ViAggre: Making Routers Last Longer! Hitesh Ballani Paul Francis, - PowerPoint PPT Presentation

ViAggre: Making Routers Last Longer! Hitesh Ballani Paul Francis, Tuan Cao and Jia Wang Cornell University and AT&T Labs – Research HotNets 2008

Motivation: Rapid Routing Table Growth 300000 300000 282,000 prefixes 282,000 prefixes Active BGP entries (FIB Size) Active BGP entries (FIB Size) (Sep’08) (Sep’08) 250000 250000 200000 200000 150000 150000 100000 100000 50000 50000 0 0 88 88 90 90 92 92 94 94 96 96 98 98 00 00 02 02 04 04 06 06 08 08 Year Year

Motivation: Rapid Routing Table Growth 500000 500000 ?? Active BGP entries (FIB Size) Active BGP entries (FIB Size) Rapid future growth 400000 400000 300000 300000 ◮ IPv4 exhaustion 200000 200000 ◮ IPv6 deployment 100000 100000 0 0 88 88 90 90 92 92 94 94 96 96 98 98 00 00 02 02 04 04 06 06 08 08 14 14 Year Year

Typical Router Innards Route Processor CPU RIB Line Card Line Line Line Card Card Card FIB ASIC

Typical Router Innards Route Processor Routing Information Base CPU RIB (DRAM $) Line Card Line Line Line Card Card Card FIB ASIC

Typical Router Innards Route Processor CPU RIB Line Card Line Line Line Card Card Card FIB ASIC Forwarding Information Base (SRAM $$$)

Does (FIB) Size Matter? Technical concerns ◮ More Memory ◮ More Processing ◮ Power and Heat dissipation problems

Does (FIB) Size Matter? Technical concerns ◮ More Memory ◮ More Processing ◮ Power and Heat dissipation problems Business concerns ◮ Less cost-effective networks ◮ Price per byte forwarded increases ◮ Router memory upgrades

Does (FIB) Size Matter? Technical concerns ◮ More Memory ◮ More Processing ◮ Power and Heat dissipation problems Business concerns ◮ Less cost-effective networks ◮ Price per byte forwarded increases ◮ Router memory upgrades ISPs are willing to undergo some pain to reduce FIB size

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05]

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05] Separate edge from the core

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05] Geographical routing

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05] Compact routing

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05] All require architectural change So many ideas, so little impact!

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05] Tackle routing scalability through a series of incremental, individually cost-effective upgrades

Routing Scalability Problem Space [Deering, ’96] [O’Dell, ID’97] [Zhang et. al., ICNP’06] FIB growth [Farinacci, ID’07] RIB growth [Massey et. al., ID’07] [Jen et. al., HotNets’08] [Francis, CNIS’94] Routing Convergence, [Deering et. al., ID’00] Update Churn, .... [Hain, ID’02] [Krioukov et. al., Arxiv’05] This Paper: Focuses on reducing FIB size

Virtual Aggregation, aka ViAggre A “configuration-only” approach to shrinking router FIBs ◮ Applies to legacy routers ◮ Can be adopted independently by any ISP Key Insight: Divide the routing burden A router only needs to keep routes for a fraction of the address space

Talk Outline ◮ Introduction[]y ◮ ViAggre: Basic Idea[]y ◮ ViAggre Design[]y ◮ Evaluation[]y ◮ Deployment[]y ◮ Conclusions

ViAggre: Basic Idea 0.0.0.0 IPv4 Address Space PoP C PoP A 255.255.255.255 PoP B External External Router Router ISP Today: All routers have routes to all destinations

ViAggre: Basic Idea 0.0.0.0 Virtual 0/2 Prefixes 64/2 128/2 PoP C PoP A 192/2 255.255.255.255 PoP B External External Router Router ISP Divide address space into Virtual Prefixes (VPs)

ViAggre: Basic Idea 0.0.0.0 Virtual 0/2 Prefixes 64/2 128/2 192/2 255.255.255.255 Aggregation Points for Green VP External External Router Router Assign Virtual Prefixes to the routers Routers only have routes to a fraction of the address space

ViAggre: Basic Idea 0.0.0.0 Virtual 0/2 Prefixes 64/2 128/2 192/2 255.255.255.255 Aggregation Points for Green VP External External Router Router How to achieve such division of the routing table? Without changes to routers and routing protocols Without cooperation from external networks

Talk Outline ◮ Introduction[]y ◮ ViAggre: Basic Idea[]y ◮ ViAggre Design[]y ◮ Evaluation[]y ◮ Deployment[]y ◮ Conclusions

ViAggre Control-Plane 0.0.0.0 0/2 64/2 128/2 192/2 Full Routing Table 255.255.255.255 External External Router Router eBGP Peers may advertise full routing table

ViAggre Control-Plane 0.0.0.0 0/2 64/2 128/2 192/2 Full Routing Table 255.255.255.255 External External Router Router Load full routing table into RIB Supress all but blue routes from FIB FIB Suppression Blue routers only load blue routes into their FIB

Data-Plane paths 0.0.0.0 0/2 64/2 128/2 Packets destined to a prefix in Red 192/2 Virtual Prefix 255.255.255.255 External External Router Router Consider packets destined to a prefix in the red VP

Data-Plane paths 0.0.0.0 0/2 64/2 A 128/2 1 192/2 2 I A2 255.255.255.255 E External X External Router Router ViAggre path Ingress (I) → Aggregation Pt (A) → Egress (E)

Ingress → Aggregation Point 0.0.0.0 0/2 64/2 A 128/2 1 192/2 I A2 255.255.255.255 E External X External Router Router Router I doesn’t have a route for destination prefix

Ingress → Aggregation Point 0.0.0.0 0/2 Advertise 64/2 A Red VP 128/2 1 192/2 I A2 255.255.255.255 E External X External Router Router Aggregation Points advertise corresponding Virtual Prefixes

Ingress → Aggregation Point 0.0.0.0 0/2 Advertise 64/2 A Red VP 128/2 1 192/2 I A2 255.255.255.255 Prefix Next-Hop E External .... X P1 External Router .... P2 Router A 0/2 .... 128/2 .... 192/2 Blue router has a route for the red Virtual Prefix

Aggregation Point → Egress 0.0.0.0 Prefix Next-Hop P3 X 0/2 .... P4 .... 64/2 64/2 A .... 128/2 .... 128/2 192/2 192/2 2 I A2 255.255.255.255 E External X External Router Router Aggregation Pt. A tunnels packet to external router

Aggregation Point → Egress 0.0.0.0 0/2 64/2 A 128/2 1 192/2 I A2 255.255.255.255 E External X External Strip tunnel header Router Router from outgoing pkts Egress Router strips the tunnel header off outgoing packets

Failure of Aggregation Point 0.0.0.0 0/2 64/2 A 128/2 1 192/2 I A2 255.255.255.255 E External X External Router Router What if Aggregation Pt. A fails?

Failure of Aggregation Point 0.0.0.0 0/2 64/2 A 128/2 192/2 I A2 255.255.255.255 Prefix Next-Hop E External .... X P1 External Router .... P2 Router 0/2 A2 .... 128/2 .... 192/2 Router I installs the route advertised by A2

Failure of Aggregation Point 0.0.0.0 0/2 64/2 A 128/2 192/2 I A2 255.255.255.255 Prefix Next-Hop E External .... X P1 External Router .... P2 Router 0/2 A2 .... 128/2 .... 192/2 Packets are re-routed appropriately

ViAggre’s impact on ISP’s traffic 0.0.0.0 0/2 64/2 A 128/2 1 192/2 I A2 255.255.255.255 E External X External Router Router ViAggre paths can be longer than native paths Traffic stretch, increased router and link load, etc.

Popular Prefixes Traffic volume follows power-law distribution ◮ 95% of the traffic goes to 5% of prefixes ◮ Has held up for years Install “Popular Prefixes” in routers ◮ Stable over weeks ◮ Mitigates ViAggre’s impact on the ISP’s traffic