While building QoS mechanisms between MSR2000/3000 routers, I create a mirror port to monitor the router link port with Wireshark to verify proper DSCP marking, policing, etc.
Most traffic is displayed with the correct marking. Using an advanced ACL, we mark inbound and outbound system traffic (OSPF, SNMP) for high priority. The OSPF traffic leaving the monitored router does not show the correct marking, however. Fortunately, the ingress packets are correct when they arrive at the peer router (the important part!), but strangely those same egress packets do not appear wth the appropriate marking on a local mirrored port.
That makes me curious. Does mirroring occur before QoS is applied to some (system-level) packets? Do I need a special switch on the mirror group to enable viewing of the raw router protocols as they are actually transmitted? Or can that be seen only on the peer for some reason?
Are other protocols or types of traffic subject to the same issue?
I haven't found any documentation that provides the internal structure and connectivity for the MSR. Detailed info would be valuable to help design QoS. Is that info available anywhere?
Thanks,
Bud
#routing#ospf#QOS#remark#DSCP#mirror