My Core Exploded And All I Got Was This Lousy T-Shirt Vijay Gill

What Is The Problem The amount of state is increasing. Real problem So what? Real problem Nasty surprises that result from interactions between current routing implementations, increased state, CPU, and message processing.

Examples Run to completion processing may cause missed hellos Frame Relay meltdowns Time diameter exceeds hold down Pegged CPU on primary causes slave to initiate takeover Decoupled Hello processing from Routing Process

Types of State Amount of state is approximately the same Where it is and how the protocols deal with it are different Lean IGPs Reasons for Lean IGP Carry Prefixes in iBGP Primary state growth is in BGP Focus on BGP

Prefixes in a Promising Local ISPs Network

Resource Consumption # of Paths vs. # of Prefixes Large amounts of peering Crunch RIB to populate FIB More state requires more CPU time Delayed Convergence

RIB

FIB

Insufficient Resources Memory Fragmentation Solved Problem – Hope springs eternal Flap BGP Sessions Failure cascade Packet forwarding and downstream peering failures Learned Routes Forwarding Table

Route Establishment

Growth Trends RIB Growth is Linear FIB Growth is Sub-linear RIB has multiple views/paths FIB only has the Forwarding Table Regardless of the number of paths/routes, only few forwarding entrys are installed in the FIB

Scaled RIB/FIB Memory Usage Time Money

Results Headroom seems to consist of 100k more prefixes Supra-linear growth trend Two years: Consumption /14 every 4 months or so. Today, less than 2 months.

Peer Updates

This is a problem Transient routing loops Potential for wide scale disruption of routing functionality Missed Keepalives May never Converge Choke point is updating peers

RIP V2 Forever! Questions and Answers