CCNP-Studies
Routing
1-EIGRP
16 Eigrp Stub

RFC 7868: Section 6.7.6 – 0x0006 PEER_INFORMATION_TYPE

In EIGRP (Enhanced Interior Gateway Routing Protocol), configuring routers as stubs is a powerful feature that offers control over network behavior and helps optimize network performance. This documentation explains the concept of EIGRP stub routers, the types of stub routers, their benefits, and the associated TLV combinations.

EIGRP Stub Routers

Key Benefits of Stub Routers

  • The primary value of configuring a router as a stub in EIGRP is to limit the size and scope of the query domain within the network.
  • Stub routers inform their neighbors not to send query messages, essentially saying, "I am not a transit router for your traffic; do not send queries through me."
  • This feature is particularly advantageous in hub-and-spoke network topologies, such as DMVPN setups.

Query Scope Limitation

Stub routers limit the query scope in the following ways:

  • A stub router WILL reply to a query if the query is for a route that the stub router is advertising.
  • A stub router WILL send and originate queries like a regular EIGRP router.
  • In other words, stub routers can and do receive queries and will respond appropriately.

Types of Stub Routers

EIGRP supports various types of stub routers, each with specific purposes:

  • Connected: Advertises any connected interfaces (requires the use of the 'network' command).
  • Summary: Advertises summarized networks.
  • Receive-Only: Does NOT advertise any networks.
  • Redistributed: Advertises routes that have been redistributed INTO EIGRP.
  • Static: Advertises static routes.
  • Leak Map: Allows specific prefixes to be "leaked" or advertised from the stub router.
  • By default, if no specific options are indicated, the stub router is considered both "connected" and "summary."

EIGRP Stub TLV Combinations (0x0006 PEER_INFORMATION_TYPE)

EIGRP Stub TLV (Type-Length-Value) combinations specify how EIGRP handles different types of stub routers and their TLVs. These combinations help configure and fine-tune the behavior of stub routers in the EIGRP network.

  • Connected TLV (0x0001): Used for connected stub routers.
  • Summary TLV (0x0002): Used for summary stub routers.
  • Receive-Only TLV (0x0003): Used for receive-only stub routers.
  • Redistributed TLV (0x0004): Used for redistributed stub routers.
  • Static TLV (0x0005): Used for static stub routers.
  • Leak Map TLV (0x0006): Used for stub routers configured with leak maps.

Each TLV combination is associated with a unique hexadecimal value, as indicated in parentheses.

Verification

To verify and monitor the configuration of EIGRP stub routers and TLV combinations, use the following commands:

  • show ip eigrp neighbors detail: Displays detailed information about EIGRP neighbors, including stub router configurations.
  • show ip protocols: Provides information about routing protocols, including EIGRP configuration details.
  • debug eigrp packets hello detail: Enables debugging of EIGRP hello packets with detailed information.
  • debug eigrp packets terse detail: Enables debugging of EIGRP packets with terse and detailed information.
  • eigrp stub: Enters EIGRP stub router configuration mode.
  • show eigrp plugins: Displays information about EIGRP plugins and their configurations.

This documentation serves as a comprehensive guide to understanding and configuring EIGRP stub routers and their associated TLV combinations for efficient network management.

15 Ipv6 Summarization Leakmaps17 Eigrp Stub Leak Map