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Author Topic: Clafification on spanning Tree & MLT & LACP  (Read 1878 times)

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Offline AVAGO

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Clafification on spanning Tree & MLT & LACP
« on: February 15, 2019, 06:49:39 AM »
I have been looking through the forum and the guides and there seems some conflicting information.
its to do with the spanning tree and MLT, I have read that it should be off for an MLT and some say it should be ON.
or is it that spanning tree is on for all ports but the learning is off for the MLT, below is what I have run on the switch,
so I have two 5520 Stacked ( STK A ) with various VLANS then port 1/47,2/47 I have set as an MLT to another  switch stack ( STK B ) this uses 1/47 and 1/48 as the MLT
then from STK A I use ports 1/48,2/48 to connect to another  switch stack (STK C ) ports 1/47,1/48
the two  switch stacks are client stacks and have only one vlan ( or that's what it will be, My test setup is 2 switch Stack and then two stand alone switches. The info below if from the client switch

5520-48T-PWR(config)#mlt 1 name TRK-Stk-C-Stk-A
5520-48T-PWR(config)#mlt 1 me
5520-48T-PWR(config)#mlt 1 member 1/47,1/48
5520-48T-PWR(config)#mlt l
5520-48T-PWR(config)#mlt 1 learning disable
5520-48T-PWR(config)#mlt 1 enable
5520-48T-PWR(config)#spanning-tree mode rstp
5520-48T-PWR#save conf
5520-48T-PWR#copy conf nv
5520-48T-PWR#reload minutes-to-wait 1
5520-48T-PWR(config)#interface fastEthernet 1-46
5520-48T-PWR(config-if)#spanning-tree rstp port 1-46 edge-port true
5520-48T-PWR(config-if)#$ree bpdu-filtering port 6-44 enable timeout 60
5520-48T-PWR(config)#qos agent buffer large
5520-48T-PWR(config)#qos agent queue-set 2
5520-48T-PWR#save conf
5520-48T-PWR#copy conf nv
5520-48T-PWR#reload minutes-to-wait 1

520-48T-PWR(config)#sh running-config verbose module stp
! Embedded ASCII Configuration Generator Script
! Model = Ethernet Routing Switch 5520-48T-PWR
! Software version = v6.3.6.016
!
! Displaying all switch parameters
!====================================================
enable
configure terminal
!
! *** RSTP (Phase 1) ***
!
!The Spanning tree operation mode cannot be changed without rebooting.
!The Spanning tree operation mode is required to be set to RSTP before
!loading this ASCII configuration file.
spanning-tree mode rstp
spanning-tree rstp priority 8000
spanning-tree rstp version rstp
spanning-tree rstp forward-time 15 hello-time 2 max-age 20
spanning-tree rstp tx-holdcount 3
spanning-tree rstp pathcost-type bits32
no spanning-tree bpdu-filtering ignore-self
!
! *** RSTP (Phase 2) ***
!
spanning-tree rstp port ALL learning enable
spanning-tree rstp port 1-46 edge-port true
spanning-tree rstp port ALL priority 80
spanning-tree rstp port 47-48 edge-port false
spanning-tree rstp port ALL p2p auto
spanning-tree bpdu-filtering port 1-46 enable timeout 60
spanning-tree bpdu-filtering port 47-48 timeout 120
no spanning-tree bpdu-filtering port 47-48 enable
exit
5520-48T-PWR(config)#sh running-config verbose module mlt
! Embedded ASCII Configuration Generator Script
! Model = Ethernet Routing Switch 5520-48T-PWR
! Software version = v6.3.6.016
!
! Displaying all switch parameters
!====================================================
enable
configure terminal
!
! *** MLT (Phase 1) ***
!
no mlt
mlt 1 name "TRK-Stk-C-Stk-A" enable member 47-48
mlt 1 learning enable
mlt 1 bpdu all-ports
mlt 1 loadbalance basic

Some posts has said that STP should be disabled on the MLT but not on the port and others that say disable it on the MLT and the port.

And then to add even more confusion some say don't use MLT use LACP. All the switches I have are all AVAYA so should I stick with the MLT or is it better to use LACP ? or the LACP only really for when connecting to another Vendor i.e cisco/IBM etc
thanks for looking  :-\


Offline Paul L

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Re: Clafification on spanning Tree & MLT & LACP
« Reply #1 on: February 22, 2019, 03:35:33 PM »
always disable STP on MLT ports in connecting an ERS to another ERS or VSP.
Always.  "MLT 1 learning Disable"

you do this for several reasons.

1- you don't need it.  Don't want STP kicking in by accident.
2- In an ERS8000 ist Core SMLT links are automatically STP disabled. ON your ERS have to manually disable it.
3- On ERS you are given the option because if just doing MLT to MLT the other device might not be an ERS.


I am curious to know what documents are saying you shouldn't. 

ACSS- Avaya Enterprise Routing Switch  #8

Offline AVAGO

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Re: Clafification on spanning Tree & MLT & LACP
« Reply #2 on: February 25, 2019, 12:01:53 PM »
Hi Paul L
    thankyou for your reply, below is the link to the STP enable /Disable on MLT. Of course I probably have miss-understood the discussion

https://www.tek-tips.com/viewthread.cfm?qid=1485595

But from what you replied with, I should disable the STP/RSTP on the ports of the MLT's and also disable the learning on the MLT, all ports not part of an MLT should have STP/RSTP enabled and set with fast learning
below is what I have run on the switches, I'm using 5520/10
so below is from a client stack (c) to the server stack (A)

5520-48T-PWR(config)#mlt 1 name TRK-Stk-C-Stk-A
5520-48T-PWR(config)#mlt 1 me
5520-48T-PWR(config)#mlt 1 member 1/47,1/48
5520-48T-PWR(config)#mlt l
5520-48T-PWR(config)#mlt 1 learning disable
5520-48T-PWR(config)#mlt 1 enable
5520-48T-PWR(config)#spanning-tree mode rstp
5520-48T-PWR(config)#interface fastEthernet 1-46
5520-48T-PWR(config-if)#spanning-tree rstp port 1-46 edge-port true
5520-48T-PWR(config-if)#spanning-tree bpdu-filtering port 1-46 enable timeout 60
5520-48T-PWR(config)#qos agent buffer large
5520-48T-PWR(config)#qos agent queue-set 2

What I'm trying to achieve is the following

Stack A 2 x 5520
Ports 1/47,2/47   -----------> Stack B  Ports 1/47,3/47  (MLT-1 ) 1x5520 (Base) 2x5510
Ports 1/48,2/48  ------------> Stack C  Ports 1/48.3/47  (MLT-2 ) 1x5520 (Base) 2x5510
Stack A has various VLANs on it, Stack B & C just have 1 VLAN as its just PC's
Stack A will or should be the Root for the other two stack

Any further advice / corrections to my post appreciated
 

 

Offline Paul L

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Re: Clafification on spanning Tree & MLT & LACP
« Reply #3 on: February 25, 2019, 01:22:33 PM »
disable STP on all MLT ports.

I would trust Nortel/Avaya/Extreme docs.  Not tek-tips
ACSS- Avaya Enterprise Routing Switch  #8

Offline AVAGO

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Re: Clafification on spanning Tree & MLT & LACP
« Reply #4 on: March 05, 2019, 04:53:00 AM »
Hi thanks for the reply

Could someone shed some light on the issue I'm having with an MLT ,
For the purpose of my getting to know the Avaya 55xx switches we have, I have setup a test rig, this has a Stack of 3 switches ( Stack A ) and the 1 switch 1 MLT ( Stack B ) and 1 Switch 1 MLT ( Stack C )
on Stack A I have created two MLT's ( 1 & 2 )
in MLT 1 it has the following ports 1/47,3/47 this is linked to Stack B MLT 1 ports 47-48
MLT learning is disabled and the switches are using RSTP
Stack A can reach Stack B and from my laptop I can ping the addresses of Stack A & B ). To test the MLT I then removed the connection from port 47 stack B. I'm still able to ping both switches. Port 47 on Stack B was reconnected and port 48 was removed, again I was still able to ping bot switches.

Now here is the bit that I'm stuck on.
From Stack A on the MLT 2 ( 1/48,2/48 ) to Stack C ports 47-48. I have created the MLT on Stack C
but with both ports connected I can not reach stack C from Stack A or Stack B or my laptop
if I pull one of the connections from Stack C the switch is reachable but not with both
I have checked the MLT settings and leaning is disabled as is the spanning tree on the ports and both ends

I have reset back to factory defaults and then tried again but it fail's and I'm not sure why.

I have set Stack A to be the root ) spanning-tree priority 0000

Any advice gratefully received



 

Offline novice

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Re: Clafification on spanning Tree & MLT & LACP
« Reply #5 on: April 17, 2019, 11:07:21 AM »
disable STP on all MLT ports.

I would trust Nortel/Avaya/Extreme docs.  Not tek-tips

I have seen situations when tagged ports connecting to other switch not participating in STP/RSTP because of STP disabled on those ports. What that means is, every switch will then see itself as root bridge which is not what is wanted in a LAN segment.
One can check that by using command
show spanning-tree rstp status
and if the output shows the mac address of the switch on which the command was issued then it means that the switch see itself as root bridge. And there should only be one switch in the whole network thinking that.
As a best practice one should be configuring the root bridge with lower bridge priority using command
spanning-tree rstp priority 1000
When I enabled STP/RSTP, the correct root bridge's MAC address was shown as the root bridge.
Hence the conclusion is STP/RSTP should be enabled on the underlying ports of MLT. Whereas learning should be disabled for MLT itself.
« Last Edit: May 03, 2019, 03:21:38 PM by novice »