ripv2 overview€¦ · » path selection and loop prevention via bellman-ford algorithm • best...
TRANSCRIPT
RIPv2 Overview
Copyright © www.ine.com
In This Section
» RIPv2 Overview » Basic RIPv2 Configuration » Basic RIPv2 Verification
Copyright © www.ine.com
What is RIP?
» Routing Information Protocol • Distance Vector IGP • Standards Based
» Three versions • RFC 1058 - Routing Information Protocol • RFC 2453 – RIP Version 2 • RFC 2080 – RIPng for IPv6
Copyright © www.ine.com
Distance Vector vs. Link State Routing
» Distance Vector • RIP & EIGRP • Routers only know what directly connected neighbors tell
them • I.e. “Routing by Rumor”
• Only routes installed in the RIB are advertised » Link State
• OSPF & IS-IS • Routers know all the topology details within the flooding
domain • i.e. the area or level
Copyright © www.ine.com
Example DV vs. LS Advertisements
Copyright © www.ine.com
How RIPv2 Works
» Routes installed in the RIB are periodically advertised • Convergence is controlled by very basic timers • No active adjacencies, hence no fault detection
» Uses UDP port 520 for transport • Unreliable multicast updates to 224.0.0.9 by default • Can use both broadcast and unicast updates
Copyright © www.ine.com
How RIPv2 Works (cont.)
» Path selection and loop prevention via Bellman-Ford algorithm • Best path has the lowest hop count • Loop prevention via split-horizon, poison reverse, and
holddown timers • Slow to converge and suffers from count-to-infinity
problem
Copyright © www.ine.com
Configuring RIPv2
» Enable the global process • router rip
» Enable the interface process • network [address] • Matches major network only
» Verification • show ip protocols • show ip rip database • debug ip rip
Copyright © www.ine.com
RIP Versions
» Default processing • Send version 1 updates • Listen for versions 1 & 2 updates
» Modifying the version • version process level • ip rip receive version interface level • ip rip send version interface level
» Verification • show ip protocols
Copyright © www.ine.com
RIPv2 Summarization
» RIPv2 is classless • Performs automatic classful summarization by default • Disabled with no auto-summary under process
» With auto-summary on… • VLSM is supported within the same major network • Advertisements between major network boundaries are
summarized to classful boundary • Can result in traffic blackholes
Copyright © www.ine.com
RIPv2 Split-Horizon
» Updates received in an interface will not be sent back out the same interface • Undesirable on partial mesh NBMA networks • E.g. DMVPN
» Enabled by default on all interfaces except main interface in Frame Relay • no ip split-horizon to disable
» Verification • show ip interface
Copyright © www.ine.com
RIPv2 Update Types » Broadcast
• RIPv1 default • RIPv2 optional with ip rip v2-broadcast
» Multicast • RIPv2 default to 224.0.0.9
» Unicast • RIPv1 / RIPv2 optional • neighbor [address]
• Enables unicast update • passive-interface [interface]
• Suppress normal broadcast / multicast updates
Copyright © www.ine.com
RIPv2 Metric Calculation
» RIP uses hop-count as metric • 1 hop per interface • 16 is infinite
» offset-list to modify metric • access-list 0 means all routes
Copyright © www.ine.com
RIPv2 Convergence Timers
» Global • timers basic [update] [invalid] [holddown] [flush]
» Interface level • ip rip advertise [interval]
Copyright © www.ine.com All rights reserved.
Q&A