Virtual Router to Support Multicast

##### ISSUE TYPE

* Improvement Request

##### COMPONENT NAME

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Virtual Router
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##### CLOUDSTACK VERSION

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4.19.1.1
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##### CONFIGURATION

##### OS / ENVIRONMENT

##### SUMMARY

Currently Cloudstack Virtual Router doesnt support Multicast from external networks (eg. Private Gateway).

In our case, our customers require multicast support because they decode Stock Market Feeds from the Stock Exchange. And Majority Stock Exchange distributes market feeds in ITCH format, which is Multicast.

In order to overcome this limitation now, we had to resort to VNF + L2 Networks.

I also have a curious question, if Cloudstack VR does not support multicast, then why is there a UDP Protocol option in the Network ACL Rules?

##### STEPS TO REPRODUCE

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##### EXPECTED RESULTS

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For VR to support multicast natively
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##### ACTUAL RESULTS

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VR does not support multicast at the moment.
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A issue identifica o Virtual Router do CloudStack e solicita suporte nativo a multicast para redes externas, mas não menciona arquivos, testes, comandos ou pontos de entrada. Comece localizando a implementação de rede do Virtual Router e os testes existentes de protocolo ou roteamento. O trabalho estará concluído quando o tráfego multicast funcionar nativamente por meio do Virtual Router para o caso de uso descrito de redes externas.

Escrita pelo modelo de indexação a partir do texto da issue.