The New Policy for Enterprise Networking Robert Bays Chief Scientist June 2002

2 What Enterprises Need Apply business objectives to network policy –Lower operational costs with quick ROI –Optimize network performance Free existing technical resources from operational tasks

3 Proficient Networks Defines Enterprise Business Policy Current protocols were not designed to define complex business policies, nor should they Policy additions allow the enterprise finer control over their network than BGP –Time of day, link cost, path metrics complement existing BGP policy –Standard tasks - Explicit Engineering, Metrics Engineering, and Load Sharing

4 Business Policy Choices When and how often am I engineering? Where am I engineering to? What type of engineering am I doing?

5 Explicit Engineering Overview Enterprise need: –“I want all my VPN traffic to traverse my VPN provider during business hours.” Destination prefix and nexthop are known ASN ASN R1 R /8 explicit

6 Metrics Engineering Overview Enterprise need: –“I want to minimize jitter to my branch offices to increase the quality of my VoIP traffic.” Net B Net A R1 R /8 Test #2 Test #1

7 Metrics Engineering How It Works Hop limited probes determine last intermediate system in path Subsequent tests sends hop limited packets to last intermediate system in each path –latency, loss, jitter, packet trains, cost Path ranking based on test results Variance and hold-time to minimize route churn

8 Metrics Engineering Impact on the Enterprise Enterprise problem: –Path characteristics are constantly changing Impact of Metrics Engineering: –The Proficient Network Policy Engine consistently chooses the best path based on current path results

9 Load Sharing Overview Enterprise need: –“I want to distribute my traffic based on utilization and cost.” ASN R1 R2 ASN NetFlow ASN

10 Load Sharing How It Works Define cost schedules for each peer Gather flow information from Netflow or ethernet tap Distribute prefixes based on aggregate traffic rates minimizing costs After a prefix has been placed once, leave the prefix on that nexthop to minimize route churn AS-path variance

11 Load Sharing Impact on the Enterprise Enterprise problem: –Unpredictable costs and capacity Impact of Load Sharing: –Minimizes actual cost of transmitting a given amount of traffic, but total bill could increase –Traffic distribution may increase throughput by creating available bandwidth on a previously constricted link

12 Routing Update Process Overview IBGP peering sessions Inactive route discovery Only inactive routes originated from local peers tested Inactive routes monitored on user configurable intervals Entire prefix or a subnet inserted Inserted routes chosen based on local preference Routing updates only where necessary

13 Routing Update Sanity Overview NLRI is required before route insertion AS path modification No export community default

The Business of Networking Q&A

15 BGP Decision Process What is the deciding factor? Reason for path choice varies wildly depending on network architecture and peer choices –Border router, no policy: AS path length 5%, External BGP, 50%, IGP or router ID 45% –Core router, no policy: IGP or router ID –Policy usually accounts for 20% of path decisions where used Policy is not being used in most enterprise networks –Lack of expertise –Inability to achieve goals

16 BGP issues What needs to be changed for the Enterprise? The enterprise is primarily interested in recognizing long term path trends or network problems when they exist BGP usually doesn’t make bad decisions What determines of a “bad path” will vary depending on the enterprise needs Biggest problem is lack of customer understanding Standardized customer facing policies at the ISP level would help the enterprise more Give the enterprise tools to easily audit and understand what they can’t directly control