Adding a second switch kills multicast traffic

Hi all,

I'm encountering a mysterious issue with a pair of switches I'm working with. I openly profess my ignorance and hope someone will be kind enough to point me in the right direction so that I can learn about what's happening.

I have a Dell N3048 as a primary switch, and I just came into possession of an HP Aruba 3810M. I currently have a few Macs, a FreeNAS, and a bonjour printer connected to the N3048, all of which are visible to each other over mDNS/Bonjour. However, a few minutes after I connect an uplink to the 3810M I noticed that mDNS and Bonjour pretty much dies on the entire network. As soon as I disconnect the 3810M, almost instantly mDNS and Bonjour is happy again.

This is all within a single VLAN. I'm not trying to traverse VLANs or anything. The only thing plugged into the 3810M is a single known-good machine, and an uplink to the N3048 where everything else is plugged into.

The 3810M has multiple user manuals, one of which is dedicated to multicast routing alone, and it's over 400 pages. I'm finding it very difficult to narrow down what I'm dealing with here. Could someone give me a pointer? Thank you!

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Aruba 3810M config:

; JL076A Configuration Editor; Created on release #KB.16.08.0002 ; [REDACTED] hostname "Aru3810" module 1 type jl076x module 2 type jl076y module 3 type jl076z flexible-module A type JL083A mdns enable dhcp-snooping dhcp-snooping vlan 1-2 igmp filter-unknown-mcast igmp lookup-mode ip timesync ntp ntp server-name "0.pool.ntp.org" ntp server-name "1.pool.ntp.org" ntp server-name "2.pool.ntp.org" ntp server-name "3.pool.ntp.org" ntp enable ip default-gateway 10.1.1.1 ip dns server-address priority 1 1.1.1.1 interface 1 dhcp-snooping trust dhcpv6-snooping trust exit interface A1 dhcp-snooping trust dhcpv6-snooping trust exit snmp-server community "public" unrestricted oobm ip address dhcp-bootp exit vlan 1 name "DEFAULT_VLAN" untagged 1-48,A1-A4 ip address 10.1.1.249 255.255.255.0 ip igmp ip igmp version 3 jumbo exit vlan 2 name "VLAN2" tagged 1-48,A1-A4 ip address 10.2.1.249 255.255.255.0 ip igmp ip igmp version 3 jumbo exit spanning-tree spanning-tree 1 loop-guard spanning-tree A1 loop-guard no tftp server loop-protect disable-timer 300 no autorun no dhcp config-file-update no dhcp image-file-update password manager password operator 

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Dell N3048 Config:

!Current Configuration: !Software Capability "Stack Limit = 8, VLAN Limit = 1024" !Image File "N3000AdvLitev6.5.3.4" !System Description "Dell EMC Networking N3048, 6.5.3.4, Linux 3.6.5-e3cd5a07, Not Available" !System Software Version 6.5.3.4 ! configure vlan 2 name "vlan2" exit slot 1/0 3 ! Dell EMC Networking N3048 slot 1/1 6 ! Dell EMC N3000 SFP+ Card stack member 1 4 ! N3048 exit interface out-of-band ip address 10.1.1.241 255.255.0.0 10.1.1.1 exit system jumbo mtu 9216 interface vlan 1 ip address 10.1.1.241 255.255.255.0 exit username "admin" password [REDACTED] privilege 15 encrypted application install SupportAssist auto-restart start-on-boot application install hiveagent start-on-boot ip dhcp snooping ! interface Gi1/0/1 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/2 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/3 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/4 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/5 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/6 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/7 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/8 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/9 ip dhcp snooping trust switchport mode trunk exit ! interface Gi1/0/10 ip dhcp snooping trust switchport mode trunk exit ! interface Te1/0/1 ip dhcp snooping trust switchport mode trunk exit 

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