REP - usage of STCN command

[leon.mflai]

Hi,

I am working on a POC lab for REP with integration of RSTP of legacy switch. I have a full RSTP ring and 2 x open REP ring. I read certain Cisco document and find a STCN command is needed for "segment topology change notifcation" between REP ring or REP ring with RSTP ring.

However, I found that there is only limited Cisco document for such topics. (only Cisco REP whitepaper or Cisco ME3400 / ME3750 config guide) Would any professional to share any documents (prefer ppt or pdf)

Cheers

Leon

[Laurent Aubert]

HI,

I assume you already read this one: http://www.cisco.com/en/US/prod/collateral/switches/ps6568/ps6580/prod_white_paper0900aecd806ec6fa.pdf

Could you elaborate a little bit on what you are looking for ?

Thanks,

Laurent.

[leon.mflai]

Hi Laurent,  Yes, I hv read this doc.  What I need are configuration example or deployment guide for rep.  I need an example to details what scenario should we apply stcn interface or segment as well as the impact of stcn tsp cmd.  Could u help.?  Tks Leon

[Laurent Aubert]

Hi Leon,

The different option of this command refered to the different topology supported with opened segments (how the 2x Edges switch are connected to the outside world):

- Both edges switches are connected to a STP domain: we need to translate the REP TCN into a STP TCN so the switch in the STP domain can flush their mac addresses as well: rep stcn stp

- Both edges switches are connected to another REP segment: We need to generate a new REP TCN for this new segment: rep stcn segment

- Both edges switches are connected via a common B2B link: There is nothing to propagate but the switch need to fluch the mac addresses learned via this interface: rep stcn interface

In any case, the Admin VLAN (VLAN 1 by default) must be available in the outside world as it is used to send the TCN.

HTH

Laurent.

[leon.mflai]

Hi,

For STCN interface command, What is meaning of B2B link?

Can you send me any configuration example reference for using STCN interface cmd?

For REP admin VLAN, what is the impact and the usage of admin vlan? Is admin VLAN used for the handshake / keepalive msg between REP node?

Tks

Leon Lai

[Laurent Aubert]

B2B link means a direct link between the two switches which doesn't belong to the REP segment.

From http://www.cisco.com/en/US/docs/switches/metro/me3400e/software/release/12.2_52_se/configuration/guide/swrep.html#wp1065752

"REP sends all LSL PDUs in untagged frames on the native VLAN. The BPA message sent to the Cisco multicast address is sent on the administration VLAN, which is VLAN 1 by default."

So bottom-line is if you don't want BPA to be flooded accross the entire L2 domain, you should choose an Admin VLAN which has a limited scope.

The configuration is pretty straightforward: apply the command on your REP edge interface and specify which interface is your common link.

HTH

Laurent.

[pjohannik]

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Laurent,

With regards to the comment - "Both edges switches are connected to another REP segment: We need to generate a new REP TCN for this new segment: rep stcn segment."  If you have multiple segments running in a configuration.  Do you forward the STCN to just the adjacent segments or all segments in the system even though they are not directly connected to the same switch?

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