Network2/Dynamics

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Prerequisite concepts: bandwidth, latency, jitter, availability, model, unicast, multicast, broadcast, network stack

First, some baseline analysis:

Suppose we have a wireless link with capacity C.
Suppose we have N nodes.
Suppose each node n wants to maintain f(n) connections.
If f(n) = 1 then we could allocate up to C/N per connection.
If f(n) = N then we could allocate up to C/N^2 per connection.

Instructive values: C=30 Mbps, N=40, f(n)=N ==> 19 Kbps / conn. Conclusion: beware O(N^2) behavior.

Several important numbers that we need to predict and to measure include bandwidth and latency figures:

tx == transmit, rx == receive, btx == broadcast

btx/tx/rx - ICMPv6+IPv6+phys           - router discovery (RD)
btx/rx    - ICMPv6+IPv6+phys           - duplicate address detection (DAD)
tx/rx     - ICMPv6+IPv6+phys           - NS neighbor discovery (ND)
tx/rx     - UDP+IPv6+phys              - DNS query
tx/rx     - JSON+SSH+TCP+IPv6+phys     - DNS update

where "phys" describes the equations' dependence on the "physical" layer's 
frame overhead and MTU

notable "phys" layers:

Ethernet           -- ad-hoc wifi, infra wifi, 802.11s mesh, switch, hub
TLS+UDP+IPv4       -- openvpn
L2TP+IPsec+IPv4    -- raccoon, isakmpd, openswan, etc.
UDP+IPv4           -- teredo

Baseline overheads:

Ethernet: 18
IPv4: 20 + options
IPv6: 40 + options
ICMPv6: 4
ICMPv6 RA: 16 + prefix+{32} + mtu?{8} 
UDP: 4
TCP: 20 + options?
TLS: 5 + mac?{16,20,32} + pad?{4,8,16}
D-Bus: 12 + type-array
XMPP MUC: 50 + jids
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