Re: Weired question - same DOT1Q tag on two interfaces on same

Hi Marko,

This is exactly what I was expecting. Excellent answer.

Thanks mate

-kermit

On Sun, Apr 18, 2010 at 10:21 PM, Marko Milivojevic <markom_at_ipexpert.com>wrote:

> Hey there,
>
> This depends on the underlying L2 infrastructure. If it's all the same
> switching domain, then separating broadcast domains is *desirable*.
> Not having it separate could introduce unusual issues and log messages
> - depending on different factors (routing protocols in use, traffic
> being carried, multicast, etc.).
>
> Now, as far as R2 goes, depending on the hardware platform you are
> using, you may or may not be able to use the same VLAN tag on
> different interfaces.
>
> If you are dealing with any decent router (ISR, 7200, 12k, GSR, etc.),
> this is no issue, as VLAN space is local to the interface. In other
> words, you can have traffic tagged as VLAN 10 on Fa0/0 and Fa0/1 and
> it being totally separate as far as R2 is concerned. On the other
> hand, if you are dealing with 6500/7600 swouters which have global
> VLAN space, you may not have te same tag on two separate L3
> subinterfaces... unless you are using "WAN" line cards.
>
> Hth.
>
> --
> Marko Milivojevic - CCIE #18427
> Senior Technical Instructor - IPexpert
>
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>
> On Wed, Apr 14, 2010 at 17:05, Radioactive Frog <pbhatkoti_at_gmail.com>
> wrote:
> > Folks,
> > Here is what I am trying to do.
> >
> > all routers are 2911 or 2811 with routed interface (no switching module
> > ESW).
> >
> > R1------------R2----------R3----------R4
> >
> > Scenario1 - which I always implement:
> > -----------------------------------------
> > R1 - R2 = VLAN 10 - 10.10.10.1/30
> > R2 - R3 = VLAN 20 - 20.20.20.1/30
> > R3 - R4 = VLAN 30 - 30.30.30.1/30
> >
> > Number of VLANs consumed in above scenario:
> > R1 = 1 i.e. fast0/0.10
> > R2 = 2 i.e. fast0/0.10 and fast0/1.20
> > r3 = 2 i.e. fast 0/0.20 and fast0/1.30
> > and so on......
> >
> >
> > To reduce the number of VLAN per router and keep the routing intact can
> we
> > do this?
> >
> > Scenario#2
> > R1 - R2 = VLAN 10 - 10.10.10.1/30
> > R2 - R3 = VLAN 20 - 20.20.20.1/30
> > R3 - R4 = VLAN 30 - 30.30.30.1/30
> >
> > Number of VLANs consumed in above scenario:
> > R1 = 1 i.e. fast0/0.10
> > R2 = 1 i.e. fast0/0.10 and fast0/1.10
> > r3 = 1 i.e. fast 0/0.10 and fast0/1.10
> > and so on......
> >
> > Did you noticed in above case R2 and R3 are only using 2 VLAN ID.
> >
> > I'd be interested to hear from you guys if you see any issue in there
> i.e.
> > using vlan id 10 on R2/R3 both fe0/0 and 0/1 interfaces.
> >
> > Note; No briding, need routing and shoudl be able to use all IOS Feature.
> >
> >
> > The idea is in multi tented environment, we should be able to use vlan ID
> 10
> > for a CUSTOMER1 on all the routers. Having vlan10 on R1 and 20 on r2-r3
> and
> > so on is a bit messy. This approach can also save number of vlan
> consumed
> > and can tanent more customers.
> >
> > I went thr the Dot1q header but not sure how router treat this on
> > interfaces.
> >
> http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtunvlan.html
> >
> > Anyone running this kind of single VLAN in a production environment?
> >
> > -frog
> >
> >
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Received on Tue Apr 20 2010 - 23:47:18 ART