3Com PathBuilder S200 Series Owner's Manual page 108

LLC2 Local Termination
Spoofing
Maximum Sessions
Spoofed
What Happens
between Spoofers
Intermediate
Frames between
Spoofers
FEP
#1
104
Local termination or "spoofing" of LLC protocol means that acknowledgments to
information frames and certain supervisory frames are handled locally by the
spoofer. The spoofer, the LT software in a PathBuilder S200 series switch, ensures
the acknowledged information frames are reliably delivered to the destination peer
spoofer and that any flow control issues are handled appropriately. Because of local
acknowledgment, spoofing of LLC frames may enhance network performance and
allows for reliable Token Ring to Token Ring connectivity.
This table describes the types of frames Local Termination spoofs:
All Specifically Routed LLC frames, such as I frames and Supervisory frames
Local Termination does not spoof:
• Route Explorer frames, such as ARE or STE
• Internally matched frames coming in from the LAN port
• Frames generated by LSS/LLC in the bridge going out to the LAN port
• WAN to WAN frames
The maximum number of sessions you can spoof at one time is 64. If you reach the
maximum number of sessions, Local Termination does not establish additional
spoofing sessions, nor does it source route bridge the additional sessions.
Local Termination runs a subset of LLC2 protocol between spoofers to ensure that
frame traffic reliably passes from one edge point node to another edge point node in
your network. The subset protocol uses separate timers and retry counts that can be
set greater than the LLC protocol timers.
LLC2 LT supports intermediate Token Ring networks between spoofers. For
example, Figure 53 shows Local Termination running in the edge point nodes of this
network to provide "spoofing" across multiple Token Rings.
X.25
PB
LT
LT enabled with MAC
Address of FEP #1 and
SAP value being used.
Figure 53. Example of LT Spoofing
Local Termination spoofs:
Spoofing
Intermediate Ring
PB PB
BN BN
LT enabled with MAC
Address of FEP #2 and
SAP value being used.
FEP End
PB
Station
#2
LT
Bridging