MST and Enterasys interoperability

[jskelley]

I am trying to intergrate Cisco switches into to a Enterasys MST network in the lab.

I can match the region  names and change the ROOT between all switches for MST 0 with no problem but not for any other instance other than 0!

For the other instances (11 and 12) the Enterasys kit see's it self as the root as does the primary Cisco switch!

I have changed priorities on numerous switches to try and see if I can spot a change but can not.

Has anyone seen this before, am I missing a simple command on the Entersys or Cisco kit to get over the vlan 1 (MST0) tag issue or is it something more simple I am just missing?

Thanks in advance for any info.

[Peter Paluch]

Hello,

This is an interesting problem indeed. It seems as if Cisco and the Enterasys were in different regions. The IST (MSTI 0) is propagated between regions but other instances remain limited to their regions and each of them has its own regional root. This seems to correlate to your findings.

Please check the show spanning-tree command output on Cisco switch connected to the Enterasys and look for any ports described as Bound (boundary) ports. If you see any such ports then that confirms that your Cisco and the Enterasys are in different regions.

Note that for two MSTP switches to be in the same region, all three following configuration elements must match:

1. region name
2. revision number
3. VLAN-to-instance mapping

Please double check these settings.

Best regards,

Peter

[jskelley]

Hi Peter

Here is the Enterasys MST configs:

C2(rw)->show spantree mstilist

Configured Multiple Spanning Tree Instances:

11 12

C2(rw)->show spantree mstcfgid

MST Configuration Identifier:

Format Selector:    0

Configuration Name: LKS

Revision Level:     1

Configuration Digest:c8:02:17:44:25:20:9e:ea:66:13:94:79:6a:f4:c5:96

C2(rw)->

C2(rw)->show spantree mstmap

Fid  11 is mapped to Sid 11

Fid  12 is mapped to Sid 12

Fid  13 is mapped to Sid 12

C2(rw)->

C2(rw)->

--------,snip from show config----------

#spantree

set spantree mstcfgid cfgname 'LKS' rev 1

set spantree msti sid 11 create

set spantree msti sid 12 create

set spantree mstmap 11 sid 11

set spantree mstmap 12 sid 12

set spantree mstmap 13 sid 12

set spantree priority 0 0

set spantree priority 0 11

set spantree priority 0 12

!

--------------end----------------

and here is the Cisco 3550 config:

SWITCH_1#sh spanning-tree mst configuration

Name      [LKS]

Revision  1

Instance  Vlans mapped

--------  ---------------------------------------------------------------------

0         1-10,14-4094

11        11

12        12-13

-------------------------------------------------------------------------------

SWITCH_1#sh spanning-tree mst detail

###### MST00        vlans mapped:   1-10,14-4094

Bridge      address 000d.bc43.7780  priority  24576 (24576 sysid 0)

Root        address 0001.f45d.ec74  priority  0     (0 sysid 0)

            port    Fa0/1           path cost 200000  

IST master  this switch

Operational hello time 2, forward delay 15, max age 20

Configured  hello time 2, forward delay 15, max age 20, max hops 20

FastEthernet0/1 of MST00 is root forwarding

Port info             port id          128.1  priority    128  cost      200000

Designated root       address 0001.f45d.ec74  priority      0  cost           0

Designated ist master address 000d.bc43.7780  priority  24576  cost           0

Designated bridge     address 0001.f45d.ec74  priority      0  port id    128.1

Timers: message expires in 5 sec, forward delay 0, forward transitions 1

Bpdus sent 915, received 455

FastEthernet0/2 of MST00 is designated forwarding

Port info             port id          128.2  priority    128  cost      200000

Designated root       address 0001.f45d.ec74  priority      0  cost      200000

Designated ist master address 000d.bc43.7780  priority  24576  cost           0

Designated bridge     address 000d.bc43.7780  priority  24576  port id    128.2

Timers: message expires in 0 sec, forward delay 0, forward transitions 2

Bpdus sent 510, received 10

###### MST11        vlans mapped:   11

Bridge      address 000d.bc43.7780  priority  24587 (24576 sysid 11)

Root        this switch for MST11

FastEthernet0/1 of MST11 is boundary forwarding

Port info             port id          128.1  priority    128  cost      200000

Designated root       address 000d.bc43.7780  priority  24587  cost           0

Designated bridge     address 000d.bc43.7780  priority  24587  port id    128.1

Timers: message expires in 0 sec, forward delay 0, forward transitions 1

Bpdus (MRecords) sent 917, received 0

FastEthernet0/2 of MST11 is designated forwarding

Port info             port id          128.2  priority    128  cost      200000

Designated root       address 000d.bc43.7780  priority  24587  cost           0

Designated bridge     address 000d.bc43.7780  priority  24587  port id    128.2

Timers: message expires in 0 sec, forward delay 0, forward transitions 1

Bpdus (MRecords) sent 511, received 10

###### MST12        vlans mapped:   12-13

Bridge      address 000d.bc43.7780  priority  32780 (32768 sysid 12)

Root        this switch for MST12

FastEthernet0/1 of MST12 is boundary forwarding

Port info             port id          128.1  priority    128  cost      200000

Designated root       address 000d.bc43.7780  priority  32780  cost           0

Designated bridge     address 000d.bc43.7780  priority  32780  port id    128.1

Timers: message expires in 0 sec, forward delay 0, forward transitions 1

Bpdus (MRecords) sent 919, received 0

FastEthernet0/2 of MST12 is designated forwarding

Port info             port id          128.2  priority    128  cost      200000

Designated root       address 000d.bc43.7780  priority  32780  cost           0

Designated bridge     address 000d.bc43.7780  priority  32780  port id    128.2

Timers: message expires in 0 sec, forward delay 0, forward transitions 1

Bpdus (MRecords) sent 512, received 10

SWITCH_1#

-----------end-----------------

As I can show here the MST0 0n the 3550 can see .ec74 as the ROOT but not for the other instance even with .ec74 priority set to 0 for all instances.  As best I can tell the name, rev and mappings are the same.

Any ideas or help much appreciated.

Thanks

J

[Peter Paluch · Accepted solution]

Hello J,

It indeed seems that your Cisco and Enterasys are partitioned into different MSTP regions. From the output of show spanning-tree mst detail:

FastEthernet0/1 of MST11 is boundary forwarding

FastEthernet0/1 of MST12 is boundary forwarding

The region configuration appears to be identical. However, what I do not see is where are the VLANs 1-10,14-4094 mapped on the Enterasys switches. The output of show spantree mstmap shows us the mappings for VLANs 11-13 but I do not see any indication of VLAN mappings into the MSTI 0. Are they certainly mapped to MSTI 0 on Enterasys?

A helpful indication is the configuration digest. This is a MD5 digest of the VLAN-to-instance mapping, and is carried in MST BPDUs. Obviously, it must match between switches in the same region. The Enterasys reports it as:

Configuration Digest:c8:02:17:44:25:20:9e:ea:66:13:94:79:6a:f4:c5:96

Can you please issue the show span mst config digest command on the Catalyst and post the output here? Thanks!

Best regards,

Peter

[jskelley]

Hi Peter

Thanks for your help on this.  This appears to be a hidden command on the ver of IOS I am running! 

As you say the do match on the two Cisco switches which operate fine but not on the Enterasys!

Thanks

J

SWITCH_1#sh spanning-tree mst config digest

Name      [LKS]

Revision  1

Instance  Vlans mapped

--------  ---------------------------------------------------------------------

0         1-10,14-4094

11        11

12        12-13

-------------------------------------------------------------------------------

Digest    FC6C23DB8E234B7F0E34E1CC895BC511

SWITCH_1#

-----------------The other Cisco switch----------------------

SWITCH_2#sh span mst config dige

Name      [LKS]

Revision  1

Instance  Vlans mapped

--------  ---------------------------------------------------------------------

0         1-10,14-4094

11        11

12        12-13

-------------------------------------------------------------------------------

Digest    FC6C23DB8E234B7F0E34E1CC895BC511

SWITCH_2#

[jskelley]

Hi Peter

Thank you very much for your input.

I upgrade the IOS on the 3550's and can not see the correct root!!

If you had not shown me that command, it made me realise if I was running IOS with hidden commands a upgrade was needed.  This is the new ver output:

SWITCH_1#sh spanning-tree mst configuration ?

  digest  Display MST configuration digest

  |       Output modifiers

SWITCH_1#sh spanning-tree mst configuration digest

Name      [LKS]

Revision  1     Instances configured 3

Digest          0xC802174425209EEA661394796AF4C596

Pre-std Digest  0xFC6C23DB8E234B7F0E34E1CC895BC511

SWITCH_1#

SWITCH_1#sh spanning-tree mst

##### MST0    vlans mapped:   1-10,14-4094

Bridge        address 000d.bc43.7780  priority      24576 (24576 sysid 0)

Root          address 0001.f45d.ec74  priority      0     (0 sysid 0)

              port    Fa0/1           path cost     0       

Regional Root address 0001.f45d.ec74  priority      0     (0 sysid 0)

                                      internal cost 200000    rem hops 19

Operational   hello time 2 , forward delay 15, max age 20, txholdcount 6

Configured    hello time 2 , forward delay 15, max age 20, max hops    20

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/1            Root FWD 200000    128.1    P2p

Fa0/2            Desg FWD 200000    128.2    P2p

Fa0/3            Desg FWD 200000    128.3    P2p Edge

##### MST11   vlans mapped:   11

Bridge        address 000d.bc43.7780  priority      24587 (24576 sysid 11)

Root          address 0001.f45d.ec74  priority      11    (0 sysid 11)

              port    Fa0/1           cost          200000    rem hops 19

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/1            Root FWD 200000    128.1    P2p

Fa0/2            Desg FWD 200000    128.2    P2p

##### MST12   vlans mapped:   12-13

Bridge        address 000d.bc43.7780  priority      32780 (32768 sysid 12)

Root          address 0001.f45d.ec74  priority      12    (0 sysid 12)

              port    Fa0/1           cost          200000    rem hops 19

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/1            Root FWD 200000    128.1    P2p

Fa0/2            Desg FWD 200000    128.2    P2p

SWITCH_1#

------------------------Enteraysy-----------------------------------------

C2(rw)->show spantree mstcfgid

MST Configuration Identifier:

Format Selector:    0

Configuration Name: LKS

Revision Level:     1

Configuration Digest:c8:02:17:44:25:20:9e:ea:66:13:94:79:6a:f4:c5:96

C2(rw)->

-----------------------end--------------------------------------

As you can see I can now see the correct MST operation!

Thanks again Peter for all your help.

Regards

J

[Peter Paluch]

Hello J,

I am glad you have resolved this issue! The show span mst config digest was a hidden command in older IOS versions but it it an official and documented command now. Even the old 2950 support it - although they also treat it as hidden.

I now know what has happened. Your previous IOS version was running a so-called pre-standard MST version. Cisco started implementing the MST before the 802.1s was finalized. The format of BPDUs between the pre-standard and the official 802.1s is slightly modified. As your Catalyst spoke to the Enterasys using the pre-standard MST, the Enterasys did not entirely understand it, and basing on differing MD5 hash, both switches have declared they're in different regions. You can also see that the older IOS produced just a single MD5 hash while the new IOS produces two hashes - one for the pre-standard MST and the other for the standard 802.1s.

Anyway, thanks for letting me know

Best regards,

Peter

[cajunsausage]

I'm having this exact same problem. My difference is that I'm using Cisco 9300s and 3850 s that have been added to my Enterasys network. I have the same problem literally as stated above, other than the fact that my configuration digest matches on the enterasys and on The Ciscos. The only differences that I can spot are that, as stated in the previous part of this problem, the default Cisco vlans that are automatically configured are not part of my enterasys network. So when I show the MST map, it does not show those default vlans that are automatically created on Cisco switches. It took me a little while to realize that my enterasys switches had all been misconfigured for mstp, so once I actually got them all configured correctly, they now all talk correctly across all 3 of my instances 0, 10, and 20. In the mean time I had to change the ciscos back to Rstp so they'd work. Once I put the configuration back into the Ciscos and change them from Rapid to MST, Rather than seeing the root bridge as my core S3, they were showing other Cisco switches as the roots for instance 10 and 20, even though the S3 has the lowest priority for each of the instances. I'm totally baffled. Any ideas on how I can find out why the Ciscos are not talking correctly via mstp with the enterasys, even though they have the same revision number, region name, and from what I can tell same VLAN instance mapping, and configuration digest number?