Alcatel Carrier Internetworking Solutions Omni Switch/Router - Manual (Page 806)

Configuring IPX RIP/SAP Filtering
Page 27-18
Configuring IPX RIP/SAP Filtering
The ipxfilter command is used to add or delete an IPX RIP or SAP Output or Input filter. The
IPX RIP/SAP Filtering feature give you a means of controlling the operation of the IPX RIP/
SAP protocols. By using IPX RIP/SAP filters, you can minimize the number of entries put in
the IPX RIP Routing and SAP Bindery Tables, improve overall network performance by elimi-
nating unnecessary traffic, and control users’ access to NetWare services.
Five types of IPX RIP/SAP filters are available:
1. RIP Input filters control which networks are allowed into the routing table when IPX RIPs
are received.
2. RIP Output filters control the list of networks included in routing updates sent out an inter-
face. These filters control which networks the router advertises in its IPX RIP updates.
3. SAP Input filters control the SAPs received by the router prior to a router accepting infor-
mation about a service. The router will filter all incoming service advertisements received
before accepting information about a service.
4. SAP Output filters control which services are included in SAP updates sent by the router.
The router applies the SAP output filters prior to sending SAP packets.
5. GNS Output filters control which servers are included in the GNS responses sent by the
router.
Here are some example uses of IPX RIP/SAP filters:
• RIP Input and Output filters can be used to isolate entire network segments (and/or rout-
ers) in order to make the network appear differently to the different segments.
• RIP Input and Output filters can be used to reduce the amount of WAN traffic needed to
advertise routes that shouldn't be used by a particular network segment.
• SAP Input and Output filters can be used to improve the performance of IPX in a WAN
environment by limiting the amount of SAP traffic. For example, because printing is gener-
ally a local operation, there’s no need to advertise print servers to remote networks. A SAP
filter can be used in this case to restrict “Print Server Advertisement” SAPs.
♦ Important Note ♦
All types of IPX Filters can be configured either to
allow or to block traffic. The default setting for all filters
is to allow traffic. Therefore, you will typically only
have to define a filter to block traffic. However, defin-
ing a filter to allow certain traffic may be useful in situ-
ations where a more generic filter has been defined to
block the majority of the traffic. For example, you
could use a filter to allow traffic from a specific host on
a network where all other traffic has been blocked. A
discussion of the precedence of “Allow” filters appears
later in this section. Keep in mind that precedence
applies only to “allow” filters, not to “block” filters.
You can apply filters to all router interfaces by defining a “global” filter, or you can limit the
filter to specific interfaces. In addition, for WAN networks, you can apply filters to a specific
Frame Relay virtual circuit (DLCI) or PPP Peer. Each of these options is described under indi-
vidual heading in this section.