How many DLCIs can a 7500 support on a DS3 interface?

[randtaylor]

I have about 12 frame-relay T-1s with a total of about 200 DLCIs on a Cisco 7500. I am looking to replace the T-1s with a single DS3 frame port. How many DLCIs can I have on this DS3? Is there a physical limitation on the box or is there a limitation due to a routing protocol's overhead? If there are limitations, should I look at going to ATM Interworking to overcome them in order to have a single DS3 with over 200 PVCs. Thanks.

[donewald]

The limitation is within the Frame Relay DLCI field. This field is 10 bits (until the Exended features to extend this address space) so you are limited to around 1000 DLCI's (some set aside for control functions). You should have no problem with 200 and change PVC's. There are also limits, although much higher, with ATM pvcs as well.

One other thing. If each one of your PVC's will require it's own sub-interface then you'll run into other (IDB Interface Descriptor Block) limitations as well. These are specific to IOS version and platform. The following URL shows these limitations:

http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps1835/products_tech_note09186a0080094322.shtml

Hope this helps you,

Don