[c-nsp] spanning-tree for local switching on ASR920

[Nick Cutting]

Sorry to drag this one up - Gert did you ever get a working config for this?

I plan on using a pair of 920's with a layer 2 broadcast domain on the 12 gigabit Ethernet ports, and using the 10g ports to connect to separate carriers, bust also use 1 10g port to carry the HSRP for the /24 customer address space.
The 1 gig ports will all need to be in the customer's /24 that they will advertise to the independent carriers, I would like run STP in case of a cabling error, but the routers are entirely owned by them, in their data center, and only to be used for ipv4 BGP internet services and a default route from each carrier.

Usually we set this up with a pair of routers and 2 switches - in this case I need to do it all on a ASR-920-12SZ-IM (cheap 10g router)
Is this possible?

Nick

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Gert Doering
Sent: Thursday, October 19, 2017 2:46 AM
To: Peter Rathlev <peter at rathlev.dk>
Cc: Gert Doering <gert at greenie.muc.de>; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] spanning-tree for local switching on ASR920

This Message originated outside your organization.

Hi,

On Thu, Oct 19, 2017 at 06:05:47AM +0200, Peter Rathlev wrote:
> On Wed, 2017-10-18 at 15:39 +0200, Gert Doering wrote:
> > I have an ASR920 that is supposed to have gi0/0/10 and gi0/0/11 in 
> > the same bridge group, with a routed IP:
> > 
> > interface GigabitEthernet0/0/10
> >  no ip address
> >  media-type auto-select
> >  negotiation auto
> >  cdp enable
> >  service instance 10 ethernet
> >   encapsulation untagged
> >   l2protocol peer stp
> >   bridge-domain 10
> >  !
> 
> We don't use STP on ASR920, but my guess is that you need "bridge- 
> domain from-encapsulation" in the service instance configuration.

So where would untagged packets land, then?  "tag 10 -> bridge 10" I could understand, but this is just plain untagged...

> https://www.cisco.com/c/en/us/td/docs/routers/asr920/configuration/gui
> de/lanswitch/lanswitch-xe-3s-asr920-book/lanswitch-xe-3s-asr920-book_c
> hapter_0101.html#task_1000030
> 
> Then configure STP for VLAN "10". It doesn't seem like there is any 
> way to map to an arbitrary PVST instance, VLAN ID and bridge domain ID 
> has to match.

I need to test this :-) - though it feels... weird.

gert


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