1 / 8

Composite Link Framework Issues

The proposed solution aims to summarize routing advertisements for composite links, ensuring that the routing protocol can converge within necessary timeframes to meet network performance goals. This involves analyzing the trade-offs of aggregating routing information, such as scalability and path computation speed against potential signaling challenges like crankback and loop scenarios. By optimizing the way component links are advertised and utilizing advanced features like incremental flooding and jumbo frames, we can enhance IS-IS scalability and improve overall network efficiency.

tamber
Télécharger la présentation

Composite Link Framework Issues

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Composite Link Framework Issues

  2. Functional requirement #1 The solution SHALL provide a means to summarize routing advertisements regarding the characteristics of a composite link such that the routing protocol converges within the timeframe needed to meet the network performance objective.

  3. To Aggregate or Not? • Pro: • More scalable: less information in IGP • Quicker path computation (NBD) • Con: • Crankback during signaling

  4. Crankback • Loop • Compute path across network • Signal path • If success, exit • Exclude link that just failed • Iterate

  5. Costs of crankback • Still have to advertise composite link in IGP • Only saved components • Each failed signaling attempt takes time • There may not be a working path • Ergo: signaling may take an arbitrarily long time • Failure information from one setup may not apply to another: start over

  6. Benefits of crankback • Skip characterizing component • Max bandwidth (4B + 2B overhead) • Max reservable bandwidth (4B + 2B overhead) • Unreserved bandwidth (4B + 2B overhead) • Latency (4B float + 2B overhead) • Component Index (4B id + 2B overhead) • Delay variation (4B id + 2B overhead) • TLV overhead (2B) • Total: 36B per component

  7. IS-IS scalability • IS-IS LSP space: 256 possible fragments • Fragment: 1200B, partially filled, fixed header • Estimate: 80% fill • Some overhead for other TLVs: 75% fill • Available space: 230KB -> 7,000 components • Flooding time: 230KB @ 1Gb/s ~= 2ms • Incremental flooding makes this MUCH shorter • Typically 1 LSP

  8. More LSP space • Increase fragment size • Jumbo frames • More fragments: RFC 5311 • Add additional system IDs • Gives 256 fragments per ID

More Related