust anchor or if it is signed by a key that was previously trusted. Typically, in a Map-Resolver, the root DDT node's public keys should be configured as trust anchors. Once a Map-Resolver authenticates a public key, it locally caches the key along with the associated DDT node RLOC and XEID-prefix for future use.10.1. XEID-Prefix Delegation
In order to delegate XEID sub-prefixes to its child DDT nodes, a parent DDT node signs its Map-Referrals. Every signed Map-Referral MUST also include the public keys associated with each child DDT node. Such a signature indicates that the parent DDT node is delegating the specified XEID-prefix to a given child DDT node. The signature is also authenticating the public keys associated with the child DDT nodes, and authorizing them to be used by the child DDT nodes, to provide origin authentication and integrity protection for further delegations and mapping information of the XEID-prefix allocated to the DDT node. As a result, for a given XEID-prefix, a Map-Resolver can form an authentication chain from a configured trust anchor (typically the root DDT node) to the leaf nodes (Map-Servers). Map-Resolvers leverage this authentication chain to verify the Map-Referral signatures while walking the DDT tree until they reach a Map-Server authoritative for the given XEID-prefix.10.2. DDT Node Operation
Upon receiving a Map-Request, the DDT node responds with a Map-Referral as specified in Section 7. For every Record present in the Map-Referral, the DDT node also includes the public keys associated with the Record's XEID-prefix and the RLOCs of the child DDT nodes. Each Record contained in the Map-Referral is signed using the DDT node's private key.10.2.1. DDT Public Key Revocation
The node that owns a public key can also revoke that public key. For instance, if a parent DDT node advertises a public key for one of its child DDT nodes, the child DDT node can at a later time revoke that key. Since DDT nodes do not keep track of the Map-Resolvers that
query them, revocation is done in a pull model, where the Map-Resolver is informed of the revocation of a key only when it queries the node that owns that key. If the parent DDT node is configured to advertise that key, the parent DDT node must also be signaled to remove the key from the Records it advertises for the child DDT node; this is necessary to avoid further distribution of the revoked key. To securely revoke a key, the DDT node creates a new Record for the associated XEID-prefix and locator, including the revoked key with the R bit set. (See Section 4.7 of [RFC8060] for details regarding the R bit.) The DDT node must also include a signature in the Record that covers this Record; this is computed using the private key corresponding to the key being revoked. Such a Record is termed a "revocation record". By including this Record in its Map-Referrals, the DDT node informs querying Map-Resolvers about the revoked key. A digital signature computed with a revoked key can only be used to authenticate the revocation and SHOULD NOT be used to validate any data. To prevent a compromised key from revoking other valid keys, a given key can only be used to sign a revocation for that specific key; it cannot be used to revoke other keys. This prevents the use of a compromised key to revoke other valid keys as described in [RFC5011]. A revocation record MUST be advertised for a period of time equal to or greater than the TTL value of the Record that initially advertised the key, starting from the time that the advertisement of the key was stopped by removal from the parent DDT node.10.3. Map-Server Operation
Similar to a DDT node, a Map-Server is configured with one or more public/private key pairs that it must use to sign Map-Referrals. However, unlike DDT nodes, Map-Servers do not delegate prefixes and as a result do not need to include keys in the Map-Referrals they generate.10.4. Map-Resolver Operation
Upon receiving a Map-Referral, the Map-Resolver MUST first verify the signature(s) by using either a trust anchor or a previously authenticated public key associated with the DDT node sending the Map-Referral. If multiple authenticated keys are associated with the DDT node sending this Map-Referral, the Key Tag field (Section 6.4.1) of the signature can be used to select the correct public key for verifying the signature. If the key tag matches more than one key associated with that DDT node, the Map-Resolver MUST try to verify the signature with all matching keys. For every matching key that is
found, the Map-Resolver MUST also verify that the key is authoritative for the XEID-prefix in the Map-Referral Record. If such a key is found, the Map-Resolver MUST use it to verify the associated signature in the Record. If (1) no matching key is found, (2) none of the matching keys is authoritative for the XEID-prefix in the Map-Referral Record, or (3) such a key is found but the signature is not valid, the Map-Referral Record is considered corrupted and MUST be discarded. This may be due to expired keys. The Map-Resolver MAY try other siblings of this node if there is an alternate node that is authoritative for the same prefix. If not, the Map-Resolver CAN query the DDT node's parent to retrieve a valid key. It is good practice to use a counter or timer to avoid repeating this process if the Map-Resolver cannot verify the signature after several attempts. Once the signature is verified, the Map-Resolver has verified the XEID-prefix delegation in the Map-Referral. This also means that public keys of the child DDT nodes were authenticated; the Map-Resolver must add these keys to the authenticated keys associated with each child DDT node and XEID-prefix. These keys are considered valid for the duration specified in the Record's TTL field.11. Open Issues and Considerations
There are a number of issues with the organization of the mapping database that need further investigation. Among these are: o Defining an interface to implement interconnection and/or interoperability with other mapping databases, such as LISP+ALT. o Additional key structures for use with LISP-DDT, such as key structures to support additional EID formats as defined in [RFC8060]. o Management of the DDT Map-Resolver referral cache -- in particular, detecting and removing outdated entries. o Best practices for either configuring hint referrals or avoiding their use. Operational experience will help answer open questions surrounding these and other issues.
12. IANA Considerations
IANA has made the following early assignment per this document: o Message type 6, "LISP DDT Map-Referral", was added to the "LISP Packet Types" registry. See Section 6.4 ("Map-Referral Message Format"). As this document is an Experimental RFC, this is an early allocation as per [RFC7120].13. Security Considerations
Section 10 describes a DDT security architecture that provides data origin authentication, data integrity protection, and XEID-prefix delegation within the DDT infrastructure. Global XEID-prefix authorization is beyond the scope of this document, but the Secure Inter-Domain Routing (SIDR) working group [RFC6480] is developing an infrastructure to support improved security of Internet routing. Further work is required to determine if SIDR's Public Key Infrastructure (PKI) and the distributed repository system it uses for storing and disseminating PKI data objects may also be used by DDT devices to verifiably assert that they are the legitimate holders of a set of XEID-prefixes. This document specifies how DDT security and LISP-SEC [LISP-SEC] complement one another to secure the DDT infrastructure, Map-Referral messages, and the Map-Request/Map-Reply protocols. In the future, other LISP security mechanisms may be developed to replace LISP-SEC. Such future security mechanisms should describe how they can be used together with LISP-DDT to provide similar levels of protection. LISP-SEC can use the DDT public-key infrastructure to secure the transport of LISP-SEC key material (the One-Time Key) from a Map-Resolver to the corresponding Map-Server. For this reason, when LISP-SEC is deployed in conjunction with a LISP-DDT mapping database and the path between the Map-Resolver and Map-Server needs to be protected, DDT security as described in Section 10 should be enabled as well.
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The Locator/ID Separation Protocol (LISP)", RFC 6830, DOI 10.17487/RFC6830, January 2013, <http://www.rfc-editor.org/info/rfc6830>. [RFC6833] Fuller, V. and D. Farinacci, "Locator/ID Separation Protocol (LISP) Map-Server Interface", RFC 6833, DOI 10.17487/RFC6833, January 2013, <http://www.rfc-editor.org/info/rfc6833>. [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January 2014, <http://www.rfc-editor.org/info/rfc7120>. [RFC8017] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch, "PKCS #1: RSA Cryptography Specifications Version 2.2", RFC 8017, DOI 10.17487/RFC8017, November 2016, <http://www.rfc-editor.org/info/rfc8017>. [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, February 2017, <http://www.rfc-editor.org/info/rfc8060>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <http://www.rfc-editor.org/info/rfc8174>.
14.2. Informative References
[AFI] IANA, "Address Family Numbers", <http://www.iana.org/assignments/address-family-numbers/>. [LISP-SEC] Maino, F., Ermagan, V., Cabellos, A., and D. Saucez, "LISP-Security (LISP-SEC)", Work in Progress, draft-ietf-lisp-sec-12, November 2016. [LISP-TREE] Jakab, L., Cabellos-Aparicio, A., Coras, F., Saucez, D., and O. Bonaventure, "LISP-TREE: a DNS Hierarchy to Support the LISP Mapping System", IEEE Journal on Selected Areas in Communications, Volume 28, Issue 8, DOI 10.1109/JSAC.2010.101011, September 2010, <http://ieeexplore.ieee.org/xpls/ abs_all.jsp?arnumber=5586446>. [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, <http://www.rfc-editor.org/info/rfc1918>. [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) Trust Anchors", STD 74, RFC 5011, DOI 10.17487/RFC5011, September 2007, <http://www.rfc-editor.org/info/rfc5011>. [RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480, February 2012, <http://www.rfc-editor.org/info/rfc6480>. [RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, "Locator/ID Separation Protocol Alternative Logical Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836, January 2013, <http://www.rfc-editor.org/info/rfc6836>. [RFC6837] Lear, E., "NERD: A Not-so-novel Endpoint ID (EID) to Routing Locator (RLOC) Database", RFC 6837, DOI 10.17487/RFC6837, January 2013, <http://www.rfc-editor.org/info/rfc6837>.
Acknowledgments
The authors would like to express their thanks to Lorand Jakab, Albert Cabellos, Florin Coras, Damien Saucez, and Olivier Bonaventure for their work on LISP-TREE [LISP-TREE] and LISP iterable mappings that inspired the hierarchical database structure and lookup iteration approach described in this document. Thanks also go to Dino Farinacci and Isidor Kouvelas for their implementation work; to Selina Heimlich and Srin Subramanian for testing; to Fabio Maino for work on security processing; and to Job Snijders, Glen Wiley, Neel Goyal, and Mike Gibbs for work on operational considerations and initial deployment of a prototype database infrastructure. Special thanks go to Jesper Skriver, Andrew Partan, and Noel Chiappa, all of whom have participated in (and put up with) seemingly endless hours of discussion of mapping database ideas, concepts, and issues.Authors' Addresses
Vince Fuller VAF.NET Internet Consulting Email: vince.fuller@gmail.com Darrel Lewis Cisco Systems Email: darlewis@cisco.com Vina Ermagan Cisco Systems Email: vermagan@cisco.com Amit Jain Juniper Networks Email: atjain@juniper.net Anton Smirnov Cisco Systems Email: as@cisco.com