Junos OS

Hi, I am having an issue with MSTP, I have two routers attached to each other using an aggregated link configured as a trunk and allowing all vlan to pass through

_____________           ____________

|                             |          |                            |

|        EX4200 1   | ====|       EX4200 2   |

|____________ |          |____________|

This is the core of the switching network, it employs VRRP where ex4200-1 is the master for the VRRP and ex4200-2 is the backup. Now we have other switches connected to the two core switches that don't run MSTP, but this is okay since we have rstp on them.

Now the problem is whenever I configure MSTP on the two core switches they loose their VRRP relationship and they are both showing as master for their respective VRRP. VRRP works fine when we only employ RSTP. VRRP is employed on Vlan interfaces and for all MSTI the aggregated link is in the forwarding mode. We need to employ MSTP to make use of the the links lower down on the network.

Please help

Hello,

It will help if you do the following:

1. Make EX4200_1 Root Bridge for CIST and desired MSTIs(if you configured any).

2. Make EX4200_2 as Secondary Root Bridge for CIST and Root for desired MSTIs.

3. Lower the STP cost of the Trunk link betwee this two switches(just in case)

You have to keep in mind the following:

1. You should have the same MSTP Region Name

2. You should have the same version

3. You should have the same Vlans mapped to MSTIs on all switches that's part of MSTP. 

Ouput from Ex4200 2

Interface    Port ID    Designated      Designated         Port    State  Role
                         port ID        bridge ID          Cost
ae0.0            128:1        128:1  16384.28c0da31ce00      5000  FWD    ROOT
ge-0/0/0.0     128:513      128:513  20480.5c5eab67e780    200000  FWD    DESG
ge-0/0/3.0     128:516      128:516  20480.5c5eab67e780    200000  FWD    DESG
ge-0/0/12.0    128:525      128:525  20480.5c5eab67e780    200000  FWD    DESG
ge-0/0/13.0    128:526      128:526  20480.5c5eab67e780    200000  FWD    DESG
ge-0/0/14.0    128:527      128:527  20480.5c5eab67e780    200000  FWD    DESG
ge-0/1/0.0     128:609      128:609  20480.5c5eab67e780     20000  FWD    DESG
ge-0/1/1.0     128:610      128:610  20480.5c5eab67e780     20000  FWD    DESG
ge-0/1/2.0     128:611      128:611  20480.5c5eab67e780     20000  FWD    DESG
ge-0/1/3.0     128:612      128:612  20480.5c5eab67e780     20000  FWD    DESG

output from EX4200-1

Interface    Port ID    Designated      Designated         Port    State  Role
                         port ID        bridge ID          Cost
ae0.0            128:1        128:1  16384.28c0da31ce00      5000  FWD    DESG
ge-0/0/0.0     128:513      128:513  16384.28c0da31ce00    200000  FWD    DESG
ge-0/0/3.0     128:516      128:516  16384.28c0da31ce00    200000  FWD    DESG
ge-0/0/13.0    128:526      128:526  16384.28c0da31ce00    200000  FWD    DESG
ge-0/0/14.0    128:527      128:527  16384.28c0da31ce00    200000  FWD    DESG
ge-0/0/15.0    128:528      128:528  16384.28c0da31ce00     20000  FWD    DESG
ge-0/0/45.0    128:558      128:558  16384.28c0da31ce00    200000  FWD    DESG
ge-0/0/46.0    128:559      128:559  16384.28c0da31ce00    200000  FWD    DESG
ge-0/0/47.0    128:560      128:560  16384.28c0da31ce00    200000  FWD    DESG
ge-0/1/0.0     128:609      128:609  16384.28c0da31ce00     20000  FWD    DESG
ge-0/1/1.0     128:610      128:610  16384.28c0da31ce00     20000  FWD    DESG
ge-0/1/2.0     128:611      128:611  16384.28c0da31ce00     20000  FWD    DESG
ge-0/1/3.0     128:612      128:612  16384.28c0da31ce00     20000  FWD    DESG

For the time being we are only runninig the cist instance, and the above is the output for both switches, the ae0 interface has the trunk all vlans and is connecting ex4200-1 to ex4200-2. Spanning tree is very stable as there has been no changes since i finished configuring it, but the problem is both switches are announcing themselves as VRRP master. If i revert back to RSTP the VRRP relationships return back to normal. Its like the connection to ae0 is not there but ae0 is the root port to ex4200-2.

Please help

Also please note that there are some VRRPs that still maintain the original Backup/Master relationship between Ex4200-1 and EX4200-2

Is there a possibility that MSTP is causing the Two switches to treat this ae0 as a layer 3 interface, as this is where my VRRPs are assigned and created.

okay i solved the issue, it was because i had earlier configured flow control on the ae0.0 before i decided to do mstp. i removed it a now we are okay. vrrp is up together with mstp

OK, I THOUGH I HAD SOLVED THE ISSUE BUT AFTER SEVERAL MINUTES THE SAME PROBLEM CAME UP, I HAVE REVERTED BACK TO RSTP, I WILL LOAD BALANCE AT LAYER 3

could the moderators please remove that tick, its misleading

Now , stp or  rstp or mstp  is  used for   loading banlance  layer  2 and    vrrp is used  for  loading banlance  layer 3 .  So ,you can   make them the same time cross.     We always  call that  MSTP+VRRP