
Configuring Bridging Services
1-4
117351-A Rev. A
Figure 1-2. RFC 1042 Encapsulation
AppleTalk Address Resolution Protocol (ARP) frames (Ethernet frames with a
protocol type equal to 80F3) require special translation by the Bridge Tunnel
Service.
Figure 1-3 illustrates the LLC and SNAP headers of the AppleTalk ARP outbound
frame after the Bridge Tunnel Service translation.
Figure 1-3. Bridge Tunnel Service Encapsulation
The bridge translates all IEEE 802.2 LLC frames by removing the length field.
Protocols in this category include AppleTalk Phase 2, Novell Proprietary, and IP.
Figures 1-4 and 1-6 illustrate different LAN configurations and show how bridge
A translates different types of frames originating on LAN 1 for transmission
across the FDDI LAN. Figure 1-5 shows how bridge B translates frames
transmitted from the FDDI LAN to LAN 2.
SNAP LLC
DSAP SSAP Control OUI Protocol type
0 xAA 0 xAA 03 000000 (original type)
BRG0002A
SNAP LLC
DSAP SSAP Control OUI Protocol type
0 xAA 0 xAA 03 0000F8 80F3
BRG0027A
Key
SNAP = Subnetwork Access Protocol
LLC = Logical Link Control
DSAP = Destination service access point
SSAP = Session service access point
OUI = Organizationally unique identifier
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