NS3000/iX Error Messages Reference Manual (36923-90041)

414 Chapter19
Logging Location Codes
ICMP Type/Code Words
MESSAGE: Source Quench.
400 CAUSE: Several things can trigger source quench messages: (1) A
gateway, intermediate router node or destination node was unable to
forward or deliver the IP datagram because of lack of resources (e.g.,
buffers). (2) A gateway, intermediate router node or destination node
was unable to forward or deliver the IP datagram because the capacity
limit of resource (e.g., buffers) is being approached. In this case, the IP
datagram is NOT discarded. On receipt of a source quench ICMP
message, the source will cut back its rate of TCP traffic to the
destination node specified in the ICMP message. Source quench
messages are sent to the source of the traffic and therefore logged at the
source. The source node will gradually increase the rate at which it
sends traffic to the destination.
ACTION: Reception of this ICMP message can occur in normal network
operation, but if this problem persists, it may be necessary to review
the resource allocation at the node generating the ICMP message. It
may require increasing the number of store and forward buffers
configured in the IP Protocol screen or the number of inbound buffers
configured in the appropriate network interface screen. Care should be
taken in increasing these values since this increases the queuing at
these nodes and may result in longer delays. It is recommended that
you review the traffic patterns and perhaps alter the routing
information so that a better path is chosen
MESSAGE: Redirect.
500 CAUSE: A gateway has received an IP datagram that originated from
the node (local node) that logs this message. It indicates that the local
node's routing information is incorrect or out-of-date. The Redirect
message will cause the local node to send its traffic for the destination
network to the gateway specified in the Redirect message.
ACTION: Reception of this ICMP message can occur in normal network
operation. Depending on the cause of the Redirect message different
actions should be taken. If the networks are operating on the gateway
that sent the Redirect then the local node's routing information
conflicts with the gateway's routing information. The conflict occurs
when the local node thinks that the gateway sending the Redirect (G1)
is the best path to a given network (N1), whereas G1 thinks that
another gateway (G2) is best. The Redirect will dynamically alter the
routing information in the local node so that traffic for N1 will be sent
to G2 instead of G1. This new routing information will be lost when the
local node's network transport is shut. In this case reconfigure either
the local node or gateway so the routing information to N1 is consistent.
The Redirect may also be caused by a link failure or a network that is
not operational on the gateway (G1) that sent the Redirect. In this case,
it is possible that G1 may, depending on the topology, misroute packets