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BRKRST-2042.Pdf #CLUS Highly Available Wide Area Network Design David Prall, Principal Systems Engineer. CCIE #6508 BRKRST-2042 #CLUS Agenda • Introduction • Cisco IOS and IP Routing • Convergence Techniques • Design and Deployment • Final Wrap Up #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 3 Hidden Agenda • Introduction • Cisco IOS and IP Routing • Multiple Links/Multiple Paths • Load Sharing • Convergence Techniques • Interface Detection • Routing Protocols • Enhanced Object Tracking • First Hop Redundancy Protocols • Performance Routing • Cisco SD-WAN (Viptela) • Design and Deployment • MPLS Dual Carrier • MPLS + Internet #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 4 Your speaker • David Prall • Principal Systems Engineer • World Wide Enterprise Networking • [email protected] • CCIE 6508 (R&S/SP/Security) • Started at Cisco July 10, 2000 • Washington, DC #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 5 Cisco Webex Teams Questions? Use Cisco Webex Teams (formerly Cisco Spark) to chat with the speaker after the session How 1 Find this session in the Cisco Live Mobile App 2 Click “Join the Discussion” 3 Install Webex Teams or go directly to the team space 4 Enter messages/questions in the team space Webex Teams will be moderated cs.co/ciscolivebot#BRKRST-2042 by the speaker until June 18, 2018. #CLUS © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 6 Goals • Efficiently utilize available bandwidth • Dynamically respond to all types of disruptions • Leverage most effective design techniques that meet the design requirements • Review today’s technology #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 7 Where Can Outages Occur? Link or Device Failure MPLS - SP A C-A-R2 Link or Device Degraded C-A-R1 C-A-R4 C-A-R3 HQ-W1 BR-W1 MPLS - SP B HQ-W2 BR-W2 C-B-R1 C-B-R4 • How does outage manifest? • How quickly can network detect? • How long is bidirectional reconvergence? #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 8 Session Scope • What methods are used for path selection and packet forwarding • How does the network detect outages • Focus on network survivability and effective utilization rather than sub-second convergence • Modern Design using SD-WAN • Does not address “zero loss” considerations • Please review BRKRST-2365 Unified HA Network Design - The Evolution of the Next Generation Network • Other sessions delivered by Matt Birkner #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 9 Defining Availability Availability Downtime / Year • System Availability: a ratio of the 98.000000% 7.3 Days expected uptime to the 99.000000% 3.65 Days experienced downtime over a 99.500000% 1.825 Days period of time of the same duration 99.900000% 8.76 Hrs 99.990000% 52.56 Min Branch • Branch WAN High Availability: 99.999000% 5.256 Min WAN Between 99.99% and 99.999% 99.999900% 31.536 Sec HA Targets Ultra HA • Ultra High Availability: Between 99.999990% 3.1536 Sec Targets 99.9999% and 99.999999% 99.999999% .31536 Sec #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 10 Building Highly Available WANs Redundancy and Path Diversity Matter Downtime SINGLE per Year 99.95%* Downtime Downtime 99.90%* per Year per Year ROUTER, MPLS 4 Hours 8 Hours Internet SINGLE PATH 4–9 Hours 22 Minutes 46 Minutes ISR ISR Branch WAN HA Solution 99.995% 99.995% 99.995% SINGLE ROUTER, 26+ Minutes DUAL PATHS MPLS MPLS MPLS Internet Internet Internet ISR ISR ISR 99.999% 99.999% 99.999% DUAL ROUTERS, 5+ Minutes Internet DUAL PATHS MPLS MPLS MPLS Internet Internet ISR ISR ISR ISR ISR ISR * Typical MPLS and Business Grade Broadband Availability SLAs and Downtime per Year, calculated with Cisco AS DAAP tool. #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 11 Deployment Options MPLS/MPLS MPLS/Internet MPLS/LTE Internet/Internet Internet/LTE MPLS MPLS Internet Internet LTE/LTE LTE LTE 100’s of Combinations #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 12 Agenda • Introduction • Cisco IOS and IP Routing • Multiple Links/Multiple Paths • Load Sharing • Convergence Techniques • Design and Deployment • Final Wrap Up #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 13 Routing Table Basics Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override, p - overrides from PfR p 10.0.0.0/8 is variably subnetted, 14 subnets, 5 masks B p 10.0.0.0/8 [20/0] via 172.16.0.6, 00:12:36 B p 10.3.0.0/16 [20/0] via 172.16.0.6, 00:12:36 B p 10.4.0.0/16 [200/0], 00:13:52, Null0 C p 10.4.0.41/32 is directly connected, Loopback0 D p 10.4.1.0/24 [90/307200] via 10.4.49.2, 00:14:32, Ethernet0/0 C p 10.4.49.0/30 is directly connected, Ethernet0/0 L p 10.4.49.1/32 is directly connected, Ethernet0/0 B p 10.9.0.0/16 [20/0] via 172.16.0.6, 00:12:36 100.0.0.0/8 is variably subnetted, 9 subnets, 2 masks B 100.64.0.0/24 [20/0] via 100.64.3.1, 00:13:43 C 100.64.3.0/24 is directly connected, Ethernet0/2 L 100.64.3.2/32 is directly connected, Ethernet0/2 172.16.0.0/16 is variably subnetted, 9 subnets, 2 masks B 172.16.0.0/31 [20/0] via 172.16.0.6, 00:12:36 C 172.16.0.6/31 is directly connected, Ethernet0/1 L 172.16.0.7/32 is directly connected, Ethernet0/1 #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 14 INFORMATIONAL Administrative Distance Default • The distance command is used to configure Route Source Distance a rating of the trustworthiness of a routing Connected 0 information source, such as an individual Interface router or a group of routers Static Route 1 EIGRP Summary 5 • Numerically, an administrative distance is a Route BGP External positive integer from 1 to 255. In general, 20 the higher the value, the lower the trust (eBGP) rating EIGRP Internal 90 OSPF 110 • An administrative distance of 255 means the IS-IS 115 routing information source cannot be trusted RIP 120 at all and should be ignored EIGRP External 170 BGP Internal 200 (iBGP) Unknown 255 #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 15 Route Selection • How is administrative OSPF EIGRP OSPF distance used to determine which route should be installed? 10.0.14.0/24 10.0.14.0/24 10.0.14.0/25 These Two Routes • Only identical routes Are Identical are compared EIGRP Internal = 90 • Identical prefixes with OSPF = 110 different prefix lengths EIGRP Internal Installed are not the same route router#show ip route 10.0.14.0 255.255.255.0 Routing entry for 10.0.14.0/24 Known via "eigrp 1", distance 90, metric 307200, type internal • The route from the Redistributing via eigrp 1 protocol with the lower Last update from 10.0.121.2 on Ethernet0/1, 00:01:32 ago Routing Descriptor Blocks: administrative distance * 10.0.121.2, from 10.0.121.2, 00:01:32 ago, via Ethernet0/1 is installed Route metric is 307200, traffic share count is 1 Total delay is 2000 microseconds, minimum bandwidth is 10000 Kbit Reliability 255/255, minimum MTU 1500 bytes Loading 1/255, Hops 1 #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 16 Route Selection • What about longest prefix comparison? • Only identical routes are compared • Identical prefixes with different prefix lengths are not the same route • The route with the longest prefix is router#show ip route 10.0.14.0 255.255.255.0 longer-prefixes 10.0.0.0/8 is variably subnetted, 9 subnets, 3 masks installed D 10.0.14.0/24 [90/307200] via 10.0.121.2, 00:01:35, Ethernet0/1 O 10.0.14.0/25 [110/20] via 10.0.122.2, 00:00:50, Ethernet0/2 O 10.0.14.128/25 [110/20] via 10.0.122.2, 00:00:50, Ethernet0/2 #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 17 Agenda • Introduction • Cisco IOS and IP Routing • Multiple Links/Multiple Paths • Load Sharing • Convergence Techniques • Design and Deployment • Final Wrap Up #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 18 Load Sharing • Assume the same routing process attempts to install two routes for the same destination in the RIB • The routing process may allow the second route to be installed based on its own rules #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 19 CEF Load Sharing Per-Destination Per-Packet1 Default behaviour of IOS Universal Requires “ip load-sharing per- Algorithm “show cef state” packet” interface configuration1 Per-flow using destination hash Per-packet using round-robin method Packets for a given Packets for a given source/destination session will take source/destination session may take the same path different paths More effective as the number of Ensures traffic is more evenly destinations increase distributed over multiple paths Ensures that traffic for a given session Potential for packets to arrive out of arrives in order sequence #CLUS BRKRST-2042 © 2018 Cisco and/or its affiliates.
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