Configuration for MEP Requests

MEP Requests enable event building farm PCs to send requests for a specific number of events, thus enabling a simplified "pull" mechanism. MEP Requests are the only legitimate traffic that traverse upwards from the DAQ switch towards the Odin (Readout Supervisor) boards. To enable MEP Requests, the following configuration steps must be performed.

  • The Odin boards have 2 data network ports, only one of which is used for receiving MEP Requests. The convention is to use the MAC address ending with 00 for receiving MEP Requests, the one for receiving data has the MAC address ending with 01.

  • The IP Addresses on which the Odin boards may receive MEP Requests must be in the subnet

  • The Odin boards cannot respond to ARP requests. So the switch that they are connected to must have pinned MAC addresses. For example, one of the switches in D3, to which there exist Odin boards connected, is sw-d3b07-d1. Ensure that MAC addresses are pinned per VLAN, and not just on a port basis. This means when you type show mac-addresses vlan 10 on the switch console, you should see the following.
  MAC Address   Located on Port
  ------------- ---------------
  00ccbb-050501 12             
  00ccbb-050701 7              

  • The switch in d3 to which the Odins are connected are in turn connected to sw-daq-01. For the Odin boards to be reachable from the farm PCs, there must be a way for the MEP Requests to reach the switches in d3 from sw-daq-01. Hence, it is required to pin the ARP entries for the Odin boards on sw-daq-01.

  • On the HLT rack switches, there must be a route going to the Odin boards. In principle, any of the supposed 12 links from sw-daq-01 to the rack switches may be used to go up to the Odin boards. By convention we use only the first link, which is the one on port 35. The first VLAN has only two links to farm nodes to share the one link from sw-daq-01, so using this link for going upwards to the Odin boards will not cause a bottleneck anywhere. This route should show up as:     DAQVLAN11       11   static               1          1    

-- SaiSuman - 15 Aug 2007

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Topic revision: r1 - 2007-08-15 - SaiSuman
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