[j-nsp] EX_4500 Dot1q-LAG and MSTP Query !

[Chuck Anderson]

Correcting myself, now that I look at your config more closely, it is
not a L2 VLAN but rather a L3 VLAN config.  I don't think you can run
MSTP with that.  For a L2 MSTP config you would need something like:

set interfaces ae1.0 family ethernet-switching vlan members 3042
set interfaces vlan.3042 family inet address 172.16.0.34/30
set vlans FOO vlan-id 3042
set vlans FOO l3-interface vlan.3042
set protocols mstp interface ae1.0

and then assign all vlans to msti like this across all switches in the
MSTP Region:

set protocols mstp msti 1 vlan x
set protocols mstp msti 1 vlan y
set protocols mstp msti 1 vlan 3042
set protocols mstp msti 2 ...
set protocols mstp msti 2 ...
set protocols mstp msti 3 ...
set protocols mstp msti 3 ...

But I haven't tried a L3 config like yours, so it may work with
MSTP...

On Fri, Jan 27, 2012 at 09:26:27AM -0500, Chuck Anderson wrote:
> On Fri, Jan 27, 2012 at 12:25:18PM +0530, vaibhava varma wrote:
> > In the Juniper EX-4500 series switch if we are using a LAG say ae1 and
> > want to run dot1q peering on it with MX-240 upstreams is it necessary
> > to create the L2 VLAN also in the Switch e.g
> > 
> > set interfaces ae1 vlan-tagging
> > set interfaces ae1 description Interconnection-to-bbsw01-ae1
> > set interfaces ae1.3042 vlan-id 3042
> > set interfaces ae1.3042 description Interconnect_Control_bbsw01
> > set interfaces ae1.3042 family inet address 172.16.0.34/30
> > 
> > Does the VLAN 3042 needs to be added separately in the VLAN Database.
> > My understanding was that is not needed .
> 
> Incorrect, you need to define it in the switch simply like this:
> 
> set vlans FOO vlan-id 3042
> 
> > ALso regarding the MSTP configuration is it mandatory to create all
> > the L2 VLANs in the VLAN Database for which we creating
> > instance-to-vlan mapping.
> 
> No.  You DO have to specify the entire list of VLAN IDs you want to
> associate with each MSTI (this is a requirement of any MSTP switch),
> but you do NOT need to create those VLANs under "edit vlans" unless
> you are going to use them to forward traffic on some interfaces on
> that switch.
> 
> > In a bigger network with lots of switches why do we need to create
> > those L2 VLANS on a Switch for which its not catering any traffic.
> 
> You don't.  You just have to map them to each MSTI so that the MSTP
> Configuration Digest is calculated identically on all switches in the
> entire MSTP Region.  If you don't have a matching digest
> (i.e. matching VLAN <--> MSTI associations for every MSTI) then each
> switch with a different digest will create a boundary and split the
> network into multiple separate MSTP Regions.  You can't load-balance
> VLANs between multiple links across such a boundary.