Hi everybody,
today I did some troubleshooting on customer site.
Following setup:
- L2 Multicast, one source and multiple end-devices on the same vlan
- inbound ACL on the core-VLAN-interface that only permits certain traffic (DNS, DHCP, ...)
We now realized that, when a multicast-stream is active, DHCP packets are not handled correctly. Debug on the Core-Router (which handles DHCP-relay) shows that there are very few requests, and they come with a huge delay. So we run into timeouts and clients will not get an IP address.
What intrigues me the most is, that other VLANs (that have nothing to do with the one where multicast is active, nor are affected by the ACL) also are affected.
Fixing is possible in 2 ways (at least, those 2 we found)
- disable the streamer port (or set it to a different vlan)
- remove/change the ACL (to specifically allow UDP:1234, the port that is used for our VLC-stream receivers)
None of these (at least from what I learned about Routing/Switching so far) should have an impact on DHCP/relay.
HW: C9500X, SW: 16.10.1, Virtual Stackwise
Any ideas and help are welcome :)
best regards,
Jochen
