Frame Relay top speed 1.54 Mbps?

Have a question or want to start a discussion? Post it! No Registration Necessary.  Now with pictures!

Threaded View
Im just starting to learn CCNA, go easy on me :)

I keep seeing text stating that "Frame Relay can provide data transfer
rates of up to 1.54 Mbps". Then in the next paragraph it will say:
"Frame Relay can be implemented over a variety of connection lines
including 56K, T1, T3"

My  questions: Why would you be running frame relay on a T3 (45Mbps)
if its data transfer speed is limited to 1.544Mbps? Is that really the
top speed for frame relay? 1Would companies typically have multiple
Frame Relay connections? All running on a seperate physical lines? or
through a single T3 perhaps?   Im confused!

Any basic/brief info would be appreciated


Re: Frame Relay top speed is 622 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.


Re: Frame Relay top speed 1.54 Mbps?
Quoted text here. Click to load it
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....

Quoted text here. Click to load it
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.

Quoted text here. Click to load it
--
Regards

stephen_hope@xyzworld.com - replace xyz with ntl



Re: Frame Relay top speed 1.54 Mbps?
Quoted text here. Click to load it

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


Re: Frame Relay top speed 1.54 Mbps?
Quoted text here. Click to load it
starting to learn CCNA, go easy on me :)
Quoted text here. Click to load it
telcos -
Quoted text here. Click to load it
speed
E3

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...
Quoted text here. Click to load it
--
Regards

stephen_hope@xyzworld.com - replace xyz with ntl



Re: Frame Relay top speed 1.54 Mbps?
Quoted text here. Click to load it

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


Re: Frame Relay top speed 1.54 Mbps?
Quoted text here. Click to load it
just
transfer
F/R is
Quoted text here. Click to load it
(45Mbps)
Quoted text here. Click to load it
the
multiple
or
telco
encapsulation
high
such as
case
sub

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 -
2.4G trunks between the 7670s.....
Quoted text here. Click to load it
--
Regards

stephen_hope@xyzworld.com - replace xyz with ntl



Re: Frame Relay top speed 1.54 Mbps?
Quoted text here. Click to load it

Thats fast! Thanks for the information-much appreciated.


Re: Frame Relay top speed 1.54 Mbps?


ANSWER: The technology of Frame-Relay is not limited to the speed of a =
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:
    =20
     Situation #1 - PPP
          A single T-1 line is run directly between two office =
locations.
         =20
          RouterA(config)# interface serial 0
          RouterA(config-if)# encapsulation ppp
          RouterA(config-if)# ip address <ip address/subnet mask>
    =20
          RouterB(config)# interface serial 0
          RouterB(config-if)# encapsulation ppp
          RouterB(config-if)# ip address <ip address/subnet mask>
    =20
     Situation #2 - HDLC
          A single T-1 line is run directly between two office =
locations.
         =20
          RouterA(config)# interface serial 0
          RouterA(config-if)# encapsulation hdlc
          RouterB(config-if)# ip address <ip address/subnet mask>
    =20
          RouterB(config)# interface serial 0
          RouterB(config-if)# encapsulation hdlc
          RouterB(config-if)# ip address <ip address/subnet mask>
    =20
     Situation #3 - Frame-Relay
          Two T-1 lines are run between two office locations with the =
telco providing a frame-relay switch in between.
         =20
          RouterA(config)# interface serial 0
          RouterA(config-if)# encapsulation frame-relay
          RouterA(config)# interface serial 0.1
          RouterA(config-if)# ip address <ip address/subnet mask>
          RouterA(config-if)# frame-relay interface-dlci <DLCI number>
    =20
          RouterB(config)# interface serial 0
          RouterB(config-if)# encapsulation frame-relay
          RouterB(config)# interface serial 0.1
          RouterB(config-if)# ip address <ip address/subnet mask>
          RouterB(config-if)# frame-relay interface-dlci <DLCI number>

    Situation #4 - Frame-Relay
          Three T-1 line are run between three office locations with the =
telco providing a frame-relay switch in between.
         =20
          RouterA(config)# interface serial 0
          RouterA(config-if)# encapsulation frame-relay
          RouterA(config)# interface serial 0.<sub-interface number>
          RouterA(config-if)# ip address <ip address/subnet mask>
          RouterA(config-if)# frame-relay interface-dlci <DLCI number>
    =20
          RouterB(config)# interface serial 0
          RouterB(config-if)# encapsulation frame-relay
          RouterB(config)# interface serial 0.<sub-interface number>
          RouterB(config-if)# ip address <ip address/subnet mask>
          RouterB(config-if)# frame-relay interface-dlci <DLCI number>
    =20
          RouterC(config)# interface serial 0
          RouterC(config-if)# encapsulation frame-relay
          RouterC(config)# interface serial 0.<sub-interface number>
          RouterC(config-if)# ip address <ip address/subnet mask>
          RouterC(config-if)# frame-relay interface-dlci <DLCI number>

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. =20
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. =20
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.

     =3D=3D=3D=3D=3D=3D
     Scott Perry
     =3D=3D=3D=3D=3D=3D
Indianapolis, Indiana
________________________________________

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

Quoted text here. Click to load it



Site Timeline