P2p self-looped VLAN

[itsystem22]

I have a single trunk on a 3560 connected to a Juniper EX4500 running PVST and the switch is also the root bridge as another 3560 on another port is also connected via a single trunk, both ports are fibre connected, one MM and one SM.

The port to the Juniper, g0/26, has 8 VLANs running through it of which 2 of them are in a P2p self-looped state.  All physical links out of this switch are single links.  There is two ESX hosts but no port-channels only individual trunk links, there are two port-channels to a NetApp SAN with two ports per channel.

On the Juniper I run MSTP but block it at the port level that connects to the Cisco.  I've checked all physical cabling to ensure no loops, also checked the other 3560 just in case.  I have rebooted the switch as well.  The fibre link used has also been changed as there is a 12core fibre between the two locations linking the 3560's.  I haven't moved the SFP to a spare port yet to see if it is a port issue however.

The port to the other 3560 is g0/25.

This is the output of show spanning-tree interface g0/26:

VLAN0001            Desg FWD 4         128.26   P2p
VLAN0006            Desg FWD 4         128.26   P2p
VLAN0010            Desg BLK 4         128.26   P2p self-looped
VLAN0032            Desg FWD 4         128.26   P2p
VLAN0034            Desg BLK 4         128.26   P2p self-looped
VLAN0036            Desg FWD 4         128.26   P2p
VLAN0043            Desg FWD 4         128.26   P2p
VLAN0192            Desg FWD 4         128.26   P2p

I've also looked for other possible devices that may cause this but haven't disconnected either the ESX hosts or NetApp SAN ports, even individual links in case they are the cause.

It started 2 months ago, luckily there is other networks available and the networks having the issue only service one individual however the voice network is affected, vlan0010.

[Reza Sharifi]

Can you post the configs for vlan 10 and 34 from both 3560 and the Juniper 4500?

[itsystem22]

Cisco 3560(not explicitly defined in config)

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
10   voice                            active    Gi0/7, Gi0/8, Gi0/9, Gi0/10
                                                Gi0/11, Gi0/19, Gi0/20, Gi0/21
                                                Gi0/22, Gi0/25, Gi0/26

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
10   enet  100010     1500  -      -      -        -    -        0      0

Remote SPAN VLAN
----------------
Disabled

Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
34   Clients                          active    Gi0/8, Gi0/9, Gi0/10, Gi0/11
                                                Gi0/19, Gi0/20, Gi0/21, Gi0/22
                                                Gi0/25, Gi0/26

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
34   enet  100034     1500  -      -      -        -    -        0      0

Remote SPAN VLAN
----------------
Disabled

Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi0/1, Gi0/2, Gi0/3, Gi0/4
                                                Gi0/12, Gi0/13, Gi0/14, Gi0/17
                                                Gi0/18, Gi0/24, Gi0/27, Gi0/28
6    <name removed>                       active
10   voice                            active    Gi0/7
32   <name removed>                           active    Gi0/7, Gi0/23
34   Clients                          active
36   <name removed>                         active
43   <name removed>                         active
192  <name removed>                            active

Port config(g0/26) to Juniper:

interface GigabitEthernet0/26
 switchport trunk encapsulation dot1q
 switchport mode trunk
 srr-queue bandwidth share 10 10 60 20
 queue-set 2
 priority-queue out
 mls qos trust cos
 auto qos voip trust

Port config to other 3560:

interface GigabitEthernet0/25
 switchport trunk encapsulation dot1q
 switchport mode trunk
 srr-queue bandwidth share 10 10 60 20
 queue-set 2
 priority-queue out
 mls qos trust cos
 auto qos voip trust

Juniper:

clients {
    vlan-id 34;
    l3-interface vlan.34;

family inet {
    address x.x.x.x/23;
}

voice {
    vlan-id 10;
    l3-interface vlan.10;

family inet {
    address y.y.y.y/22;
}

MSTP config: 

set    protocols    mstp    msti 1    bridge-priority    16k
set    protocols    mstp    msti 1    vlan    [voice clients ...]

Interface MSTP protocol config to 3560(mstp disabled):

interface ge-1/0/30.0 {
    disable;

Port configuration link to 3560:

mtu 9216;
unit 0 {
    family ethernet-switching {
        port-mode trunk;
        vlan {
            members [ clients voice ... ];
        }
        native-vlan-id 36;
    }
}

Is there any specific info you are looking for?

I've filtered it for just the two vlans that are in the self-looped mode.

[Reza Sharifi]

Just trying to see if the config for these 2 vlans are different than the other 6 vlans.

So, the 2 switches are connected via a Gig link (0/26).  In this case, there is no need for stp since there is no loop. On the 4500 ge-1/0/30 has mtu of 9216, but don't see the same config on the Cisco switch.

Also does the Juniper do the routing between vlans?

[itsystem22]

The config isn't any different on these vlans than the other 6 vlans.  The switches are connected via g0/26 via a Gig link.  The mtu is 9216 and has been since it was put in production.  There has not been an issue with that as it is the max but will adjust based on my understanding.

The Juniper does the L3 routing for these two networks including many others.

This issue started at a point when no changes had been made for over 3 weeks either config or cabling.