Switching

In my lab ,the edge switch is juniper  Ex2200 and core switch is H3C 5500

I have two uplink from edge to core.

I have enabled STP in the core switch, but I disabled STP in the edge.

Because the STP state of two downlink interface in the core switch are forwarding.

Dose BPDUs drop on the  interface when disabled STP protocol in the Ex2200？

If I use cicco 2950 to replace ex2200, and configured no spanning-tree vlan 1

In the core switch,  the STP state of two downlink interface one  is discard and the other is forwarding.

Sorry for my English

Hi,

I might be wrong, but believe that disabling spanning-tree on the interface means only that the EX itself will ignore the BPDUs. It should still forward such frames, though.

Can be wrong here, so would be happy if anyone could confirm or correct me here.

Cheers,

I hope so ！But  if Ex2200 can forward BPDUs, It should block one port of downlinks in the core switch when I show spanning status.

Unfortunately I can not  see that in my lab.

I have four kind of switches in my lab.(Huawei、H3C、Cisco、Juniper)

I don't think Ex will forward BPDUs if I disabe spanning-tree at global level.

I am new in jnous, I don't know if any configuration I should adjust in the Ex2200.

AAttachment file is my EX2200 config

Attachment(s)

config.txt   3 KB 1 version

Hello again, not sure if you saw my last post.

Please try changing this command:

protocols {
    igmp-snooping {
        vlan all;
    }

to this:

protocols {
    igmp-snooping {
        vlan all {
              disable
        }
}

-andrew

Thanks！

I have tried to disable igmp-snooping in vlan all then spanning-tree worked fine in core switch.

But I think that doesn't make sense.

Why does interface drop BPDUs packets when igmp-snooping enable？

Thanks for your assistance！

It is actually a bug that i first discovered because our EX was not passing LAT [1] traffic.  The problem number they assigned it was PR-448832.

Here are my notes from the investigation:

############

the problem is that in the ASIC juniper has treated all multicast traffic as IP multicast. When IGMP snooping is enabled the device does not forward the LAT packets becuase there are no igmp group members on any interfaces.  The problem is that this is in ASIC, and not in software so it is not really fixable...

We implemented a work around using a firewall filter to mactch the ethernet muliticast packets with an action of LOG. the idea is that forces the device to bring the packet up to the CPU which will then forward the packet that way overridding the ASIC´s built in drop behavior.

############

-andrew

[1] LAT (Local Area Transport) is an old, but really old Digital local area network protocol that works via multicast ethernet addresses.  

Hello,

I saw a similar problem of the EX not passing BPDUs with STP disabled when i had igmp-snooping enabled on our EX.

As a work around i disabled igmp-snooping on VLAN 1 and set each interface with "native-vlan-id 1".  

For me, it was also necessary to configure my other switches to treat the uplink with the EX as a shared media, otherwise spanning tree was not happy when it received BPDU´s from various switches on what it thought was point to point connection.  My other switches are Enterasys Matrix devices and the exact command is "set spantree portpoint false".

good luck

Andrew