Configuring Rate Limiting; Setting The Committed Burst Rate - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Setting Up Quality of Service
Configuring Rate Limiting for Frame Relay
7-52

Configuring Rate Limiting

By default, Frame Relay interfaces always forward packets at their transmis-
sion rate. However, because Frame Relay networks operate over shared lines,
the network may sometimes be congested and unable to forward all the traffic
the router sends it. Rate limiting prevents the router from forwarding packets
only to have those packets dropped.
Rate limiting can also help maintain QoS between two peers that have a
different amount of bandwidth. For example, the local router may have an
MLFR connection over 2 E1 lines, providing 4 Mbps, while the router at the
remote site only has 2 Mbps available for the connection. It is pointless for the
local router to send 4 Mbps of data only to have the remote router drop the
packets it cannot receive.
You shape Frame Relay traffic by setting the committed burst value (B
the excessive burst value (B
the Frame Relay subinterface can use when the line is and is not congested.
The total burst values for all PVCs on an interface should be less than the
interface's access rate to save bandwidth for overhead bits the router does not
count when calculating transmission rates. If you set the burst rates too high,
the connection will become oversubscribed and queues will build. The access
rate is the physical rate limit; manually limiting traffic to this rate is unneces-
sary and defeats the purpose of traffic shaping.

Setting the Committed Burst Rate

Your service level agreement (SLA) with your Frame Relay provider specifies
the bandwidth that the provider guarantees each PVC, or the PVC's committed
information rate (CIR). The CIR is calculated from the B
maximum number of bits that the service provider guarantees to forward
during a certain interval of time (T). The CIR is B
You should set a B for each Frame Relay subinterface to ensure that the PVC
c
does not exceed its CIR. Some service providers penalize you for consistently
transmitting more than the agreed-upon amount of traffic.
You configure the value in bits. Because the Secure Router OS, like most
service providers, always considers the time interval to be one second, the B
is effectively the CIR. To set the B
Relay subinterface configuration mode context:
Syntax: frame-relay bc <bits>
).These values determine how much bandwidth
e
c
, enter the following command from a Frame
c
c)
, which is the
c
/T.
and
c