Multicast Performance Measurement on the vBNS NANOG 20 (Washington, DC) October 24, 2000 Robert Beverly

Background End-to-End nightly performance tests run since early 1995 across vBNS Goal: Develop analogous tests for multicast No longer possible to rely on crontab entries for test synchronization (1:N vs 1:1) Developed out-of-band signaling protocol to control tests

Network Details Tests utilize Sun Ultra2 hosts with OC12c ATM interfaces in each network POP PVC to local Juniper M40 Juniper M40s have both POS (OC48c) and ATM (OC12c) links to other backbone network nodes POS links preferred PIM-SM domain

Signaling Protocol Signaling protocol designed to allow maximum flexibility Allows for arbitrary multicast topologies Uses TCP for reliability Messages: –Health check –Send N packets of size S on group G at rate R –Receive N packets on group G

Test Operation 1.Coordinator checks health of all daemons 2.Coordinator selects one sender and ten receivers 3.Coordinator sends receive control instructions 4.Receivers send IGMP membership reports 5.Coordinator sends transmit control instruction 6.Receivers collect loss and packet misordering

7.Receiver receives last expected packet or times out waiting on final packet 8.Coordinator waits for acknowledgements from all receivers 9.Coordinator gathers loss information, generates graphs and tables 10.Select different transmitter, repeat Test Operation

Test Details Addresses selected from GLOP (RFC 2770) Administratively scoped Why ATM? –Models actual vBNS customer access method –Already deployed across all vBNS POPs –Easily controlled traffic shaping

Control Host (Washington) Expect Multicast Packets from Group (G)

Control Host (Washington) IGMPv2 Membership Report for Group (G)

Control Host (Washington) Send to Group (G)

Control Host (Washington) RP Register Test Traffic to Group G

Control Host (Washington) (S,G) State Installed

Control Host (Washington) Traffic Test Traffic to Group G Traffic via Shared Tree

Control Host (Washington) (SPT Built using PIM-SM) (S,G) State Installed

Control Host (Washington) Receivers now see traffic via SPT

Control Host (Washington) Receiver Report (includes which packets were lost)

Test Results Nightly test results available at: Both absolute and time relative loss presented Nature of loss (bursty, continuous, etc) Result data validated with OCxMONs

Test Results – Loss Report Multicast Loss Percentage [Wed Oct 11 00:11:43 EDT 2000] Packets: Pkt Size: 4000 Bytes Rate: 10 Mbps Receiver SRC AST DNG DNJ HAY HSJ NOR PYM RTO SEJ WAE WOR ast dng dnj hay hsj nor pym rto sej wae wor

Test Results – SNMP Polling ROOT: jn1.ast.vbns.net (Null hostent.) ROOT: (jn1-so ast.vbns.net) 1: (jn1-so mej.vbns.net) [0:04:05] [56142] 2: jn1.dng.vbns.net (Null hostent.) [0:04:39] [56142] ROOT: (jn1-so ast.vbns.net) 1: (jn1-so mej.vbns.net) [0:04:07] [56142] 2: (jn1-so dng.vbns.net) [0:04:40] [56142] 3: jn1.dnj.vbns.net (Null hostent.) [0:04:08] [56096] ROOT: (jn1-so ast.vbns.net) 1: (jn1-so wae.vbns.net) [0:04:47] [53185] 2: (jn1-so wor.vbns.net) [0:04:12] [53149] 3: jn1.nor.vbns.net (Null hostent.) [0:04:12] [53107] ROOT: (jn1-so ast.vbns.net) 1: (jn1-at wae.vbns.net) [0:04:50] [53185] 2: jn1.pym.vbns.net (Null hostent.) [0:04:13] [50016]

Detected 484 lost pkts (50016 expected) 0.968% percent loss Test Results – Loss Pattern Detected 72 lost pkts (50016 expected) 0.144% percent loss ast dng

Test Results – Practical Application Detect performance problems –Loss –Reordering Determine vBNS backbone multicast performance Detect multicast routing anomalies Detected lost tunnel PIC

Causes of Loss State initiation delay Congested network path or network element Routing instabilities Inherently unreliable protocol (UDP)

Practical Implementation Problems No way to get OSPF routes into Juniper MRIB (inet.2) in JunOS 4.x Forced to export Sun /30 routes into iBGP via a JunOS policy statement IGMP membership reports must be carried in optioned IP packets for the Juniper to recognize them (contrary to RFC) Danger in running native multicast on production routers

Multi-Megabit Multicast Successfully demonstrated high-date rate multicast from 1 sender to 10 receivers 1Million 4k Byte packets at 380Mbps Between 0.443% and 0.830% loss Backbone M40 routers perform very well, shared memory architecture Currently trying to scale Sun performance hosts to even higher rates

Other Multicast Measurement Tools Netcom Systems SmartMulticastIP – pplications/0300_0025RevE_SmartMulticast.asphttp:// pplications/0300_0025RevE_SmartMulticast.asp NLANR Multicast Beacon – MRM –

Multicast Benchmarking Documents RFC2432: Terminology for IP Multicast Benchmarking Draft-ietf-bmwg-mcastm-04.txt: Methodology for IP Multicast Benchmarking

Further Research Full line rate (~580Mbps) testing Group capacity testing Mixed-Class Throughput Latency/Jitter Measurements

Questions?