diff options
Diffstat (limited to 'draft-schanzen-r5n.xml')
| -rw-r--r-- | draft-schanzen-r5n.xml | 49 |
1 files changed, 26 insertions, 23 deletions
diff --git a/draft-schanzen-r5n.xml b/draft-schanzen-r5n.xml index 4fbfd79..db465f7 100644 --- a/draft-schanzen-r5n.xml +++ b/draft-schanzen-r5n.xml @@ -671,12 +671,24 @@ Connectivity | |Underlay| |Underlay| <t> The routing table consists of an array of lists of connected peers. The i-th list stores neighbours whose identifiers are between - distance 2^i 2^(i+1) from the local peer. - An implementation <bcp14>MAY</bcp14> choose an upper limit on the length of the - lists, but <bcp14>SHOULD</bcp14> try to keep at least 5 entries per bucket. - For example, in case of system constraints with respect to active - connections, an implementation <bcp14>SHOULD</bcp14> evict peers in large buckets - rather than peers from shallow ones. + distance 2^i and 2^(i+1) from the local peer. + System constraints will typically force an implementation to impose some + upper limit on the number of neighbours kept per k-bucket. + </t> + <t> + Implementations <bcp14>SHOULD</bcp14> try to keep at least + 5 entries per k-bucket. Embedded systems that cannot manage + this number of connections <bcp14>MAY</bcp14> use connection-level + signalling to indicate that they are merely a client utilizing a + DHT and not able to participate in routing. DHT peers receiving + such connections <bcp14>MUST NOT</bcp14> include connections to + such restricted systems when making routing decisions. + <t> + If a system hits constraints with respect to + the number of active connections, an implementation + <bcp14>MUST</bcp14> evict peers from those k-buckets with the + largest number of peers. The eviction strategy <bcp14>MUST</bcp14> be + to drop the shortest-lived connections first. </t> <t> As the message traverses a random path through the network for the @@ -1309,7 +1321,7 @@ Connectivity | |Underlay| |Underlay| The payload <bcp14>MUST</bcp14> be considered for the local routing table by trying to establish a connection to the peer using the information from the HELLO block. If a connection can be established, - the peer is added to the <tt>KBuckets</tt> routing table. + the peer is added to the k-buckets of the routing table. </li> <li> If the sender peer of the message is already found in the @@ -1322,7 +1334,7 @@ Connectivity | |Underlay| |Underlay| are validated against the requested BTYPE using the respective block type implementation of <tt>ValidateBlockReply</tt>. If the approximate flag is set and the BTYPE allows the - implementation to compute the key from the block it must match + implementation to compute the key from the block it must match the QUERY_HASH. If the XQUERY is malformed, the message <bcp14>MUST</bcp14> be discarded. <!-- FIXME: This should be reviewed. <= approximate flag --> @@ -1689,21 +1701,12 @@ gnunet+tcp://12.3.4.5/ \ does not have/require a trust anchor a priori. This is (again) in contrast to RELOAD --> <t> - An implementation <bcp14>MAY</bcp14> limit the number the number of neighbours - it stores is any k-bucket of the routing table. - However, the lower bound <bcp14>MUST</bcp14> be adhered to. <!-- FIXME define somewhere--> - If there is a limit to the maximum number of neighbours in a - k-bucket, the implementation must be careful when choosing the - which peers to replace: - For example, a simple optimization of the peer selection algorithm may - be to oder all peers within the k-bucket by distance and evict the - peers which are the farthest away. - However, this is not a good idea from a resilience perspective. - It is much more important to preserve older connections than closer - ones. - Preferring long-term connections over close connections makes it more - difficult for an attacker to execute a Sibyl attack as more resources - need to be invested over time. + If an upper bound to the maximum number of neighbours in a + k-bucket is reached, the implementation <bcp14>MUST</bcp14> + prefer to preserve the oldest working connections instead of + new connections. This makes Sybil attacks less effective + as an adversary would have to invest more resources over time + to mount an effective attack. </t> </section> <section anchor="iana" numbered="true" toc="default"> |