This blog was originally started to better help me understand the technologies in the CCIE R&S blueprint; after completing the R&S track I have decided to transition the blog into a technology blog.

CCIE #29033

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Sunday, April 25, 2010

Question 19

Whats is FRTS and what does it help with?

1 comments:

Packets Analyzed said...

FRTS - Frame-relay Traffic Shaping is used to control the amount of data sent from a router to a specific DLCI or interface.

Shaping delays excess traffic where policing drops traffic.

AR - Available Rate, Physical speed of an interface that is provided by the clock rate.
CIR - Committed Information Rate, Is the rate at which the router will send at. When using FRTS the default is 56kbps.
MINCIR - Minimum CIR, The frame relay service provider guaranteed minimum rate. DE bits may be set on any traffic that is above the MINCIR. MINCIR is half the configured CIR by default.
Bc - Committed Burst, Committed bits allowed to be sent per interval. Speeds below ~650kpbs is 1/8 and speeds above the time interval is 1/16.
Be - Excess Burst, The amount of non-committed data send above Bc with the first time interval (Tc). No default
Tc - Committed Rate Measurement Interval, Time interval that Bc or Bc + Be can transmit data. Maximum time interval is 125ms (1/8 of a second) and Minimum is 10ms (1/100 of a second)

Frame-relay shaping is set on the interface (the default FOR DLCI's is 56kbps without map classes)

Global Config
-"map class frame-relay (name)"
-"frame-relay cir (bps)" defines the CIR for the map-class
-"frame-relay mincir (bps)" Sets the MINCIR for the map-class. Remember this is the lowest rate the router will throttle to during congestion
-"frame-relay bc (bps)" this sets the committed burst. Tc = Bc/CIR
-"frame-relay be (bits)" This sets the excessive burst size for the map-class
-"frame-relay adaptive-shaping (becn|foresight|inter-congestion (queue-depth)" Allows a router to throttle back when there is congestion. When a router receives a BECN it throttle back 25% per time interval (Tc). (This continues for each BECN until the MINCIR is met)
map-class command. The interface-congestion option allows the router to throttle down past the MINCIR.
"frame-relay fecn-adapt" enables the router to relay a BECN to the source asking the source to slow down.

Interface Config
"frame-relay class (name)" applies the map-class the interface or sub interface.

DLCI config
"class (name)" Applied to the DLCI and overrides interface map class

"show traffic-shape (interface)" shows traffic shaping settings
"show traffic-shape ?"

Math (I will not go through this in this post but I may create a question to show how it works)
Bc=CIR*Tc
CIR=Bc/TC
TC=Bc/CIR

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