Buffering Walkthrough for IP Broadcast Traffic

Presenters : Nemanja Kamenica - Cisco

Year : 2019

dlp_document_download : AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 1 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 C U R A T E D B Y Buffering Walkthrough for IP Broadcast Traffic Nemanja Kamenica Technical Marketing Engineer Cisco I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 Agenda •Introduction - What is buffer? •Buffer Architecture – VOQ and Egress buffer •How buffer is used by unicast and multicast? •How buffering affects my broadcast traffic? •Implement QOS to protect broadcast traffic 2 AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 2 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 •Buffers on an ethernet switch ‒Traffic is sent from ingress to egress interface ‒It momentarily sits in buffer until it is scheduled to leave the egress interface •When do buffers come into play ‒Speed Conversion ‒Traffic Bursts ‒Many to one communication 3 Buffer 1 GE 1 GE 1 GE 1 GE 10 GE 10 GE I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 •Queueing is logical operation separation traffic in buffer •Scheduling is operation dequeuing traffic from a queue •Queues are scheduled based on algorithm •Some queues have scheduling priority over others ‒Strict priority queue ‒Regular queues 4 Queuing and Scheduling e1/1 Default -q q1 q2 q3 q4 q5 q6 q7 AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 3 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 5 Buffer types Ingress Egress N ports N ports VOQ Virtual Output Queue Input buffer for every egress port NxN buffer size Output Queue Buffer Shared buffer for N egress ports N buffer size Ingress Egress N ports N ports I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 •Majority (~90 -98%) of buffer is attached to ingress ports (~2 -10%), minor shared buffer is used by egress ports •Suitable for large external buffer architecture (Big buffer switches) •Ingress buffer is divided in Virtual Output Queues to simulate egress buffer and prevent Head of Line Blocking (HOLB) •Unicast traffic (most file based workflow) uses ingress large buffer •Multicast traffic (most LIVE workflow) uses egress shared buffers (smaller) 6 VOQ Buffer Ingress Egress N ports N ports VOQ Virtual Output Queue Input buffer for every egress port NxN buffer size AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 4 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 Ingress buffering for Broadcast traffic – Head of Line Blocking •SMTP 2022 -6, SMTP 2110, SMTP 2059 may be affected by HoLB that will affect multiple streams. 7 Ingress Module Egress Module Ingress Module Egress Module Ingress Module Egress Module Crossbar Fabric buffer I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 •Buffer is shared between egress ports, for both unicast and multicast traffic •Dynamic buffer allocation to ports under congestion •As every port has a N queues, no HoLB for unicast nor multicast •Suitable for on chip buffer architecture 8 Output Queue Buffer Output Queue Buffer Shared buffer for N egress ports N buffer size Ingress Egress N ports N ports AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 5 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 Buffers and Broadcast traffic - Jitter •SMTP 2022 -6, SMTP 2110, SMTP 2059 are multicast traffic streams ‒Requiring low latency and low jitter (jitter - change in latency) •Jitter can be results of traffic buffering, where packets are delayed because of congestion 9 Time Steady Stream of packets Same Stream of packets after congestion I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 How much buffer is needed? •Real time traffic should be forwarded immediately, without buffering for a long period that impacts latency and causes jitter •A switch must have sufficient buffers to absorb burst of an application •Dynamically shared buffer architecture, allows flexible use of buffer during burst and congestion, to provide optimal results ‒Queue -limit may be applied to ensure a single flow does not consume more than its fair share of buffers 10 AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 6 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 Quality of Service •Quality of Service can protect sensitive broadcast traffic •Live production traffic can take strict priority queue or high priority queue ‒Strict priority queue/high priority queue will protect sensitive traffic by dequeuing it first and keeping latency and jitter minimal •File based workflows can co -exist in the network, should take lower priority queue 11 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 Conclusion •Multicast Traffic does not use Ingress Buffers to avoid HoLB •ST2110 Traffic must be placed in high priority queue which is scheduled before any other traffic which avoids latency/jitter •Other traffic (file based) is placed in a lower priority queue •Proper QoS design ensures LIVE traffic is never impacted due to any congestion introduced by any other traffic 12 AIMS IP Showcase IBC 2019 September 2019 Curated by Video Services Forum vsf.tv 7 I P S H O W C A S E T H E AT R E AT I B C 2 0 1 9 : 1 3 –1 7 S E P T 2 0 1 9 Thank you Thank you to our Media Partners Presenter Name, Organization Email and phone number (recommended) 13