4507E VSS implementation

[ali16122012]

Dear All,

please help me by answering some questions

in my work we have two different sites each connected to the main office "third site" with dark fiber using Cisco BX SFP "SFP with send and receive over same fiber core but with different wavelength", now i am welling to buy two Cisco 4507E and place one 4507E switch at each site "first and secnod site" and use VSS technology to make these two different site act as one logical site.

My Questions are

1. What Sup i should buy Sup-7 or Sup-8 ?
2. Can VSS come up with one link with 1G speed (not 10G) ?
3. Is BX has any limitation for the above scenario ?
4. If 1G is okay, is it a must to be directly connected link ? 

/Ali

[Leo Laohoo]

What Sup i should buy Sup-7 or Sup-8 ?

Your call.  Both supervisor cards are good.  

Can VSS come up with one link with 1G speed (not 10G) ?

Why bother VSS if you want to do only 1 Gbps.  10 Gbps is ideal because of the traffic flow between the two chassis.  If you're going to be using only 1 Gbps it won't make sense because your VSL will get saturated.

[ali16122012]

Dear Leo.

thanks for your reply, i would like to explain why I want to apply VSS , our current topology include site 1 and site 2 represent two central offices, we have at each central Cisco 7604, all our national service providers are connected to these two Cisco switch, on the other hand our main office "third site" hold a Cisco router connected to the mentioned above switches with dark fiber link for each site, and the main office router configured with different l BGP session with each service provider , for future we will build another two date center beside the one in the main office, what I would like to do is configure VSS between the two central office and build current BGP sessions on the VSS system instead of main office router

finally connect each data center to the two central office 

what do you think I should do

[Leo Laohoo]

VSS doesn't care about how far the two chassis are.  What is the most important part of VSS is that you need to have, a minimum of, two Layer 2 links (fibre preferred).  One link is the heartbeat and the other is the VSL link.  The heartbeat can be 1 Gbps but the VSL link is recommended to be 10 Gbps.  

The logic is the amount of traffic that'll traverse the between the two chassis.  With a 1 Gbps link you'll be guaranteed to saturate this link to cause issues.  

[ali16122012]

which traffic will saturate link, you mean VSS traffic or normal data traffic, as in our current setup one the main office router connected with 1G dark fiber link to each central office and one of these two central offices act as main and the other act as backup and we only utilize 150M of the 1G link and each future data center will be connected to both central offices with STM-1 link and if we need to upgrade we will go with STM-4,

the scenario i was thinking of that i will use direct 1G single core fiber link "BX " to build VSS and if it possible use another single core fiber link "not directly connected, through L2 switch to make the heartbeat" 

my problem is that service providers advertise BGP routes for our customers WAN link "link between each customer router and the his service provider" and i build GRE tunnel between my main office router and the customer's router "managed my me" and route his LAN through this tunnel from my router and route my published servers NAT IPs thruogh tunnel from his router

it was working well, but now we want to build three different data center locations, so i thought to make routing at central offices and connect any new site to these two central offices, but if i put one router at each central office that will make problems

first i will need to double number of GRE tunnels at customer router side

second firewall will need to use dynamic routing protocols instead of static as they now has more than one router to the customer LAN

but with VSS the above two problems is solved as it act as one router

so what do you think