[c-nsp] VLAN Trunking between floors

[Jeff Oliver]

We are wondering how everyone might go about tackling this issue:

We have an Extreme 6808 switch currently handling all our traffic, connected
thru fibre to ISP in their datacenter.  Switch uses Extremeware and the
VLAN's are Extreme proprietary VLAN's, that is not specifically
802.1qtagged VLAN's.

We are moving to another floor of this datacenter and have purchased Cisco
3750's to handle switching in the new cage.  We have already decided to go
with 802.1q VLAN's right off the bat and have designated their VLAN ID's
accordingly.

The new VLAN's exist logically on the Extremes but not in the 802.1q format
- we can however add 802.1q tags to the Extreme VLAN''s without affecting
anything.

Where we get confused is when we want to hook a line between floors with the
entire current setup actually running thru a fibre line up to the new Cisco
gear and then out to the ISP's gear.  We're hoping we can then move load
balanced gear in a staggered fashion without any downtime - that is, the new
load balancer hooked to the Cisco (another trunk port) will be able to see
pool members on the old floor cage thru the magic of VLAN tagging and
trunks.

My thinking is that we take a GBIC on the extreme and hook the inter-floor
line to the Cisco, and then set up an 802.1q trunk with the Cisco, the Cisco
will then see the traffic thru the Extreme and understand the tags as it is
configured at that point to have the same VLAN data.  We then move the
upstream ISP connection to the external, net VLAN off the Cisco and the
Extreme re-arps and finds it's old gateway (the ISP gear) by going through
the Cisco.

My question is basically, am I on the right track?  Are there any obvious
gotcha's or has anyone done anything like this?

Thanks for any thoughts.