Panel on Intra-domain Routing WIRED 2003 Workshop on Internet Routing Evolution and Design

1. Panel on Intra-domain RoutingWIRED 2003Workshop on Internet Routing Evolution and Design Aman Shaikh University of California, Santa Cruz (UCSC) AT&T Labs - Research WIRED Panel on Intra-domain Routing

2. Where are we? • OSPF, IS-IS, RIP, EIGRP (Cisco only) • OSPF and IS-IS are reasonably well-understood • After all, just Dijkstra … (do I see a few smiles around?) • RIP: Who’s using it? • EIGRP • Large user-base: Cisco can tell us… • Vendors have worked pretty hard on their implementation • Good interoperability • Robust code WIRED Panel on Intra-domain Routing

3. What’s hot right now? • Super-fast convergence • Millisecond range? • Mostly focused on OSPF, IS-IS • Lower the timers • Super-efficient, super-scalable routing calculations (= Dijkstra) • But not at the cost of decreased stability • Use dampening for flapping elements • Bad news is bad; good news might be good • Will we achieve the holy-grail of supporting all kinds of services on IP networks? WIRED Panel on Intra-domain Routing

4. What issues need to be addressed? • IGP usage in real-networks • Configuration • Trouble-shooting • Interface with inter-domain routing • New protocols and technologies WIRED Panel on Intra-domain Routing

5. IGP Usage in Real Networks • Real networks use IGPs in variety of ways • Have led to quite a few hacks in IGPs • Example: • Stub areas to limit number of routes in an OSPF area • Not-so-stubby-areas (NSSAs) to limit “all-but-some” routes into an OSPF area • Cisco has two more options: total stubby, NSSA total stub • Multiple protocols within a single domain • Redistribution of routes from one to another • Redistribution of BGP routes into IGPs • Can IGPs scale? • Need to look at enterprise networks WIRED Panel on Intra-domain Routing

6. Configuration • Quite a few knobs to play with • Hierarchical routing • Example (OSPF/IS-IS): • Is “At most ‘n’ routers/area” a good rule? • Do we even need areas or we can do away with them by more efficient and scalable implementations? • Timers • session management • routing calculation • route-update propagation • Weight assignment • Traffic engineering, load-balancing • Impact on BGP WIRED Panel on Intra-domain Routing

7. Trouble-shooting • Need tools for monitoring protocols • OSPF and IS-IS are amenable to monitoring • OSPF/IS-IS monitoring products from PacketDesign and IPSUM • Research prototypes at AT&T and Sprint • How to tackle EIGRP and RIP? • Real-time analysis for early identification of problems • Often problems slowly deteriorate performance • Post-mortem analysis WIRED Panel on Intra-domain Routing

8. Interface with Inter-domain Routing • BGP uses IGPs for various things: • Forwarding: • To select closest exit-point (hot potato routing) • To determine the path to the exit-point • Control-plane: • I-BGP sessions are routed over IGPs • Is this the right interface? • Does this provide right amount of separation? • Example: why is BGP’s notion of “close-ness” equal to IGP path cost? WIRED Panel on Intra-domain Routing

9. New Protocols and Technologies • MPLS/LDP • Can call them layer 2.5, but that does not mean we do not have to address… • change in the forwarding paradigm and its impact • label-switching instead of longest-prefix match • tunneling through provider backbones • issues related to deployment, management, configuration, and operations • interaction with IGPs and BGP • Does the core become simpler or does it become even more complex? WIRED Panel on Intra-domain Routing