Ethernet Switches & Routers

Reply
New Contributor
Posts: 4
Registered: ‎11-02-2010

Spanning-tree mode

Anyone has strange experience between rapid-pvst (cisco) and pvst+ (brocade) set up?

thanks,

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: Spanning-tree mode

if you can change the CISCO to PVST+ you may find the "stangness" go away.

For explame PVST will not interop with 802.1Q devices but PVST+ will.

So if you have a mix and match of different Spanning three type in your network you should look at using MSTP as that is what this standard addresses.

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Spanning-tree mode

Hi There,
I had similar issue in an environment where two 4500s, two TurboIrons and two FWSs are connected as below:Untitled.jpg

PVST configured on the 4500s, MSTP configured on the brocade switches and when there were about 150 vlans we did not see any topology change for STP. (first 4500 was the root switch for all vlans.)
Adding more vlans after a while all traffic was interrupted for some time that we had to disable link 7,8 and 10 in order to make service up immediately.

in terms of STP ciscos are configured as below:

4510R-E

spanning-tree mode pvst

spanning-tree extend system-id

spanning-tree vlan 1-4096 priority 4096

4507R-E

spanning-tree mode pvst

spanning-tree extend system-id

spanning-tree vlan 1-4094 priority 28672

and MSTP configured under all vlans for brocade switches. (spanning-tree priority 65500) only one port of one turboiron which is connected to 4500 is automatically configured to PVST.Do you think there might be a mistake when adding vlans or it is better to change cisco PVST configuration to MST or brocade MST configuration to PVST/PVST+. and additionally what about single spanning tree configuration? STP convergence is more important than stp load balance here so we may think about  to configure single STP instance for all vlans. I appreciate if you can send your comments & suggestions.

Thanks & Regards,

Serhat

Frequent Contributor
Posts: 117
Registered: ‎07-26-2010

Re: Spanning-tree mode

Hi Serhat,

as far as I know and have seen in my customer networks and lab tests, MSTP and Cisco PVST(+) are not interoperable.

MSTP only sends one single BPDU to dest mac 0180c2000000 including the MSTP information (region, revision, config digest).

Cisco PVST sends a BPDU per VLAN, but only for the natvive Port VLAN the BPDU is sent to the standard MAC 0180c2000000. The BPDUs for all other VLANs is a Cisco proprietary 01xxxxxx MAC.

From my experience the best combination for interworking would be MSTP on Brocade and Cisco.

Since you have mentioned something about 150 VLANs I would not run a Per VLAN Spnnaing Tree on the Brocade boxes, since I have too often run into CPU issues with so many STP processes, one for each VLAN.

My suggestion is:

-- do a good pre-planning on your MSTP with a good VLAN to instance pre-mapping

-- run MSTP in Cisco and Brocade

Hope this helps

Karl

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Spanning-tree mode

Hi Karl,

First of all a very thanks for your fast response and for your recommendations.
I also wonder how it worked until last week and what was the reason for this interruption.
What I know is adding vlans does not affect native vlan connection between switches.
I belive there was a flap between Turboiron and Cisco and when TI missed some BPDUs
they all  started to look for a new root bridge.
Another  assumption is that TI passed some large traffic from its 10G to 1G port which fills  receive buffer.
Because I saw some indiscards  on turboirons.

Turboiron 1

Port 1 Counters:

       InDiscards             94110086           OutErrors                    0

           

Port 25 Counters:

       InDiscards           3185866790           OutErrors                    0

Port 26 Counters:

       InDiscards           3216620777           OutErrors                    0


Turboiron 2

Port 1 Counters:

       InDiscards             50857839           OutErrors                    0

Do you think this indiscards are the reason of STP topology change or they are the result of this interruption.


Serhat

Frequent Contributor
Posts: 117
Registered: ‎07-26-2010

Re: Spanning-tree mode

Hi Serhat,

"some" indiscards... well I think this are pretty very much indiscards.

I have never seen this amount or even any Indiscards at my customers with TIs.

There might have been drop situations for BPDUs also.

But since RSTP a switch has to miss 3 BPDUs (3x2s = 6s) to declare a STP neighbor as down.

Do you have a syslog server?

If yes, check for New Root messages?

regards

Karl

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Spanning-tree mode

Hi Karl,

Here are the logs form one of the switches:

09:04:31        192.168.16.67    Informational    C-11-a STP: VLAN 2156 Bridge is RootBridge: ffff0024XXXXfc40 (MsgAgeExpiry)

09:04:01        192.168.16.67    Informational    C-11-a STP: VLAN 2156 Bridge is RootBridge: ffff0024XXXXfc40 (MsgAgeExpiry)

09:00:18        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/5 (BpduRcvd)

08:59:34        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/5 (BpduRcvd)

08:52:55        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/5 (BpduRcvd)

08:52:41        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/5 (BpduRcvd)

08:52:41        192.168.16.67    Informational    C-11-a STP: VLAN 2156 Bridge is RootBridge: ffff0024XXXXfc40 (MsgAgeExpiry)

08:51:11        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/5 (BpduRcvd)

08:50:51        192.168.16.67    Informational    C-11-a STP: VLAN 2156 Bridge is RootBridge: ffff0024XXXXfc40 (MsgAgeExpiry)

08:48:48        192.168.16.67    Informational    C-11-a STP: VLAN 2156 Bridge is RootBridge: ffff0024XXXXfc40 (MsgAgeExpiry)

08:47:45        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/5 (BpduRcvd)

08:43:20        192.168.16.67    Informational    C-11-a STP: VLAN 2156 New RootBridge: 686c001fXXXXe880 RootPort: 0/1/6 (BpduRcvd)


I appreciate if you can suggest me about configuring Spanning-Tree Signle on brocade devices while leaving PVST configuration as it is on Ciscos.
I mean how should brocades be configured if ciscos have to run PVST  and it is not recommended to configure PVST on brocade for that amount of VLANs. There are two main questions:

Can brocades work with single STP when one of the ciscos is root and they have PVST
Do we need to  disable PVST on turboiron port (which is connected to cisco) which is configured automatically to PVST


Best Regards,

Serhat

Frequent Contributor
Posts: 117
Registered: ‎07-26-2010

Re: Spanning-tree mode

Hi Serhat,

(MsgAgeExpiry) shows that the switch missed to receive BPDUs and aged the STP neighbor.

You could check the manual on SSTP...

Single Spanning Tree (SSTP)

Alternatively, you can configure a Brocade device to run a single spanning tree across all ports and

VLANs on the device. The Single STP feature (SSTP) is especially useful for connecting a Brocade

device to third-party devices that run a single spanning tree in accordance with the 802.1Q

specification.

SSTP uses the same parameters, with the same value ranges and defaults, as the default STP

support on Brocade devices. Refer to

“STP parameters and defaults”

on page 263.

Enabling SSTP

To enable SSTP, use one of the following methods.

NOTE

If the device has only one port-based VLAN (the default VLAN), then the device is already running a

single instance of STP. In this case, you do not need to enable SSTP. You need to enable SSTP only

if the device contains more than one port-based VLAN and you want all the ports to be in the same

STP broadcast domain.

To configure the Brocade device to run a single spanning tree, enter the following command at the

global CONFIG level.

FastIron(config)#spanning-tree single

NOTE

If the device has only one port-based VLAN, the CLI command for enabling SSTP is not listed in the

CLI. The command is listed only if you have configured a port-based VLAN.

To change a global STP parameter, enter a command such as the following at the global CONFIG

level.

Join the Community

Get quick and easy access to valuable resource designed to help you manage your Brocade Network.

vADC is now Pulse Secure
Download FREE NVMe eBook