CCNA Spcor Architecture Questions

XGS-PON provides symmetric 10 Gbps, while GPON is asymmetric (2.5G/1.25G). Both use passive optical splitters and WDM.

E-Line is the MEF service for point-to-point Ethernet connectivity.

VPLS (Virtual Private LAN Service) emulates a multipoint Ethernet LAN over MPLS. VPWS is point-to-point, EVPN is modern but not always broadcast, and L3VPN is layer 3.

MP-BGP (Multiprotocol BGP) carries VPNv4 routes between PE routers, including the VPN label, enabling customer isolation and reachability across the MPLS core.

EVPN uses Ethernet Segment Identifier (ESI) for multi-homing. All-active mode allows load balancing across multiple PE nodes, and BGP control plane provides fast convergence via route withdrawal.

Ethernet Segment Identifier (ESI) and designated forwarder (DF) election in EVPN ensure that only one PE forwards traffic to the CE for a given Ethernet segment, preventing loops.

IOS XR uses a two-phase commit: the user commits, and if successful, the configuration is applied; otherwise, it rolls back. There is no need for explicit rollback commands.

GPON (Gigabit-PON) is defined by ITU-T G.984 with downstream up to 2.488 Gbps.

Distributed architecture with per-card allocation improves scalability and fault isolation. It does not directly reduce cost or simplify management; instead, it enhances performance and resilience.

uRLLC (Ultra-Reliable Low-Latency Communications) is designed for latency-critical and reliable applications.

GPON is a point-to-multipoint fiber access technology using passive optical splitters, providing downstream speeds up to 2.5 Gbps and upstream up to 1.25 Gbps.

Cisco NSO (Network Services Orchestrator) uses YANG models and NETCONF to manage service lifecycle.

Cisco CRS (Carrier Routing System) is a high-end core router designed for large service provider backbone networks, supporting MPLS, SR, and massive scale.

NSO uses NETCONF as the primary protocol for device configuration, leveraging YANG models.

An SDR provides a logical partitioning of router resources, allowing multiple independent virtual routers within a single physical chassis.

The ESI identifies a multi-homed device or network, enabling all-active redundancy and fast convergence.

Network slicing using dedicated resources via Flex-Algo or resource reservation can guarantee performance. Flex-Algo allows IGP to compute paths based on constraints like latency, providing dedicated paths for uRLLC.

VRF (Virtual Routing and Forwarding) instances provide separate routing tables per customer, ensuring isolation in L3VPN.

E-Tree (Ethernet Tree) is a rooted-multipoint service where the root can communicate with leaves, but leaves cannot communicate with each other.

The Cisco CRS is a carrier-grade router designed for the core/backbone with high MPLS scalability and IOS XR modularity. ASR 9000 is more for aggregation, NCS for edge/aggregation.

The commit/rollback model allows changes to be applied atomically and rolled back if errors occur, ensuring configuration consistency.

Q-in-Q allows multiple customer VLANs to be encapsulated within a service provider VLAN, increasing scalability.

Q-in-Q (802.1ad) allows service providers to stack a customer VLAN tag on top of a service VLAN tag, enabling scalable customer separation in metro Ethernet networks.

Network slicing divides a physical network into multiple virtual networks, each with dedicated resources. Slices can be tailored for specific services like eMBB, uRLLC, mMTC. They are not limited to 5G core but also include transport.

IOS XR uses distributed OS with process separation, and a commit/rollback model for configuration. It does not have a monolithic kernel; each protocol is a separate process. The admin plane is separate from SDRs.

IOS XR uses a commit/rollback configuration model. Changes are staged in a candidate configuration and committed; if issues arise, rollback to a previous commit is possible.

Cisco CRS (Carrier Routing System) is designed for the core with high capacity and MPLS capabilities.

The Cisco ASR 9000 series is optimized for the aggregation layer with dense 10GE/100GE ports and runs IOS XR.

GPON and XGS-PON are fiber-based PON technologies.

VPWS (Virtual Private Wire Service) or pseudowire provides a point-to-point Ethernet connection over MPLS.

VRF (Virtual Routing and Forwarding) provides separate routing tables per VPN on a PE router. MP-BGP carries VPN routes with labels, but isolation is achieved by VRF.

EVPN offers BGP control plane, multi-homing with ESI, and integrated L2/L3 services.

E-Line (Ethernet Line) is a point-to-point service defined by MEF for Carrier Ethernet.

ESI is used to identify a multi-homed site or Ethernet segment for all-active or single-active redundancy and to prevent loops.

NSO provides service lifecycle management by modeling services with YANG and configuring devices via NETCONF.

Cisco NCS (Network Convergence System) routers are designed for the aggregation layer, offering high port density and support for various services including mobile backhaul and business connectivity.

GPON (Gigabit Passive Optical Network) is a fibre-based access technology standardized by ITU-T.

Access layer provides connectivity to end users and aggregates traffic from various technologies.

P routers (core routers) perform label switching based on the MPLS label stack. They do not need to examine the IP header; they swap labels and forward accordingly.

VPLS relies on flooding for MAC learning (A) and often uses active/standby multi-homing (B), leading to inefficient bandwidth use.

IOS XR runs each protocol as a separate process, providing fault isolation and independent restart.

Cisco ASR 9000 is an aggregation router running IOS XR, suitable for L2/L3 services.

E-Line is a point-to-point Ethernet service defined by MEF. E-LAN is multipoint, E-Tree is rooted multipoint, E-Access is for access to a service provider network.

NSO (Network Services Orchestrator) uses YANG models and NETCONF for configuration management. Ansible, Cisco DNA Center, and Chef are other tools but NSO is specifically for service orchestration.

GPON uses Wavelength Division Multiplexing (WDM) with different wavelengths for downstream (1490nm) and upstream (1310nm) on the same fiber.

IOS XR runs each protocol as a separate process in protected memory, so a crash of one process does not affect others, improving stability.

VRF (Virtual Routing and Forwarding) creates separate routing tables for each customer, ensuring isolation.

The ESI (Ethernet Segment Identifier) and designated forwarder election ensure single active forwarding per segment. DF election is used for multi-homing.

EVPN uses ESI-based multi-homing with BGP control plane, offering faster convergence and active-active load balancing compared to VPLS's active/standby model.

EVPN uses BGP EVPN address family (AFI 25, SAFI 70) to exchange MAC/VPN routes for L2 and L3 services.

Process separation provides fault isolation; a crash in one protocol process does not affect others, improving overall system stability.

IOS XR uses a distributed OS with process separation; each protocol runs as a separate process in its own memory space, providing fault isolation.

IOS XR is a distributed OS (A), uses commit/rollback (B), and runs each protocol as a separate process (E). It does not have a monolithic kernel (C) and uses modular packages (D is true but not listed; actually IOS XR uses RPM packages, but 'single image' is false).

The admin plane is a special SDR used for managing the system (e.g., hardware inventory, shared resources). Default SDR is the primary forwarding SDR, but admin SDR is separate.

The ASR 9000 is a widely used aggregation router with IOS XR and supports L2/L3 services. CRS is core, NCS 5500 is edge/aggregation but more focused on 100GE, and ISR is enterprise.

Network slices are isolated virtual networks, but they share the same physical infrastructure; they do not have dedicated physical links.

Cisco CRS (Carrier Routing System) is a high-end core router supporting high-density 100GE and running IOS XR.

VRF (Virtual Routing and Forwarding) creates separate routing tables per customer, ensuring isolation.

The configuration management process handles commit/rollback and stores configuration in a database.

E-Line is the MEF service type for point-to-point Ethernet connections.

VRF (Virtual Routing and Forwarding) instances provide separate routing tables per customer, ensuring isolation in L3VPN.

The Cisco CRS (Carrier Routing System) is a core router platform with high-density interfaces and large scale for MPLS and Segment Routing.

The 'commit' command applies changes atomically; if any part fails, the entire commit is rejected.

Process separation prevents a failure in one protocol from affecting others, enhancing overall system stability.

IOS XR features a distributed OS and a commit/rollback configuration model.

GPON (Gigabit Passive Optical Network) uses passive splitters to share fiber among multiple subscribers.

VPWS (Virtual Private Wire Service) is a pseudowire that provides point-to-point L2VPN connectivity, emulating a physical wire.

IOS XR is a distributed OS with process separation and a commit/rollback model. Monolithic kernel and shared memory are not features.

The Cisco CRS (Carrier Routing System) is a high-end core router designed for the backbone of large SP networks.

SDR logically partitions a physical router into multiple independent routers, each with its own control plane and resources.

E-LAN (Ethernet LAN) service provides multipoint-to-multipoint connectivity, as per MEF standards.

The aggregation layer collects traffic from access nodes and forwards it to the core, often performing QoS, filtering, and subscriber management.

Secure Domain Router (SDR) provides logical separation of control plane resources, while admin plane is for system administration.

VPWS (Virtual Private Wire Service) is a point-to-point L2VPN service that emulates a wire, also called a pseudowire.

E-Line is a MEF standard for point-to-point Ethernet services, providing dedicated bandwidth and SLA guarantees.