Nokia SRA Composite cheat sheet

GPON downstream uses 1490 nm for data and 1550 nm for RF video overlay; upstream uses 1310 nm. XGS-PON shares the same outside plant and adds 1270 nm upstream with 10G/10G symmetric rates.

GPON split ratios: 1:32 typical, 1:64 max; budget class B+ is 28 dB, class C+ is 32 dB. Power budget = Tx power − receiver sensitivity − connector/splice losses − splitter loss.

Splitter loss ≈ 10·log10(N) + excess loss; a 1:32 splitter is about 15 dB plus 0.5–1 dB excess, so 1:64 adds roughly 3 dB.

ONT ranging in GPON uses equalization delay so all ONTs appear at equal logical distance; upstream bursts are separated by guard bands to avoid collisions.

VDSL2 vectoring cancels far-end crosstalk across bonded lines in the same binder; G.fast extends copper to 106 MHz/212 MHz with typical loop lengths under 250 m.

FTTH architectures: point-to-point (home run), active Ethernet (curb switch), and PON (passive split). PON minimizes fiber count and active elements in the field.

DSL line rate depends on loop length, gauge, and noise margin; raising target SNR margin by 3 dB typically reduces attainable rate by roughly 10–15%.

Ethernet OAM (Y.1731) provides continuity check, loopback, and delay/loss measurement; CFM maintenance domains are bounded by MEPs at domain edges.

5G NR numerologies: subcarrier spacing 15·2^μ kHz; slot length = 1 ms / 2^μ. FR1 is 410 MHz–7.125 GHz, FR2 is 24.25–71 GHz.

RAN split: CU handles RRC/SDAP/PDCP; DU handles RLC/MAC/high-PHY; RU handles low-PHY and RF. F1 is the CU–DU interface, E1 is CU-CP to CU-UP.

NSA (EN-DC) anchors LTE control plane and adds NR user plane; SA uses 5GC with NR as the sole RAT and enables network slicing and URLLC.

5G core SBA: AMF (access/mobility), SMF (session), UPF (user plane), AUSF/UDM (auth and subscription), PCF (policy), NRF (service registry), NSSF (slice selection).

Handover types: Xn-based (direct gNB–gNB), N2-based (via AMF), and inter-RAT. Measurement events A1–A6 govern NR intra/inter-frequency triggers.

Massive MIMO beamforming: 64T64R typical for mid-band; beam management uses SSB beams for initial access and CSI-RS beams for traffic.

QoS in 5G uses 5QI values mapped to QoS flows; GBR flows reserve resources, non-GBR are best effort; reflective QoS mirrors DSCP-like markings.

Network slicing combines S-NSSAI, dedicated UPF placement, and RAN resource partitioning; slice isolation is logical, not physically separate hardware.

OTN hierarchy: ODU0 (1.25G), ODU1 (2.5G), ODU2 (10G), ODU2e (10G LAN), ODU3 (40G), ODU4 (100G); OTU adds FEC and framing overhead.

OTN FEC: GFEC (RS(255,239), ~6.2 dB coding gain), EFEC (~8–9 dB), and oFEC for 400G; FEC choice trades gain against line rate overhead.

SDH/SONET: STM-1 = 155.52 Mbit/s, STM-4 = 622.08, STM-16 = 2.488 Gbit/s, STM-64 = 9.953 Gbit/s; VC-4 payload is 149.76 Mbit/s.

Protection: 1+1 (permanent bridge, hitless), 1:1 (standby, may carry extra traffic), MSP ring with 50 ms switch target; G.8032 ERPS provides sub-50 ms Ethernet ring protection.

FlexE decouples Ethernet MAC rate from PHY rate via bonding and sub-rating; it underpins 400G transport and supports hard client isolation.

Timing: SyncE distributes frequency over Ethernet PHY; IEEE 1588 PTP provides phase/time; class B/C/D clocks define holdover and accuracy grades.

WDM: CWDM uses 20 nm spacing over 1270–1610 nm (18 channels); DWDM uses 50 or 100 GHz grid on C-band (1530–1565 nm), with 80–96 channels at 50 GHz.

ROADM: CD (colorless/directionless), CDC adds contentionless, and C+L band expansion doubles capacity. OSNR budget = launch power − noise floor − span losses.

IPv4 header is 20 bytes minimum; TTL decrements per hop; fragmentation uses identification, flags, and fragment offset. IPv6 header is fixed 40 bytes with extension headers.

Subnetting: usable hosts = 2^(32−prefix) − 2 for /1–/30; /31 is point-to-point (RFC 3021), /32 is a host route.

OSPF uses link-state LSAs and Dijkstra SPF; areas reduce flooding, area 0 is backbone, and virtual links extend area 0 through non-backbone areas.

BGP best-path order: highest weight, highest local preference, locally originated, shortest AS path, lowest origin, lowest MED, eBGP over iBGP, lowest router ID.

MPLS: label stack operations push/swap/pop; LDP distributes labels for IGP routes; RSVP-TE or SR-TE provides traffic engineering. Segment Routing uses SID lists without per-flow state.

MPLS L3VPN uses VRF, RD (route distinguisher), and RT (route target) to isolate and import/export routes across PE routers.

Optical impairments: CD (chromatic dispersion), PMD, OSNR, and nonlinear effects (SPM, XPM, FWM). Coherent DSP compensates CD/PMD electronically.

400G ZR/ZR+ uses oFEC and QPSK/16QAM to reach 80–120 km in pluggable optics; 800G uses 8×100G or 4×200G lanes over shorter spans.

IPsec: IKEv2 negotiates SAs; ESP provides confidentiality and integrity; AH provides integrity only and is incompatible with NAT. Tunnel vs transport mode differ in header protection.

TLS 1.3 removes RSA key exchange and static DH, mandates forward secrecy (ECDHE), and reduces handshake to 1-RTT (0-RTT optional).

AAA: RADIUS (UDP 1812/1813) encrypts only the password; TACACS+ (TCP 49) encrypts the full payload and separates authentication, authorization, and accounting.

Zero Trust: never trust, always verify; microsegmentation, least privilege, and continuous verification replace perimeter-only models.

MACsec (802.1AE) secures Ethernet hop-by-hop with GCM-AES; it protects link-level traffic but not end-to-end paths.

NETCONF (SSH, port 830) uses YANG models and candidate/confirmed commit; RESTCONF maps YANG to HTTP methods; gNMI uses gRPC for streaming telemetry.

Ansible is agentless over SSH with idempotent playbooks; Terraform is declarative with state files and plan/apply; both support network device modules.

DDoS mitigation: RTBH (remotely triggered blackhole), BGP FlowSpec for surgical filtering, and scrubbing centers for volumetric attacks.

GPON downstream uses 1490 nm for data and 1550 nm for RF video overlay; upstream uses 1310 nm. XGS-PON shares the same outside plant and adds 1270 nm upstream with 10G/10G symmetric rates.

GPON split ratios: 1:32 typical, 1:64 max; budget class B+ is 28 dB, class C+ is 32 dB. Power budget = Tx power − receiver sensitivity − connector/splice losses − splitter loss.

Splitter loss ≈ 10·log10(N) + excess loss; a 1:32 splitter is about 15 dB plus 0.5–1 dB excess, so 1:64 adds roughly 3 dB.

ONT ranging in GPON uses equalization delay so all ONTs appear at equal logical distance; upstream bursts are separated by guard bands to avoid collisions.

VDSL2 vectoring cancels far-end crosstalk across bonded lines in the same binder; G.fast extends copper to 106 MHz/212 MHz with typical loop lengths under 250 m.

FTTH architectures: point-to-point (home run), active Ethernet (curb switch), and PON (passive split). PON minimizes fiber count and active elements in the field.

DSL line rate depends on loop length, gauge, and noise margin; raising target SNR margin by 3 dB typically reduces attainable rate by roughly 10–15%.

Ethernet OAM (Y.1731) provides continuity check, loopback, and delay/loss measurement; CFM maintenance domains are bounded by MEPs at domain edges.

5G NR numerologies: subcarrier spacing 15·2^μ kHz; slot length = 1 ms / 2^μ. FR1 is 410 MHz–7.125 GHz, FR2 is 24.25–71 GHz.

RAN split: CU handles RRC/SDAP/PDCP; DU handles RLC/MAC/high-PHY; RU handles low-PHY and RF. F1 is the CU–DU interface, E1 is CU-CP to CU-UP.

NSA (EN-DC) anchors LTE control plane and adds NR user plane; SA uses 5GC with NR as the sole RAT and enables network slicing and URLLC.

5G core SBA: AMF (access/mobility), SMF (session), UPF (user plane), AUSF/UDM (auth and subscription), PCF (policy), NRF (service registry), NSSF (slice selection).

Handover types: Xn-based (direct gNB–gNB), N2-based (via AMF), and inter-RAT. Measurement events A1–A6 govern NR intra/inter-frequency triggers.

Massive MIMO beamforming: 64T64R typical for mid-band; beam management uses SSB beams for initial access and CSI-RS beams for traffic.

QoS in 5G uses 5QI values mapped to QoS flows; GBR flows reserve resources, non-GBR are best effort; reflective QoS mirrors DSCP-like markings.

Network slicing combines S-NSSAI, dedicated UPF placement, and RAN resource partitioning; slice isolation is logical, not physically separate hardware.

OTN hierarchy: ODU0 (1.25G), ODU1 (2.5G), ODU2 (10G), ODU2e (10G LAN), ODU3 (40G), ODU4 (100G); OTU adds FEC and framing overhead.

OTN FEC: GFEC (RS(255,239), ~6.2 dB coding gain), EFEC (~8–9 dB), and oFEC for 400G; FEC choice trades gain against line rate overhead.

SDH/SONET: STM-1 = 155.52 Mbit/s, STM-4 = 622.08, STM-16 = 2.488 Gbit/s, STM-64 = 9.953 Gbit/s; VC-4 payload is 149.76 Mbit/s.

Protection: 1+1 (permanent bridge, hitless), 1:1 (standby, may carry extra traffic), MSP ring with 50 ms switch target; G.8032 ERPS provides sub-50 ms Ethernet ring protection.

FlexE decouples Ethernet MAC rate from PHY rate via bonding and sub-rating; it underpins 400G transport and supports hard client isolation.

Timing: SyncE distributes frequency over Ethernet PHY; IEEE 1588 PTP provides phase/time; class B/C/D clocks define holdover and accuracy grades.

WDM: CWDM uses 20 nm spacing over 1270–1610 nm (18 channels); DWDM uses 50 or 100 GHz grid on C-band (1530–1565 nm), with 80–96 channels at 50 GHz.

ROADM: CD (colorless/directionless), CDC adds contentionless, and C+L band expansion doubles capacity. OSNR budget = launch power − noise floor − span losses.

IPv4 header is 20 bytes minimum; TTL decrements per hop; fragmentation uses identification, flags, and fragment offset. IPv6 header is fixed 40 bytes with extension headers.

Subnetting: usable hosts = 2^(32−prefix) − 2 for /1–/30; /31 is point-to-point (RFC 3021), /32 is a host route.

OSPF uses link-state LSAs and Dijkstra SPF; areas reduce flooding, area 0 is backbone, and virtual links extend area 0 through non-backbone areas.

BGP best-path order: highest weight, highest local preference, locally originated, shortest AS path, lowest origin, lowest MED, eBGP over iBGP, lowest router ID.

MPLS: label stack operations push/swap/pop; LDP distributes labels for IGP routes; RSVP-TE or SR-TE provides traffic engineering. Segment Routing uses SID lists without per-flow state.

MPLS L3VPN uses VRF, RD (route distinguisher), and RT (route target) to isolate and import/export routes across PE routers.

Optical impairments: CD (chromatic dispersion), PMD, OSNR, and nonlinear effects (SPM, XPM, FWM). Coherent DSP compensates CD/PMD electronically.

400G ZR/ZR+ uses oFEC and QPSK/16QAM to reach 80–120 km in pluggable optics; 800G uses 8×100G or 4×200G lanes over shorter spans.

IPsec: IKEv2 negotiates SAs; ESP provides confidentiality and integrity; AH provides integrity only and is incompatible with NAT. Tunnel vs transport mode differ in header protection.

TLS 1.3 removes RSA key exchange and static DH, mandates forward secrecy (ECDHE), and reduces handshake to 1-RTT (0-RTT optional).

AAA: RADIUS (UDP 1812/1813) encrypts only the password; TACACS+ (TCP 49) encrypts the full payload and separates authentication, authorization, and accounting.

Zero Trust: never trust, always verify; microsegmentation, least privilege, and continuous verification replace perimeter-only models.

MACsec (802.1AE) secures Ethernet hop-by-hop with GCM-AES; it protects link-level traffic but not end-to-end paths.

NETCONF (SSH, port 830) uses YANG models and candidate/confirmed commit; RESTCONF maps YANG to HTTP methods; gNMI uses gRPC for streaming telemetry.

Ansible is agentless over SSH with idempotent playbooks; Terraform is declarative with state files and plan/apply; both support network device modules.

DDoS mitigation: RTBH (remotely triggered blackhole), BGP FlowSpec for surgical filtering, and scrubbing centers for volumetric attacks.