CommScope RUCKUS Community Forums

ys · ‎03-20-2024

Recently I faced network outage due to a lot of packet storm.
I did not identify it was due to broadcast or not. but I would like to know possibility.

I have L3 link and L2 trunk link from switch-A (ICX7750) to switch-B (ICX7450) with config below.
In case of happening broadcast from vlan 1 accidentally, any possibility to broadcast storm loop on vlan 1?
Also possibility to forward these broadcast packets to eth1/1/3 connecting to different switch?

Because route-only L3 interface is still a member of vlan1 by default on ruckus switches.

---
!
! SWITCH-A
!

vlan 1 name DEFAULT-VLAN by port
!
vlan 3000 name LAB by port
tagged ethe 1/1/2
router-interface ve 3000
spanning-tree 802-1w
spanning-tree 802-1w priority 0
loop-detection
!

int e 1/1/1
port-name To-SWITCH-B_L3
route-only
ip address xxx.xxx.xxx.xxx/31
!

int e 1/1/2
port-name To-SWITCH-B_L2
!

int e 1/1/3
port-name To-SWITCH-ZZZ_L3
route-only
ip address zzz.zzz.zzz.zzz/31
!

---
!
! SWITCH-B
!

vlan 1 name DEFAULT-VLAN by port
!
vlan 3000 name LAB by port
tagged ethe 1/1/2
untagged ethe 1/1/9 to 1/1/10
spanning-tree 802-1w
loop-detection
!

int e 1/1/1
port-name To-SWITCH-A_L3
route-only
ip address xxx.xxx.xxx.yyy/31
!

int e 1/1/2
port-name To-SWITCH-A_L2
!

int e 1/1/9
port-name User Port
!
int e 1/1/10
port-name User Port
!

jdryan · ‎03-22-2024

Hi ys,

Here, the ingress would come from switch A port :
int e 1/1/1
port-name To-SWITCH-B_L3
route-only
ip address xxx.xxx.xxx.xxx/31

As there is route-only specifed there on the port same should work as an L3 interface and not forward L2 frames.

As Switch B :
int e 1/1/1
port-name To-SWITCH-A_L3
ip address xxx.xxx.xxx.xxx/31

is being used as an L3 interface : would suggest that route-only command be impletmented there.

Its recommended for route-only to be in place for L3 interfaces [ ports configured as L3 interfaces],
As ingress L2 suppression feature, should be able to help supress broadcasts, in an event any are transmitted over that link.

As per the set up done, over the L3 link between SW A and SW B : L2 traffic should not be seen.

With respect to : no switchport : by cisco, I may not be able to comment on that.

Let me know if the details help.

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CommScope RUCKUS Community Forums

possiblity of broadcast storm loop between L3 interface and L2 interface