enables output describing every SAP update sent and received. Notice the update Yosemite
wants to send out network 1023; it is time to send a SAP broadcast, but the SAP update is null.
This is because the only SAP in the table (Server1, SAP type 4) was learned from Seville over
network 1023, so Yosemite is using split horizon rules to not send information about this SAP
back to Seville.
to the beginning of Example 6-20, notice that the route to network 1013, metric [7/1],
points to next hop 1023.0200.cccc.cccc (Seville), out Yosemite's Serial 1 interface. However,
1012.0200.aaaa.aaaa (Albuquerque) is sending RIP updates describing a route to network 1013,
with seven ticks and one hop into Yosemite's S0 interface (see RIP debug output). Yosemite
heard from Seville first; therefore, only that route is included. If the ipx maximum-paths 2
global command had been configured on Yosemite, both routes would be included. Unlike with
IP, when two routes are in the IPX routing table, per-packet load balancing across these paths
occurs, even if fast switching is enabled.
are in the routing table may not be desired because packets can arrive out of order. By having
the router send all packets to an individual IPX address over the same route every time, those
packets should be received in order. The ipx per-host-load-share configuration command
disables per-packet balancing and enables balancing based on the destination address. Of
course, the penalty is that the traffic will not be completely balanced, based on the numbers of
packets to each destination.
protocol (typically IP) for transport across a network to another router. The receiving router
de-encapsulates the packet, leaving the original protocol. Each intermediate router that is used
between the endpoints of the tunnel is unaware of the protocol being encapsulated. Figure 6-16
shows the basic process and the physical and logical view of an example network.
IPX being encapsulated. The incoming Ethernet frame on the left of the figure is processed as
normal, up to a point--the Ethernet header is discarded, and a routing decision is made to
forward the packet out the tunnel interface. A tunnel interface is created on Router A and Router
D to represent the function of tunneling. When the routing logic directs the packet out the tunnel
interface, the encapsulation logic described in Figure 6-16 takes over, resulting in an IP packet.