https://www.opradata.com/specs/48_Line_Notification_Common_IP_Multicast_Specification.pdf shows 48 multicast groups each for a subset of the option symbols. When there were 24 groups, the symbols starting with RU to SMZZZ were too heavy too voluminous for one multicast group, more so than the other 23 groups.
Our OPRA parser instance is simple and efficient (probably stateless) so presumably capable of handling multiple OPRA multicast groups per instance. We still use one parser per MC group for simplicity and ease of management.
From: Chen, Tao
Sent: Tuesday, May 30, 2017 8:24 AM
To: Tan, Victor
Subject: RE: OPRA feed volume
Opra data is provided by SIAC(securities industry automation corporation). The data is disseminated on 53 multicast channels. TP runs 53 instances of parser and 48 instances of rebus across 7 servers to handle it.