Cisco SPRI: Service Provider Advanced Routing Solutions: key terms

Flashcards for this exam Cisco SPRI: Service Provider Advanced Routing Solutions guide Class dates

• 6PECarrying IPv6 traffic over an IPv4 MPLS core using MP-BGP with labeled IPv6 routes, without VRFs.Advanced
• 6VPEIPv6 VPN service over an IPv4 MPLS core, using VPNv6 MP-BGP and VRF-aware IPv6 forwarding (RFC 4659).Advanced
• Address FamilyA BGP (or other protocol) configuration context identifying a type of network layer information, such as IPv4 unicast or L2VPN EVPN.Advanced
• Adj-RIB-InThe conceptual BGP table holding unprocessed routes received from a specific peer before inbound policy.Advanced
• Adjacency SIDA local segment that forces a packet across a specific IGP adjacency (link), regardless of shortest path.Advanced
• Allowas-InA BGP option permitting a router to accept routes containing its own ASN in the AS_PATH.Advanced
• Anycast RPConfiguring the same RP address on multiple routers for redundancy and load sharing, synchronized by MSDP or PIM.Advanced
• AS Path PrependingAdding extra copies of an ASN to the AS_PATH of advertised routes to make a path less attractive to other ASes.Intermediate
• AS-OverrideA PE-side BGP option that replaces the customer's ASN in the AS_PATH with the provider's ASN, letting sites with the same ASN learn each other's routes.Advanced
• AS_PATH AttributeA well-known mandatory BGP attribute listing the ASNs a route has traversed; used for loop prevention and path length comparison.Intermediate
• Attached BitA flag set in an L1/L2 router's Level 1 LSP signalling it has Level 2 connectivity, prompting L1 routers to install a default route.Advanced
• Autonomous System Number (ASN)A number identifying a BGP autonomous system: 2-byte (1-65535) or 4-byte (up to 4,294,967,295).Intermediate
• BGP Add-PathA BGP capability that allows advertising multiple paths for the same prefix to a peer.Advanced
• BGP Aggregate AddressA BGP command that creates a summary route when at least one component exists in the BGP table.Intermediate
• BGP Best Path SelectionBGP's ordered decision process for choosing one best path per prefix.Intermediate
• BGP CommunityAn optional transitive 32-bit BGP attribute (often written AS:value) used to tag routes for policy decisions.Intermediate
• BGP Conditional AdvertisementAdvertising a prefix to a peer only when another prefix is present (exist-map) or absent (non-exist-map) in the BGP table.Advanced
• BGP ConfederationSplitting one AS into multiple internal sub-ASes that run eBGP-like sessions among themselves, reducing iBGP mesh size.Advanced
• BGP FlowspecA BGP address family (RFC 8955) that distributes traffic filtering rules matching on packet fields, with actions such as drop or rate-limit.Advanced
• BGP Full MeshThe requirement that every iBGP speaker peer with every other iBGP speaker unless route reflectors or confederations are used.Intermediate
• BGP Labeled Unicast (BGP-LU)BGP distribution of labels for IPv4 or IPv6 prefixes (RFC 8277), used in Inter-AS Option C, Seamless MPLS and CsC.Advanced
• BGP Link-State (BGP-LS)A BGP address family that exports IGP topology and TE information to controllers such as PCEs.Advanced
• BGP Message TypesBGP's message types: OPEN, UPDATE, KEEPALIVE, NOTIFICATION and ROUTE-REFRESH.Intermediate
• BGP MultihomingConnecting an AS to two or more upstream links or providers using BGP for redundancy and traffic control.Intermediate
• BGP MultipathAllowing BGP to install multiple equal paths for a prefix for load sharing.Advanced
• BGP Neighbor StatesThe BGP finite state machine: Idle, Connect, Active, OpenSent, OpenConfirm and Established.Intermediate
• BGP Path AttributesProperties attached to BGP routes, categorized as well-known mandatory, well-known discretionary, optional transitive and optional non-transitive.Intermediate
• BGP Peer GroupA Cisco IOS construct that applies the same outbound policy to many neighbors and generates updates once per group.Intermediate
• BGP Prefix Independent Convergence (BGP PIC)A Cisco feature that precomputes backup BGP paths in the FIB so failover time does not depend on the number of prefixes.Advanced
• BGP Regular ExpressionPattern matching used in AS-path access lists to filter or select routes by AS_PATH contents.Intermediate
• BGP Route Reflector (RR)An iBGP router allowed to re-advertise iBGP-learned routes to its clients, removing the full-mesh requirement.Intermediate
• Bidirectional Forwarding Detection (BFD)A lightweight hello protocol that detects forwarding path failures in milliseconds and notifies routing protocols.Intermediate
• Border Gateway Protocol (BGP)The path-vector EGP (BGP-4) that exchanges reachability between autonomous systems and is the routing protocol of the Internet.Foundational
• Cisco IOS XRCisco's service provider operating system for platforms such as ASR 9000, NCS and 8000 series, with a commit-based configuration model.Intermediate
• Cluster ListAn optional non-transitive BGP attribute listing the cluster IDs of route reflectors a route has passed through.Advanced
• Constrained Shortest Path First (CSPF)A modified SPF that prunes links not meeting constraints (bandwidth, affinity, SRLG) before computing a path.Advanced
• Extended CommunityA 64-bit BGP community with type and value fields, used for route targets, site of origin, EVPN and other functions.Advanced
• External BGP (eBGP)A BGP session between routers in different autonomous systems.Foundational
• Fast Reroute (FRR)Precomputed local protection that switches traffic onto a backup path within about 50 ms of a failure.Advanced
• Flexible Algorithm (Flex-Algo)An IGP extension that lets operators define additional SPF algorithms (128-255) with custom metrics and constraints, each with its own prefix SIDs.Advanced
• Forwarding Equivalence Class (FEC)A group of packets forwarded the same way through an MPLS network, mapped to the same label.Intermediate
• Generalized TTL Security Mechanism (GTSM)Protection that accepts BGP packets only if their TTL is at or near 255, blocking spoofed sessions from distant attackers.Advanced
• Graceful RestartA mechanism letting neighbors keep forwarding through a restarting router's control plane using preserved forwarding state.Advanced
• Incremental SPF (iSPF)An optimization where only the affected portion of the SPF tree is recalculated after a change.Advanced
• Inter-AS MPLS VPNOptions for extending MPLS L3VPNs across autonomous systems: Option A (back-to-back VRF), B (VPNv4 eBGP between ASBRs) and C (multihop VPNv4 between RRs).Advanced
• Intermediate System to Intermediate System (IS-IS)A link-state IGP originally for OSI CLNS that runs directly over Layer 2 and is widely used in service provider cores.Intermediate
• Internal BGP (iBGP)A BGP session between routers in the same autonomous system.Intermediate
• IS-IS Level 1Intra-area IS-IS routing; L1 routers know only their own area and use the closest L1/L2 router for other destinations.Intermediate
• IS-IS Level 1/2 RouterAn IS-IS router participating in both levels, holding separate L1 and L2 databases, similar to an OSPF ABR.Intermediate
• IS-IS Level 2Inter-area (backbone) IS-IS routing between L2 and L1/L2 routers, which may be in different areas.Intermediate
• IS-IS Route LeakingAdvertising selected Level 2 prefixes into Level 1 so L1 routers choose optimal exits instead of the nearest default.Advanced
• IS-IS Wide MetricsIS-IS extended 24-bit interface and 32-bit path metrics carried in TLVs 22 and 135, replacing the 6-bit narrow metric.Advanced
• Label Distribution Protocol (LDP)A protocol that distributes label bindings for IGP prefixes between MPLS neighbors.Intermediate
• Label Edge Router (LER)An MPLS router at the edge of the label-switched domain that imposes or removes labels, typically a PE router.Intermediate
• Label Forwarding Information Base (LFIB)The data-plane table mapping incoming labels to outgoing labels, operations and next hops.Advanced
• Label Information Base (LIB)The table of all label bindings a router has learned from LDP neighbors, plus its own local bindings.Advanced
• Label StackThe ordered set of MPLS labels on a packet; routers act only on the top label.Intermediate
• Label Switch Router (LSR)Any router that forwards MPLS packets based on labels; core LSRs are called P routers.Intermediate
• Label Switched Path (LSP)The unidirectional path a labeled packet follows from ingress to egress LER through an MPLS network.Intermediate
• LDP-IGP SynchronizationA feature that keeps the IGP from using a link until LDP is operational on it, preventing traffic blackholing.Advanced
• Link-State PDU (LSP)The IS-IS packet that carries a router's link-state information, analogous to an OSPF LSA.Intermediate
• Local Preference (LOCAL_PREF)A well-known discretionary BGP attribute shared among iBGP peers; the highest value is preferred for outbound traffic from the AS.Intermediate
• Loop-Free Alternate (LFA)A precomputed backup next hop that is guaranteed loop-free, enabling sub-50 ms IGP fast reroute.Advanced
• Maximum-PrefixA BGP neighbor limit on the number of prefixes accepted, protecting against route leaks and table overflows.Advanced
• MPLS LabelA 32-bit shim header containing a 20-bit label value, 3-bit Traffic Class (EXP), 1-bit bottom-of-stack flag and 8-bit TTL.Intermediate
• MPLS Layer 3 VPN (L3VPN)A provider service (RFC 4364) that carries customer IP routes in separate VRFs across an MPLS core using MP-BGP.Advanced
• MPLS Traffic Class (TC)The 3-bit field in an MPLS label (formerly EXP) used to carry QoS markings across the core.Advanced
• MPLS Traffic Engineering (MPLS TE)Steering traffic along explicit, constraint-based paths using RSVP-TE tunnels to use network capacity efficiently.Advanced
• Multi-Exit Discriminator (MED)An optional non-transitive BGP attribute that suggests to a neighboring AS which entry point to use; lower is preferred.Intermediate
• Multicast Source Discovery Protocol (MSDP)A TCP-based protocol (port 639) that shares active source information between RPs in different PIM domains or anycast RP sets.Advanced
• Multicast VPN (mVPN)Technology for carrying customer multicast across an MPLS L3VPN, using GRE/PIM (draft-Rosen) or BGP and mLDP/P2MP RSVP-TE.Advanced
• Multipoint LDP (mLDP)LDP extensions for building point-to-multipoint and multipoint-to-multipoint LSPs, used for multicast VPN.Advanced
• Multiprotocol BGP (MP-BGP)Extensions to BGP (RFC 4760) that carry routing information for multiple address families such as IPv6, VPNv4, EVPN and multicast.Advanced
• Multiprotocol Label Switching (MPLS)A forwarding technology that switches packets using short labels instead of IP lookups, enabling VPNs, traffic engineering and fast reroute.Intermediate
• Network Entity TitleThe IS-IS router address in NSAP format, containing the area ID, system ID and NSEL of 00.Intermediate
• Next-Hop-SelfA BGP neighbor option that rewrites the NEXT_HOP to the router's own address when advertising to iBGP peers.Intermediate
• NEXT_HOP AttributeA well-known mandatory BGP attribute giving the IP address to forward toward for a prefix.Intermediate
• Nonstop Routing (NSR)A high-availability feature where the standby route processor maintains full routing protocol state so neighbors never notice a switchover.Advanced
• On-Demand Next Hop (ODN)A Cisco SR-TE feature that automatically instantiates an SR policy when a BGP route arrives with a matching color community.Advanced
• Originator IDAn optional non-transitive BGP attribute set by a route reflector to the router ID of the route's original iBGP source.Advanced
• OSPF Down BitA flag a PE sets in Type 3/5/7 LSAs sent to a CE so other PEs will not redistribute them back into MP-BGP.Advanced
• OSPF Sham LinkA logical intra-area link between PEs across the MPLS backbone so VPN routes are preferred over an OSPF backdoor link.Advanced
• OSPF Stub Router AdvertisementOSPF max-metric router-lsa: advertising maximum link cost so other routers avoid transiting this router.Advanced
• Overload BitAn IS-IS LSP flag telling other routers not to use this router for transit traffic.Advanced
• Path Computation Element (PCE)A controller or router that computes paths for headends, communicating via PCEP.Advanced
• Path Computation Element Communication Protocol (PCEP)The TCP-based protocol (port 4189) between a PCE and path computation clients for path requests, updates and delegation.Advanced
• PE-CE RoutingThe routing protocol between a provider PE (in a VRF) and a customer CE: static, eBGP, OSPF, EIGRP, IS-IS or RIP.Advanced
• Penultimate Hop Popping (PHP)The MPLS behavior where the next-to-last router removes the top label so the egress router does only one lookup.Advanced
• Prefix SIDA global segment associated with an IGP prefix that steers traffic along the ECMP-aware shortest path to that prefix.Advanced
• Private AS NumberASN ranges 64512-65534 (2-byte) and 4200000000-4294967294 (4-byte) reserved for private use and not routed on the Internet.Intermediate
• Provider Edge Router (PE)A service provider router that connects to customer edge devices and holds customer VRFs in MPLS VPNs.Intermediate
• Provider RouterA service provider core router that only switches labeled packets and has no customer-facing interfaces or VPN routes.Intermediate
• Remote-Triggered Black Hole (RTBH)A DDoS mitigation technique where a BGP-signaled route sends attack traffic to a discard (Null0) next hop at the network edge.Advanced
• Resource Public Key Infrastructure (RPKI)A cryptographic system that lets networks validate that an AS is authorized to originate a prefix (route origin validation).Advanced
• Resource Reservation Protocol (RSVP)A signaling protocol (IP protocol 46) that reserves resources along a path, used by IntServ and MPLS TE.Advanced
• Route Distinguisher (RD)A 64-bit value prepended to an IPv4 prefix to make it a unique VPNv4 route, allowing overlapping customer addresses.Advanced
• Route Flap DampeningA BGP mechanism that suppresses routes that repeatedly flap by assigning penalties that decay over time.Advanced
• Route Policy Language (RPL)The IOS XR policy language using route-policy blocks with if/then/else logic and named sets instead of route maps.Advanced
• Route RefreshA BGP capability that lets a router ask a peer to resend its routes so new inbound policy can be applied without resetting the session.Intermediate
• Route Target (RT)A BGP extended community that controls which VRFs export and import VPN routes, enabling topologies like hub-and-spoke and extranet.Advanced
• RSVP-TERSVP extensions used to signal MPLS TE LSPs with explicit routes, bandwidth reservations and label distribution.Advanced
• Segment Identifier (SID)An identifier for a segment: an MPLS label in SR-MPLS or an IPv6 address in SRv6.Advanced
• Segment Routing (SR)A source-routing architecture where the ingress node encodes a path as an ordered list of segments, with no per-flow state in the core.Advanced
• Segment Routing Global Block (SRGB)The label range reserved on each router for global SR-MPLS prefix SIDs, default 16000-23999 on Cisco.Advanced
• Segment Routing Header (SRH)An IPv6 routing extension header (routing type 4) that lists SRv6 segments and a Segments Left pointer.Advanced
• Segment Routing Traffic Engineering (SR-TE)Traffic engineering using SR policies identified by headend, color and endpoint, steering traffic onto explicit or dynamic segment lists.Advanced
• Shared Risk Link Group (SRLG)A group of links that share a common physical resource, such as a conduit, and could fail together.Advanced
• Site of Origin (SoO)A BGP extended community identifying the customer site a route came from, preventing loops at multihomed sites.Advanced
• Soft ReconfigurationA BGP option that stores unmodified inbound routes from a neighbor so policy can be re-applied locally.Advanced
• SR-MPLSSegment routing using the MPLS data plane, where each segment is an MPLS label.Advanced
• SRv6Segment routing over the IPv6 data plane, where segments are IPv6 addresses carried in the destination address and optional Segment Routing Header.Advanced
• Targeted LDP (T-LDP)An LDP session between non-adjacent routers using unicast hellos, used for pseudowires and remote LFA.Advanced
• Topology-Independent Loop-Free Alternate (TI-LFA)A segment routing fast reroute method that provides 100 percent link, node and SRLG protection using the post-convergence path.Advanced
• Transit ASAn autonomous system that carries traffic between two other autonomous systems.Intermediate
• Unicast Reverse Path Forwarding (uRPF)A feature that drops packets whose source address is not reachable via the routing table, mitigating spoofing.Advanced
• VPNv4 Address FamilyThe MP-BGP address family that carries 12-byte VPN-IPv4 routes (RD + IPv4 prefix) and VPN labels between PEs.Advanced
• Well-Known BGP CommunitiesReserved communities with standard meaning: NO_EXPORT, NO_ADVERTISE, NO_EXPORT_SUBCONFED (local-AS) and others.Intermediate