Alcatel Omni Switch/Router, User Manual

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Configuring SPX Keepalive Spoofing
Page 27-30
Configuring SPX Keepalive Spoofing
The
spxspoof
command is used to enable and disable SPX Keepalive Spoofing on any or all
WAN routing services. The use of this feature is explained below:
Novell’s SPX Keepalive Protocol, which is used by NetWare to maintain SPX connections
between end nodes, can also consume significant network bandwidth and thereby incur
unnecessary costs on expensive dial-on-demand, pay-per-packet WAN links. The Omni
Switch/Router provides a SPX Keepalive Spoofing feature to prevent keepalive packets from
keeping WAN links active when they are not otherwise needed for data transmissions.
The SPX Spoofing feature enables the switch to respond to client/server keepalive packets on
the behalf of the remote clients/servers. SPX spoofing thereby effectively stops keepalive
packets from crossing a WAN link while maintaining existing SPX connections.
SPX-Packet Tolerance Counting
NetWare’s SPX and SPXII watchdog and keepalive packets unfortunately are not labeled with
a unique packet type. Therefore, valid acknowledge packets or window-update packets could
be mistaken for keepalive packets. To prevent blocking of critical packets, a packet tolerance
counting mechanism is employed by the Spoofing feature to count SPX packets.
When active, the Spoofing feature observes all watchdog and keepalive packets as they go
between network endpoints. If successive packets are found to have the same sequence
number, acknowledge number, and “alloc” number, spoofing will not begin until the speci-
fied SPX-packet tolerance count has been reached. Only watchdog packets which have the
ACK_REQUSTED
bit set will have an effect on the SPX-packet tolerance counter.
Once the specified tolerance count has been reached, spoofing of watchdog packets will
begin and all keepalive packets will be dropped. Refer to
Controlling IPX Type 20 Packet
Forwarding on page 27-32 for help on using NetWare’s configurable parameters to change
the frequency and number of keepalive/watchdog packets sent.
Enabling SPX Keepalive Spoofing
Follow the steps below to enable SPX Keepalive Spoofing.
1. Enter
spxspoof
.
A screen similar to the following displays:
View the current spoofing status of all WAN routing services? (y or n) (n) :
Enter
y
if you do want to see the current SPX spoofing status. Enter
n
(or press
<Enter>
) if
you entered this command by mistake or if you don’t need to see the current status.
2. A screen similar to the following displays:
Group SPX Spoofing
----------
----------------------------
3 Disabled
4 Disabled
Enter Group (default: all WAN) :
Enter a Group number to proceed to enable SPX spoofing for that particular Group.
Or, press
<Enter>
to proceed to enable SPX spoofing for all WAN routing services.
3. The following prompt displays:
Enable Spoofing? (y or n) (n) :