Information Technology Reference
In-Depth Information
Table8-12 Novell IPX: Intermittent Connectivity (continued)
Possible Problem
Solution
SAP updates are dropped
from the hub router's output
queue.
Slow serial lines can cause the router to drop SAP
packets before they are transmitted.
Use the
show interfaces serial
exec command,
and examine the output queue drops field. A large
number of dropped packets might indicate that
SAP updates are being dropped before they can be
transmitted across the serial link.
1.
Use the
show ipx servers
exec command on the
router. Compare the output of this command with
the output of the
display servers
system console
command on Novell servers.
2.
If the
display servers
output for a Novell server
shows only a partial listing of the SAP entries
shown by the router, the router might be dropping
SAP packets from the output queue.
3.
Eliminate the forwarding of any SAP updates that
are not absolutely necessary. Configure filters
using the
ipx input-sap-filter
,
ipx
output-sap-filter
, and
ipx router-sap-filter
interface configuration commands, as appropriate.
4.
Increasing the output hold queue on the serial
interface might also improve performance. Use
the
hold-queue
length
out
interface configuration
command to increase the output
hold queue
length
. The default output
hold-queue
limit is 100
packets. The general rule when using the
hold-queue
command is to use a small output
hold-queue
limit for slow links. This approach
prevents storing packets at a rate that exceeds the
transmission capability of the link. For fast links,
use a large output
hold-queue
limit. A fast link
may be busy for a short time (and thus require the
hold queue), but it can empty the output hold
queue quickly when capacity returns.
5.
If SAP filters and increased queue lengths do not
solve the problem, increase the available
bandwidth, if possible. Add a second serial line,
or obtain a single link with more available
bandwidth.
1
6.