Frame Relay top speed 1.54 Mbps?

Hi, As I undersand the Maximum Bandwith for ATM Service is 622 Mbps, though higher speeds are being developed. Typical media used are Twisted pair and Optical Fiber. hope that helps, CraftWorks.

sounds like another old USA tunnel vision Q.

FWIW the typical port speed in Europe was "up to 2 Mbps" (E1) and F/R is covered by world wide standards - so 1.5 was a USA only answer....

F/R was also available here at E3 34 Mbps as a service from some telcos - but european telco F/R networks typically used ATM above 2 Mbps.

However - if you ignore the "switching" bit of Frame Relay in the telco cloud, then from a router perspective F/R is just a serial encapsulation choice.

And in a Cisco router which supports the interfaces, it works on high speed serial interfaces such as HSSI (50 Mbps), as well as some others such as E3 / T3 ports.

starting to learn CCNA, go easy on me :)

Great question-so to conclude FR is capable of whatever speed the I/F can support?

starting to learn CCNA, go easy on me :)

as long as it is a serial port that support F/R encapsulation, then yes.

we use it at work to do multi VRF to a CE router from MPLS - in this case there is no switch, just PVCs defined on a CE and a PE to give different sub interfaces to keep the traffic flows segregated.

fastest one i know about is HSSI, which can do around 50 Mbps - but that doesnt mean there arent other flavours...

WOuld ATM use FR>? I read that it supports speeds up to 150mb. I know it uses cells...

ATM is a different format "on the wire", but many F/R switches are actually hybrid F/R + ATM.

If you are using ATM as a data network format, then some frame & ATM formats are compatible, and you can have a PVC that is F/R at 1 end (maybe for low bandwidth since ATM isnt used on lines below 2 Mbps), but with ATM into central site routers.

AFAIR last switches @ work were Alcatel 7670s (these come from the Newbridge Networks product suite that Alcatel bought up). They are ATM internally, but support F/R as an interface.

Cisco had a similar set of switches - now obsolete. Lightstream 1010s?

Finally ATM can go a lot faster than 155 Mbps if you had the right kit -

Thats fast! Thanks for the information-much appreciated.

T1 line.

Take this in the mindset of the OSI model: (3) Network (2) Data Link (1) Physical Frame-Relay and ATM are both layer 2 data-link technologies, just like Ethernet, Token-Ring, PPP, and HDLC. It is common to see WAN connections as T1 (a.k.a. DS-1) lines which are 1.5mb/s. This is probably the source of the misconception. Seperate the layer 2 frame-relay technology from the layer 1 circuit technologu that it commonly runs on.

You can have a fractional T-1 with speeds of 256k, 384k, etc... You can combine T-1 lines with speeds totallying 3m, 4.5m, 6m, etc.. No matter which combination is used, the layer 2 signaling can be PPP, HDLC, frame-relay, ATM, etc... Most of the time, the telco will provide lines at certian speeds. Yes, ATM is commonly used for faster lines. Yes, Frame-Relay is usually not found above 1.5mb/s.

EXAMPLE: Situation #1 - PPP A single T-1 line is run directly between two office locations. RouterA(config)# interface serial 0 RouterA(config-if)# encapsulation ppp RouterA(config-if)# ip address RouterB(config)# interface serial 0 RouterB(config-if)# encapsulation ppp RouterB(config-if)# ip address Situation #2 - HDLC A single T-1 line is run directly between two office locations. RouterA(config)# interface serial 0 RouterA(config-if)# encapsulation hdlc RouterB(config-if)# ip address RouterB(config)# interface serial 0 RouterB(config-if)# encapsulation hdlc RouterB(config-if)# ip address Situation #3 - Frame-Relay Two T-1 lines are run between two office locations with the telco providing a frame-relay switch in between. RouterA(config)# interface serial 0 RouterA(config-if)# encapsulation frame-relay RouterA(config)# interface serial 0.1 RouterA(config-if)# ip address RouterA(config-if)# frame-relay interface-dlci RouterB(config)# interface serial 0 RouterB(config-if)# encapsulation frame-relay RouterB(config)# interface serial 0.1 RouterB(config-if)# ip address RouterB(config-if)# frame-relay interface-dlci

Situation #4 - Frame-Relay Three T-1 line are run between three office locations with the telco providing a frame-relay switch in between. RouterA(config)# interface serial 0 RouterA(config-if)# encapsulation frame-relay RouterA(config)# interface serial 0. RouterA(config-if)# ip address RouterA(config-if)# frame-relay interface-dlci RouterB(config)# interface serial 0 RouterB(config-if)# encapsulation frame-relay RouterB(config)# interface serial 0. RouterB(config-if)# ip address RouterB(config-if)# frame-relay interface-dlci RouterC(config)# interface serial 0 RouterC(config-if)# encapsulation frame-relay RouterC(config)# interface serial 0. RouterC(config-if)# ip address RouterC(config-if)# frame-relay interface-dlci

In the first three examples, a T-1 line is provided by the telco to both offices. Only in situation 3 and 4 does the company use frame-relay which requires that the telco has a frame-relay switch in the middle to switch frames to the proper destination circuit. Frame-Relay allows multiple systems to communicate over the same switched frame-relay cloud. PPP and HDLC are intended for only two systems to communicate. A T-1 might only have two ends, but multiple T-1 lines can come together within the telco company frame-relay switch and become a multipoint communication "cloud".

Anyone with three Cisco 2500 series routers and some serial cables could configure one to be a frame-relay switch and interconnect the other two routers. Whatever the limit is of the serial ports, that is the limit of your frame-relay speed. Last I checked, it was 2,000,000 mb/s... possibly 4,000,000 mb/s. A HSSI (high speed serial interface) can transmit much faster. If you had a T-1 connected to an external CSU/DSU, you would be able to use the lower speed 2500 series router serial port. If you had a T-3 connected to an external CSU/DSU, you would need the speed of an HSSI, a high-speed serial interface. It can be a card on a 3600 series, 7200 series, or many other routers.

=========== Scott Perry =========== Indianapolis, Indiana ________________________________________

P.S. The Lightstream 1010 was common for ATM in the LAN, also known as LANE and a nightmare to me.