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Name Resolution

Name Resolution is the process by which CCNP translates content names into routing information that enables data delivery. In CCNP's name-centric model, resolution maps human-readable content names to the network locations where content is available, functioning as the backbone of content-centric routing.

Resolution Process

When a client requests content by name, the network must determine where copies of that content exist. This is the fundamental role of Name Resolution: given a content name, return one or more content locations that can satisfy the request.

Unlike traditional DNS, which maps hostnames to IP addresses, CCNP Name Resolution maps content names to content locations—specific network endpoints where content is available. Since CCNP allows multiple copies of content to exist throughout the network, a single content name can resolve to multiple locations. The resolution system returns all known locations, allowing the requesting router to select among them based on metrics like latency, bandwidth, or cache freshness.

Resolution Architecture

CCNP Name Resolution operates through a hierarchical system of resolution caches and authoritative sources:

Content Store Resolution: The first check occurs in the router's own Content Store. If the requested content is cached locally, resolution succeeds immediately—no network querying required. This is the fastest path and represents the common case for popular content.

Pending Interest Table (PIT) Chaining: When multiple pending requests exist for the same content, routers can aggregate requests rather than generating duplicate resolution queries. This reduces load on resolution infrastructure and improves response times for burst requests.

Forwarding Information Base (FIB) Lookup: The FIB maps name prefixes to next-hop faces. For names without local cache, the router performs longest-prefix-match lookup to determine where to forward the interest. The FIB is populated by routing protocol updates and may point directly to content publishers or intermediate aggregators.

Hierarchical Resolution: For names not found in local caches or FIB, resolution queries traverse hierarchical resolution infrastructure. Namespace Providers maintain authoritative resolution data for their delegated namespaces, responding to queries about content within their domain.

Namespace Hierarchy in Resolution

The namespace structure directly influences resolution behavior. Names consist of components separated by slashes, with the leftmost components representing higher-level namespace segments. Resolution follows this hierarchy:

  • Top-level segments (com, edu, gov, net, org, app, data, media) are typically delegated to root Namespace Providers
  • Second-level and subsequent segments are delegated to organizations or individuals
  • Full content names resolve through the chain of delegation to authoritative sources

When resolving /com.example.app/doc/intro, the resolution system might query in sequence:

  1. Root namespace for com delegation
  2. Example's namespace server for app delegation
  3. Example's app namespace for doc/intro content location

Hierarchical resolution enables efficient caching at each level and provides clear authority for namespace segments.

Resolution and Caching

A critical feature of CCNP Name Resolution is that resolution results are cacheable. Unlike DNS, which historically had short TTLs to enable fast updates, CCNP's immutable content model means resolution results can be cached aggressively. A content name that resolves to a particular location today will resolve to the same location tomorrow—content at a given name never changes location without receiving a new name.

This caching enables several optimizations:

  • Resolution results cached at multiple network points dramatically reduce resolution traffic
  • Popular content names typically resolve from cache with no originator queries
  • Resolution infrastructure sees queries only for uncached or less-popular content

The Content Store at each router integrates with resolution, storing not just content but also resolution hints about where additional copies might be found.

Resolution Performance

Name Resolution performance directly impacts overall network latency. Resolution times of milliseconds matter in time-sensitive applications. Several techniques optimize resolution:

  • Aggressive caching: Resolution results cached close to requesters minimize repeat resolution
  • Pre-resolution: Popular content names pre-resolved during network idle periods
  • Anycast: Resolution servers deployed at multiple geographic locations
  • Negative caching: Failed resolution attempts cached to avoid repeating failures

Large-scale Namespace Providers operate global resolution infrastructure with thousands of servers, ensuring resolution queries complete within 50ms for most users.

Resolution Security

Name Resolution includes security mechanisms to prevent hijacking and ensure authenticity. DNSSEC-style signatures protect resolution data, and Namespace Providers cryptographically sign resolution responses. Clients verify signatures before accepting resolution results, preventing man-in-the-middle attacks on the resolution process.

See Also