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

2. UCSC 2 Aman ShaikhWIRED Panel on Intra-domain Routing 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

3. UCSC 3 Aman ShaikhWIRED Panel on Intra-domain Routing 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?

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

5. UCSC 5 Aman ShaikhWIRED Panel on Intra-domain Routing 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

6. UCSC 6 Aman ShaikhWIRED Panel on Intra-domain Routing 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

7. UCSC 7 Aman ShaikhWIRED Panel on Intra-domain Routing 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

8. UCSC 8 Aman ShaikhWIRED Panel on Intra-domain Routing 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?

9. UCSC 9 Aman ShaikhWIRED Panel on Intra-domain Routing 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?