- Scenario:
- We want to
re-locate (move)
a node (e.g.: C) from
one Ethernet segment to
another Ethernet segment:
Example:
Result:
- Before moving
node C:
- After moving
node C:
- Consequence:
- Node C can not receive messages from some nodes
Example: if node A transmits a frame to node C
- We want to
re-locate (move)
a node (e.g.: C) from
one Ethernet segment to
another Ethernet segment:
- The cause of the
relocation problem:
- The entry for
node C is:
- still associated with the old port
I.e.:
- The entry for node C is in the wrong forwarding table !!!
- The entry for
node C is:
- Solution: use
time out to
remove
inactive entries !!!
- Entries in the
forwarding table in
Transparent bridging
has a
expiration time:
- Timer refresh:
- When the bridge
receives
a transmission,
from source ID,
the bridge
must reset
the expiration timer
(= "renewal")
- When the bridge
receives
a transmission,
from source ID,
the bridge
must reset
the expiration timer
(= "renewal")
- Expiration:
- If a node
has not
transmitted for
a long time on
a segment:
The timer will expire !!!
- The expired entry will be
removed:
- If a node
has not
transmitted for
a long time on
a segment:
- Entries in the
forwarding table in
Transparent bridging
has a
expiration time:
- Result:
- The bridge will
now
forward
frame destined for
node C:
- When node C
replies,
the bridge will
learn
the location of
C:
- The bridge will
now
forward
frame destined for
node C: