Nokia SRA Composite flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

GPON wavelengths

Downstream data uses 1490 nm, upstream uses 1310 nm, and an optional 1550 nm overlay carries RF video. XGS-PON adds 1270 nm upstream for symmetric 10G operation.

GPON power budget

Budget equals transmit power minus receiver sensitivity minus connector, splice, and splitter losses. Class B+ allows 28 dB and class C+ allows 32 dB total.

Splitter loss formula

Loss in dB is approximately 10 times log base 10 of split count, plus excess loss of about 0.5 to 1 dB. A 1:32 splitter gives roughly 15 dB.

VDSL2 vectoring

Vectoring cancels far-end crosstalk among lines sharing a binder, letting bonded copper reach higher rates. G.fast extends this to 106 or 212 MHz over short loops.

5G NR numerology

Subcarrier spacing equals 15 times 2 to the power mu kHz, and slot length equals 1 ms divided by 2 to the power mu. FR1 is sub-7 GHz; FR2 is millimeter wave.

CU/DU/RU split

The CU hosts RRC, SDAP, and PDCP; the DU hosts RLC, MAC, and high PHY; the RU hosts low PHY and RF. F1 connects CU and DU.

5G core functions

AMF handles access and mobility, SMF handles sessions, UPF carries user plane, AUSF and UDM handle authentication and subscription, PCF handles policy, NRF is the registry.

NSA versus SA

NSA anchors control plane on LTE and adds NR user plane through EN-DC. SA uses the 5G core with NR only and enables slicing and URLLC.

OTN ODU rates

ODU0 is about 1.25 Gbit/s, ODU1 2.5, ODU2 10, ODU2e 10G LAN, ODU3 40, and ODU4 100. OTU adds framing and forward error correction.

OTN FEC gain

GFEC uses RS(255,239) and gives about 6.2 dB coding gain. EFEC gives roughly 8 to 9 dB, while oFEC supports 400G with higher overhead.

SDH STM rates

STM-1 is 155.52 Mbit/s, STM-4 is 622.08, STM-16 is 2.488 Gbit/s, and STM-64 is 9.953 Gbit/s. A VC-4 payload carries 149.76 Mbit/s.

G.8032 ERPS

Ethernet ring protection switching blocks one ring link and unblocks it on failure, targeting sub-50 ms recovery. It uses R-APS messages and per-ring VLANs.

FlexE purpose

Flexible Ethernet decouples MAC rate from PHY rate through bonding, sub-rating, and channelization. It enables 400G transport and hard client isolation.

SyncE versus PTP

SyncE distributes frequency over the Ethernet physical layer. IEEE 1588 PTP adds phase and time synchronization using timestamped message exchanges.

DWDM channel grid

DWDM uses 50 or 100 GHz spacing on the C-band from 1530 to 1565 nm, giving 80 to 96 channels at 50 GHz. CWDM uses 20 nm spacing.

IPv4 header size

The IPv4 header is at least 20 bytes and includes TTL, protocol, checksum, and fragmentation fields. The IPv6 base header is a fixed 40 bytes.

BGP best path order

Compare weight, then local preference, then locally originated, then shortest AS path, then lowest origin, then lowest MED, then eBGP over iBGP, then router ID.

MPLS label operations

Ingress pushes a label, transit routers swap labels, and egress pops the label. LDP distributes labels for IGP routes; RSVP-TE or SR-TE adds traffic engineering.

MPLS L3VPN components

A VRF creates per-customer routing tables, the RD makes prefixes unique, and route targets control import and export between provider edge routers.

Optical impairments

Chromatic dispersion, polarization mode dispersion, low OSNR, and nonlinear effects such as self-phase and cross-phase modulation limit reach. Coherent DSP compensates dispersion electronically.

400G ZR reach

400G ZR and ZR+ pluggables use oFEC with QPSK or 16QAM to reach roughly 80 to 120 km. 800G uses more lanes over shorter spans.

IPsec ESP versus AH

ESP provides confidentiality plus integrity and works through NAT. AH provides integrity only and is incompatible with NAT because it protects the IP header.

TLS 1.3 changes

TLS 1.3 removes RSA key exchange and static Diffie-Hellman, mandates forward secrecy with ECDHE, and completes the handshake in one round trip.

RADIUS versus TACACS+

RADIUS uses UDP 1812 and 1813 and encrypts only the password. TACACS+ uses TCP 49, encrypts the full payload, and separates authentication, authorization, and accounting.

Zero Trust principle

Never trust, always verify. Access decisions use least privilege, microsegmentation, and continuous verification instead of assuming a trusted internal perimeter.

MACsec scope

IEEE 802.1AE secures Ethernet links hop by hop with GCM-AES encryption and integrity. It protects each link but does not provide end-to-end path security.

NETCONF and YANG

NETCONF runs over SSH on port 830 and uses YANG data models with candidate and confirmed commit. RESTCONF maps YANG to HTTP; gNMI uses gRPC.

BGP FlowSpec

FlowSpec distributes match-and-action rules for traffic flows, enabling surgical DDoS filtering at line rate. RTBH instead drops all traffic to a target prefix.

Ansible versus Terraform

Ansible is agentless over SSH and runs idempotent playbooks procedurally. Terraform is declarative with a state file and plan/apply workflow for infrastructure.

1+1 versus 1:1 protection

In 1+1 the signal is bridged permanently to both paths and the receiver selects, giving hitless recovery. In 1:1 the standby path may carry extra traffic.

Segment Routing

Segment Routing encodes paths as ordered segment identifiers in the packet header, removing per-flow state from core routers. It supports SR-MPLS and SRv6 variants.

5QI and QoS flows

Each 5QI value defines latency, priority, and loss targets. GBR flows reserve resources, non-GBR flows are best effort, and reflective QoS mirrors markings.

NFV and SDN distinction

NFV virtualizes network functions onto commodity hardware. SDN separates the control plane from the data plane and centralizes forwarding decisions in a controller.