CSC 718 Cheat Sheet

End-to-end & routing

End-to-End: put important jobs at the endpoints; network help is only a speed bonus.
Middleboxes: NAT (state, breaks direct addressing), firewall (can't see app semantics/encryption), DPI (heavy per-conversation cost, blind to TLS).
IGP inside an AS (OSPF/IS-IS); BGP between ASes (path-vector, TCP 179).
BGP selection: LOCAL_PREF, AS_PATH, origin, MED, eBGP>iBGP, IGP metric, router ID.
RPKI/ROA prove origin ownership (not the whole path); MANRS filters routes.
MPLS (labels, LSP, QoS, rigid/costly) vs SD-WAN (IPsec tunnels, central control, cheap/best-effort).

AIMD; Tahoe resets, Reno halves; Cubic uses a cubic curve.
Bufferbloat: d_q = q / C; big buffers add delay not speed.
CoDel: drop early if sojourn > 5 ms for 100 ms.
BBR: BDP = BtlBw x RTprop; keep ~1 BDP in flight (full pipe, empty queue).
QUIC/HTTP3: over UDP, independent streams (no HOL blocking), TLS 1.3 built in, 0/1-RTT.

SDN: control plane out of the box; OpenFlow flow tables; NFV = software appliances; P4 programs the data plane.
Anycast: one IP, many servers, nearest wins; unicast: one IP one machine.
Edge caching: reactive (pull, after request) vs proactive (push, predicted).
6LoWPAN compresses 40 B IPv6 header to a few bytes; RPL builds a DODAG tree (local repair).
MQTT (broker pub/sub), CoAP (HTTP over UDP).