Dale
The Frame-Relay service does not use ICMP, this would come from the end
node. The FECN/BECN would tell the edge switch, or router (depending on your
service providers implementation of Frame-Relay), to throttle back, and if
you are implementing certain features of Cisco's IOS (Adaptive Shaping) this
could go all the way back to the router, and could be used to modify the
traffic output of the router, upon its learning of congestion. The fact that
a switch in the core network is sending back FECNs, or BECNs is mostly used
to set DE in the core. This is assuming that the core is based on Cisco IGX,
BPX, Switches. Cisco base Core ATM network can use Cisco's Foresight
congestion. Following is taken from CCO:
ForeSight is an advanced traffic management feature that reacts quickly to
the slightest hint of congestion. On Frame Relay backbones, ForeSight
detects congestion on a trunk, egress port, or virtual circuit and adjusts
admission rates in the network at the point of ingress for a virtual
circuit. Using CLLM, ForeSight can be extended to the router. Cisco calls
this router feature Router ForeSight.
Hope it helps,
EF (77 days until CCIE LAB)
-----Original Message-----
From: Dale Cantrell [mailto:[EMAIL PROTECTED]]
Sent: Monday, June 12, 2000 10:26 PM
To: [EMAIL PROTECTED]
Subject: What came first?
Evening all,
I'm reading about Frame Relay on Protocols.com and a question arises.
When the network becomes congested to the point that it cannot process
new data transmissions, it begins to start discarding frames. Two bits are
changed in the F.R. header..FECN bit and BECN bit. In this way all
downstream nodes and the attached user device learn about congestion on the
line.
Does this not mean that ICMP would send a "buffer full" message, and
I thought that was the job of a "source-quench message"? Any movement of the
definition lines would be gladly received.
Ya'lls truly, :>)
Dale
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