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MSTP between Cisco / Brocade

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sraymond at acedatacenter

Apr 25, 2012, 1:52 PM

Post #1 of 7 (1065 views)
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MSTP between Cisco / Brocade

Have a single layer 2 connection between 7609, version 12.2(33)SRD4, 6708, with a 10G connection to Brocade. Using simplest form of MSTP, it works "fine" to a Brocade TI24X switch, running version 4 something.

Move the same cable to a 10G port on a MLXe, version 5.2.0T165, the Cisco blocks the port as the following:

ar01.prov#show spanning-tree active detail
Port 4 (TenGigabitEthernet1/4) of MST0 is designated blocking (dispute)
Port path cost 2000, Port priority 128, Port Identifier 128.4.
Designated root has priority 16384, address 0015.62b7.0dc0
Designated bridge has priority 16384, address 0015.62b7.0dc0
Designated port id is 128.4, designated path cost 0
Timers: message age 0, forward delay 14, hold 0
Number of transitions to forwarding state: 0
Link type is point-to-point by default, Internal
BPDU: sent 20540, received 10287

Google suggests that this may be caused by both switches' ports declaring they are designated role for the segment, and the Cisco proceeds to block as a defense against uni-directional link. But these same optics and cables work fine on the other device. Even so, they have been swapped with same circumstance. Am certain there is no uni-directional link here.

Other searching says that Cisco is bad and sends the BPDUs tagged and that native vlan tagging must be removed, which is not enabled to begin with.

Brocade said to add "pvst-mode" to the interface config on the MLXe side, but it did not help at all. And I don't understand what PVST has to do with MSTP as currently configured.

Any suggestions?

Thanks!!

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randy_94108 at yahoo

Apr 25, 2012, 2:55 PM

Post #2 of 7 (1029 views)
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Re: MSTP between Cisco / Brocade [In reply to]

--- On Wed, 4/25/12, Steven Raymond <sraymond [at] acedatacenter> wrote:

> From: Steven Raymond <sraymond [at] acedatacenter>
> Subject: [c-nsp] MSTP between Cisco / Brocade
> To: "cisco-nsp Service Providers" <cisco-nsp [at] puck>
> Date: Wednesday, April 25, 2012, 1:52 PM
> Have a single layer 2 connection
> between 7609, version 12.2(33)SRD4, 6708, with a 10G
> connection to Brocade. Using simplest form of MSTP, it
> works "fine" to a Brocade TI24X switch, running version 4
> something.
>
> Move the same cable to a 10G port on a MLXe, version
> 5.2.0T165, the Cisco blocks the port as the following:
>
> ar01.prov#show spanning-tree active detail
> Port 4 (TenGigabitEthernet1/4) of MST0 is designated
> blocking (dispute)
>    Port path cost 2000, Port priority 128,
> Port Identifier 128.4.
>    Designated root has priority 16384,
> address 0015.62b7.0dc0
>    Designated bridge has priority 16384,
> address 0015.62b7.0dc0
>    Designated port id is 128.4, designated
> path cost 0
>    Timers: message age 0, forward delay 14,
> hold 0
>    Number of transitions to forwarding state:
> 0
>    Link type is point-to-point by default,
> Internal
>    BPDU: sent 20540, received 10287
>
> Google suggests that this may be caused by both switches'
> ports declaring they are designated role for the segment,
> and the Cisco proceeds to block as a defense against
> uni-directional link. But these same optics and cables
> work fine on the other device. Even so, they have been
> swapped with same circumstance. Am certain there is no
> uni-directional link here.
>
> Other searching says that Cisco is bad and sends the BPDUs
> tagged and that native vlan tagging must be removed, which
> is not enabled to begin with.
>
> Brocade said to add "pvst-mode" to the interface config on
> the MLXe side, but it did not help at all. And I don't
> understand what PVST has to do with MSTP as currently
> configured.
>
> Any suggestions?
>
> Thanks!!

...I haven't played with Foundry/Brocade for a while.

It is clear that on the Cisco you have "enabled" 802.1s(MISTP)

I am not clear if you have 802.1s OR 802-1w enabled on the Brocade(care to post the stp output from Brocade?)

I ask because in the past Brocade/Foundry referred to 802.1W(R-PVST in Cisco-speak) as MULTIPLE-SPANNING-TREE!

./Randy

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sraymond at acedatacenter

Apr 25, 2012, 3:03 PM

Post #3 of 7 (1030 views)
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Re: MSTP between Cisco / Brocade [In reply to]

On Apr 25, 2012, at 3:55 PM, Randy wrote:

> I am not clear if you have 802.1s OR 802-1w enabled on the Brocade(care to post the stp output from Brocade?)

sh run | i mstp
mstp name acedc
mstp revision 1
mstp instance 0 vlan 1 to 4090
mstp start

telnet [at] ar04#show mstp detail
MSTP Instance 0 (CIST) - VLAN Scope: 1 to 4090
----------------------------------------------------------------------------
Bridge: 80000024389c3d00 [Priority 32768, SysId 0, Mac 0024389c3d00]
FwdDelay 15, HelloTime 2, MaxHops 20, TxHoldCount 6

Port 2/1 - Role: DESIGNATED - State: FORWARDING
PathCost 2000, Priority 128, OperEdge T, OperPt2PtMac F, Boundary N/A
Designated - Root 80000024389c3d00, RegionalRoot 80000024389c3d00,
Bridge 80000024389c3d00, ExtCost 0, IntCost 0
ActiveTimers - helloWhen 2
MachineState - PRX-DISCARD, PTX-IDLE, PPM-SENDING_RSTP, PIM-CURRENT
PRT-ACTIVE_PORT, PST-FORWARDING, TCM-INACTIVE
BPDUs - Rcvd MST 0, RST 0, Config 0, TCN 0
Sent MST 11, RST 0, Config 0, TCN 0

telnet [at] ar04#sh spanning-tree
telnet [at] ar04#show rstp
telnet [at] ar04#

That helpful?

Thanks!

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randy_94108 at yahoo

Apr 25, 2012, 4:08 PM

Post #4 of 7 (1034 views)
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Re: MSTP between Cisco / Brocade [In reply to]

--- On Wed, 4/25/12, Steven Raymond <sraymond [at] acedatacenter> wrote:

From: Steven Raymond <sraymond [at] acedatacenter>
Subject: Re: [c-nsp] MSTP between Cisco / Brocade
To: "Randy" <randy_94108 [at] yahoo>
Cc: "cisco-nsp Service Providers" <cisco-nsp [at] puck>
Date: Wednesday, April 25, 2012, 3:03 PM

On Apr 25, 2012, at 3:55 PM, Randy wrote:

I am not clear if you have 802.1s OR 802-1w enabled on the Brocade(care to post the stp output from Brocade?)

sh run | i mstp

mstp name acedc
mstp revision 1
mstp instance 0 vlan 1 to 4090
mstp start

telnet [at] ar04#show mstp detail
MSTP Instance 0 (CIST) - VLAN Scope: 1 to 4090
----------------------------------------------------------------------------
Bridge: 80000024389c3d00 [Priority 32768, SysId 0, Mac 0024389c3d00]
FwdDelay 15, HelloTime 2, MaxHops 20, TxHoldCount 6

Port 2/1 - Role: DESIGNATED - State: FORWARDING
PathCost 2000, Priority 128, OperEdge T, OperPt2PtMac F, Boundary N/A
Designated - Root 80000024389c3d00, RegionalRoot 80000024389c3d00,
Bridge 80000024389c3d00, ExtCost 0, IntCost 0
ActiveTimers - helloWhen 2
MachineState - PRX-DISCARD, PTX-IDLE, PPM-SENDING_RSTP, PIM-CURRENT
PRT-ACTIVE_PORT, PST-FORWARDING, TCM-INACTIVE
BPDUs - Rcvd MST 0, RST 0, Config 0, TCN 0
Sent MST 11, RST 0, Config 0, TCN 0

telnet [at] ar04#sh spanning-tree
telnet [at] ar04#show rstp
telnet [at] ar04#

That helpful?

Thanks!

Yes & No.
Yes: both devices are running 802.1s

No: Because of outputs posted:

Output from Brocade-above:
"Bridge: 80000024389c3d00 [Priority 32768, SysId 0, Mac 0024389c3d00]"

Output from Cisco:
Port 4 (TenGigabitEthernet1/4) of MST0 is designated
blocking (dispute)
Port path cost 2000, Port priority 128,
Port Identifier 128.4.
Designated root has priority 16384,
address 0015.62b7.0dc0
Designated bridge has priority 16384,
address 0015.62b7.0dc0

Who is:

0015.62b7.0dc0 with a bridge-priority of 16384?

That is the "who" the cisco is blocking.

From Brocade-output above:

Bridge: 80000024389c3d00 [Priority 32768, SysId 0, Mac 0024389c3d00]

./Randy
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sraymond at acedatacenter

Apr 26, 2012, 12:09 PM

Post #5 of 7 (1013 views)
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Re: MSTP between Cisco / Brocade [In reply to]

On Apr 25, 2012, at 5:08 PM, Randy wrote:

> Who is:
>
> 0015.62b7.0dc0 with a bridge-priority of 16384?
>
> That is the "who" the cisco is blocking.
>
> From Brocade-output above:
>
> Bridge: 80000024389c3d00 [Priority 32768, SysId 0, Mac 0024389c3d00]
>
> ./Randy

The mac in question is the Cisco's:
ar01.prov#sh spanning-tree active

MST0
Spanning tree enabled protocol mstp
Root ID Priority 16384
Address 0015.62b7.0dc0
This bridge is the root

But nevermind I suppose, the issue is resolved with help from Brocade TAC. The MLX defaults to "route-only" which apparently means every port acts like Cisco's equivalent to "no switchport" or layer-3 only mode. So it would receive the MLX's BPDUs and silently discard them. Here's the strange part, despite being set for "route-only", the MLX still transmits BPDUs. Which the Cisco received, detected that the MLX said port role is "designated", and put it into blocking dispute since Cisco is the real root.

Is it common & expected for swouters to tx BPDUs when the port is in layer-3-only mode? Or am I just not getting the idea behind "route-only" in Brocade?

Thanks for the help!

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sraymond at acedatacenter

Apr 26, 2012, 12:28 PM

Post #6 of 7 (1014 views)
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Re: MSTP between Cisco / Brocade [In reply to]

On Apr 26, 2012, at 1:09 PM, Steven Raymond wrote:

> The MLX defaults to "route-only" which apparently means every port acts like Cisco's equivalent to "no switchport" or layer-3 only mode. So it would receive the MLX's BPDUs and silently discard them.

s/receive the MLX's/receive the Cisco's/

Meh my crappy proofreading.

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sthaug at nethelp

Apr 26, 2012, 12:48 PM

Post #7 of 7 (1003 views)
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Re: MSTP between Cisco / Brocade [In reply to]

> Is it common & expected for swouters to tx BPDUs when the port is in layer-3-only mode? Or am I just not getting the idea behind "route-only" in Brocade?

I would definitely not expect a routed interface to transmit BPDUs
by default.

Steinar Haug, Nethelp consulting, sthaug [at] nethelp
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