Bridging Service
Token Ring Solutions
DEC Terminal Server
ROUTER
ROUTER
Figure 9. Tunneling Used to Connect DEC VAXes Through a Token Ring Backbone
Tunneling is a feature of the bridgingservice. It is not specifically enabled or
configured. Instead, when the bridging software recognizes that an Ethernet
packet is being transmitted onto a token ring network, the bridged packet is
encapsulated for transmission to another HP router. Thus, tunneling requires
one HP router to encapsulate the packet and another HP router to de-encap-
sulate the packet. Figure 10 shows the encapsulation performed on Ethernet
packets to be transmitted over token ring backbones and on token ring
packets to be transmitted over Ethernet backbones.
2-17