Cisco SPRI 300-510 flashcards

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

OSPF Type 2 External Metric

The default external metric type. The route's cost is the redistributed metric alone, and the internal cost to the ASBR is used only as a tiebreaker between equal external metrics.

OSPF Forwarding Address

A field in type 5 and type 7 LSAs. Nonzero means the router should forward traffic toward that address instead of the advertising ASBR, avoiding an extra hop through the ASBR.

NSSA P-bit

The propagate bit in a type 7 LSA. When set by the ASBR, the NSSA ABR is allowed to translate the type 7 LSA into a type 5 LSA for the rest of the OSPF domain.

IS-IS ATT Bit

The attached bit set by a level-1/level-2 router in its level-1 LSP. Level-1 routers use it to install a default route pointing toward the nearest level-2 exit point.

IS-IS Wide Metrics

A TLV format allowing metrics up to 2^24 instead of the 6-bit narrow maximum of 63. Required for traffic engineering and for differentiating links with similar costs.

Redistribution Route Tagging

A route-map sets a tag on routes redistributed into a protocol, and the reverse redistribution denies that tag. This prevents feedback loops between two routing domains.

BGP Weight Attribute

A Cisco-proprietary, locally significant attribute. The path with the highest weight is preferred, and weight is never advertised to any BGP neighbor.

BGP Local Preference

A well-known discretionary attribute propagated within an autonomous system via iBGP but not sent to eBGP peers. The highest local preference wins before AS_PATH length is considered.

BGP MED Comparison Rule

By default MED is compared only among paths received from the same neighboring AS. The bgp always-compare-med command changes this to compare MED across all neighbors.

iBGP Split Horizon

A route learned from an iBGP peer is not advertised to another iBGP peer. Full mesh, route reflectors, or confederations are needed to propagate routes within the AS.

Route Reflector Client Rule

Routes from a client are reflected to clients and non-clients. Routes from a non-client are reflected only to clients, preventing loops among non-client peers.

BGP Confederation AS_PATH

Sub-AS numbers inside the confederation are hidden from external peers. The confederation ID is presented externally, and internal AS_PATH hops are not counted externally.

BGP Neighbor Active State

A neighbor stuck in Active means TCP port 179 cannot be established. Common causes are ACLs, missing routes, or unicast reverse-path forwarding blocking the connection.

BGP Next-Hop-Self

An iBGP configuration that rewrites the next hop of advertised routes to the local router's address, so internal peers do not need an IGP route to the external next hop.

LDP Label Distribution

LDP binds a label to each IGP prefix FEC and distributes the binding to peers over TCP port 646. Labels are locally significant and swapped at each hop.

RSVP-TE Path Signaling

RSVP-TE uses IP protocol 46 to signal label-switched paths. CSPF prunes links that fail bandwidth, affinity, or explicit-path constraints before the shortest path is computed.

MPLS TE Setup Priority

Each LSP has a setup and hold priority from 0 to 7. A lower number is more important, and preemption occurs when a new LSP cannot be placed otherwise.

Segment Routing Global Block

The SRGB is the label range reserved for global prefix SIDs. The global label equals the SID index plus the SRGB start value and should be consistent across the domain.

SR-MPLS Adjacency SID

A locally significant SID that identifies a specific link to a neighbor. It is used for explicit forwarding and for building segment lists in traffic-engineered paths.

SRv6 Segment Routing Header

An IPv6 extension header carrying the segment list. Each 128-bit SID encodes a locator and function, and SRv6-capable nodes process the list hop by hop.

PIM-SM Shared Tree

A (*,G) tree rooted at the rendezvous point. Sources register with the RP, and receivers join through IGMP toward the last-hop router before switching to the source tree.

PIM-SSM Requirement

Source-specific multicast requires IGMPv3 and a known source address. No RP is used, and the receiver builds an (S,G) tree directly toward the source.

Multicast RPF Check

A multicast packet must arrive on the interface that the unicast route to the source selects. A failed check drops the packet and increments RPF failure counters.

MSDP Source-Active Message

MSDP peers exchange source-active messages over TCP port 639 between RPs in different PIM-SM domains. It is not used for source-specific multicast.

Anycast RP

Multiple RPs share one loopback address. Sources and receivers converge on the nearest RP, and MSDP mesh groups or PIM anycast-RP keep the RPs synchronized.

mLDP Point-to-Multipoint LSP

Multicast LDP builds point-to-multipoint or multipoint-to-multipoint LSPs using LDP label mappings. It is commonly used as the transport for MVPN traffic in the core.

Non-Stop Routing

NSR synchronizes control-plane state between active and standby route processors, so a switchover does not require neighbors to re-establish adjacencies or sessions.

Non-Stop Forwarding

NSF uses graceful restart signaling and neighbor helper mode. Neighbors keep forwarding while the restarting router rebuilds its adjacencies and routing state.

BFD Detection Time

The detection time equals the negotiated transmit interval multiplied by the detection multiplier. A session down event triggers faster teardown than IGP hello timers.

BFD Echo Mode

Echo mode uses UDP port 3785 and reflects packets back from the neighbor to measure round-trip liveness. It is disabled by default and not supported on all platforms.

BGP PIC Backup Path

Prefix-independent convergence pre-installs a backup next hop in the forwarding table. When the primary path fails, traffic switches without waiting for BGP reconvergence.

TI-LFA Protection

Topology-independent loop-free alternate computes a post-convergence backup path using segment lists. It provides sub-50-millisecond protection and is preferred in segment routing deployments.