[c-nsp] Cisco 7600 vlan issue

[Matthew Melbourne]

In article <mailman.1.1227978001.39019.cisco-nsp at puck.nether.net>,
>
> On Fri, Nov 28, 2008 at 07:52:23AM -0800, Mark Tech wrote:
> > Is there anyway around this? I want the 7600 to act like a router, not
> > a switch!
>
> In that case, buy a router, not a switch...
>
> The upside is that the 7600 can do proper ether channels - so if you
> just want to distribute traffic for the same VLAN over multiple GigEs,
> just do an etherchannel and configure the routing on an SVI interface
> (unlike the GSR which is severely limited on what features you can have
> on an etherchannel).
>
> And yes, this is one of the most serious design limitations of the 
> 6500/7600 - "global VLAN space" (with LAN interfaces).  But it's a 
> well-known and well-documented limitation, so usually people know in
> advance and can decide for themselve whether the tremendous price 
> advantage of LAN cards is worth the associated restrictions.
>
> Our decision was: "'real' router interfaces are waaaay too expensive",
> so we live with the restrictions and enjoy the sheer forwarding power :)
>
> gert

Hi,

Can you point me in the direction of any "global VLAN space" documentation
for the Catalyst 6500? The helps to explain why the same dot1q tag
shouldn't be re-used on separate routed sub-interfaces.

e.g. 

interface FastEthernet4/1.100
 encapsulation dot1Q 100
 ip address 10.1.100.1 255.255.255.252
 ip vrf forwarding CUST1
!
interface FastEthernet4/1.101
 encapsulation dot1Q 101
 ip address 10.1.101.1 255.255.255.252
 ip vrf forwarding CUST2
!
!
interface FastEthernet4/2.100
 encapsulation dot1Q 100
 ip address 10.2.100.1 255.255.255.252
 ip vrf forwarding CUST1
!
interface FastEthernet4/2.101
 encapsulation dot1Q 101
 ip address 10.2.101.1 255.255.255.252
 ip vrf forwarding CUST2

I was hoping to re-use VLANs 100/101, as it looks like it should only be
locally significant on the L3 trunk

Cheers,

Matt

-- 
Matthew Melbourne