📄 rfc3215.txt
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Ignore, it is an internal implementation error.
State: RESPONSE_AWAITED
Event: Internal Destroy
New State: IDLE
Actions:
Send an LDP-ABORT downstream, go to IDLE and delete the LSP
Control Block.
State: RESPONSE_AWAITED
Event: Internal Cross-Connect
New State: RESPONSE_AWAITED
Actions:
Ignore the event. It is an internal implementation error.
State: RESPONSE_AWAITED
Event: Internal New NH
New State: RESPONSE_AWAITED
Actions:
Send LDP-ABORT to the old downstream, and send LDP-REQUEST to the
new next hop.
2.2.5.3 State -- "ESTABLISHED"
State: ESTABLISHED
Event: LDP Request
Boscher, et al. Informational [Page 16]
RFC 3215 LDP State Machine January 2002
New State: ESTABLISHED
Actions:
Ignore the event. It's an internal implementation error. For non
VC-merge ATM LSR, a new LSP control block is always created for
each LDP request.
State: ESTABLISHED
Event: LDP Mapping
New State: ESTABLISHED
Actions:
Process the LDP-MAPPING, that may contain the new attributes of
the label mapping and then propagate the LDP-MAPPING upstream.
State: ESTABLISHED
Event: LDP Release
New State: IDLE
Actions:
Disconnect the upstream label from the downstream label.
Free the upstream label.
Free the resources.
Send event `Internal Destroy' to the Next Hop Trigger Control
Block if it was in the middle of switching over to the better next
hop.
Propagate the LDP-RELEASE downstream if the LSR is not the egress
for the LSP, go to IDLE and delete the LSP Control Block.
State: ESTABLISHED
Event: LDP Withdraw
New State: Depends on the action routine.
Boscher, et al. Informational [Page 17]
RFC 3215 LDP State Machine January 2002
Actions:
1) Free the resources and send LDP-RELEASE downstream.
2) If it is independent control mode, set the state to `IDLE',
create a internal LDP Request with the information in the LSP
Control Block, and pass event `LDP Request' to its own state
machine.
3) Else for the ordered control mode
3.1) If the LSP is triggered to be setup by itself (e.g it is
the ingress LSR of this LSP), send event `Internal LSP
Down' to the trigger control block, go to IDLE and delete
the LSP Control Block.
3.2) Else, if it is triggered by the incoming LDP Request,
Disconnect the upstream label from the downstream label.
Propagate the LDP-WITHDRAW upstream and go to state
`RELEASE_AWAITED'.
3.3) If the LSP is in the middle of switching over to a better
LSP, send event `Internal Destroy' to the state machine of
its New Next Hop LSP Control Block, go to IDLE and delete
the LSP Control Block.
State: ESTABLISHED
Event: LDP Upstream Abort
New State: ESTABLISHED
Actions:
Ignore the event.
Note: This scenario can occur if the upstream LSR sends a LDP-
ABORT at about the same time as the local LSR sends a LDP-MAPPING.
In this situation, it should be up to exactly one of the two LSRs
as to whether or not the label that was sent remains valid. The
LDP specification [4] procedures leave the choice to the upstream
LSR that must send an LDP-RELEASE if it will not use the label
provided.
State: ESTABLISHED
Event: LDP Downstream NAK
Boscher, et al. Informational [Page 18]
RFC 3215 LDP State Machine January 2002
New State: ESTABLISHED
Actions:
Ignore the event. It is a protocol error from the downstream LSR.
The downstream LSR should always LSP-WITHDRAW to tear down the LSP
when the LSP is established.
State: ESTABLISHED
Event: Upstream Lost
New State: IDLE
Actions:
Disconnect the upstream label from the downstream label.
Free the upstream label.
Send event `Internal Destroy' to the Next Hop Trigger Control
Block if it was in the middle of switching over to the better next
hop.
Free the resources.
Propagate an LDP-RELEASE downstream, go to IDLE and delete the LSP
Control Block.
State: ESTABLISHED
Event: Downstream Lost
New State: Depends on the action routine.
Actions:
1) If the LSP is triggered by the local router (Trigger Control
Block Pointer is not zero), send event `Internal LSP NAK' to
the Trigger control block, go to IDLE and delete the LSP
Control Block.
2) Else, disconnect the upstream label from the downstream label.
Propagate an LDP-WITHDRAW upstream and go to `RELEASE_AWAITED'
state.
Boscher, et al. Informational [Page 19]
RFC 3215 LDP State Machine January 2002
3) Send event `Internal Destroy' to the Next Hop Trigger Control
Block if it was in the middle of switching over to the better
next hop.
State: ESTABLISHED
Event: Internal Setup
New State: ESTABLISHED
Actions:
Ignore, it is an internal implementation error.
State: ESTABLISHED
Event: Internal Destroy
New State: IDLE
Actions:
Disconnect the upstream label from the downstream label if it is
not the ingress of the LSP.
Free the resources.
Send an LDP-RELEASE downstream, go to IDLE and delete the LSP
Control Block.
State: ESTABLISHED
Event: Internal Cross-Connect
New State: ESTABLISHED
Actions:
Connect the upstream label to the downstream label
May need to send a new LDP-MAPPING upstream with the attributes
from the new next hop.
Reset Trigger Control Block Pointer to zero.
State: ESTABLISHED
Event: Internal New NH
Boscher, et al. Informational [Page 20]
RFC 3215 LDP State Machine January 2002
New State: ESTABLISHED
Actions:
1) If the LSR was in the middle of switching over to a better next
hop (Next Hop Trigger Control Block Pointer is not zero), it
send `Internal New NH' to that control block.
2) Else, create a new Next Hop Trigger Control Block, set Next Hop
Trigger Control Block pointer to point to this control block,
and pass 'Internal New NH' to this control block.
2.2.5.4 State -- "RELEASE_AWAITED"
State: RELEASE_AWAITED
Event: LDP Request
New State: RELEASE_AWAITED
Actions:
Ignore the event. It is an internal implementation error.
State: RELEASE_AWAITED
Event: LDP Mapping
New State: RELEASE_AWAITED
Actions:
It is a protocol error from the downstream LDP peer, but anyway
send a LDP-RELEASE downstream.
State: RELEASE_AWAITED
Event: LDP Release
New State: IDLE
Actions:
1) Free the upstream label
2) Delete the control block.
State: RELEASE_AWAITED
Boscher, et al. Informational [Page 21]
RFC 3215 LDP State Machine January 2002
Event: LDP Withdraw
New State: RELEASE_AWAITED
Actions:
It is a protocol error from the downstream LDP peer, but send a
LDP- RELEASE anyway.
State: RELEASE_AWAITED
Event: LDP Upstream Abort
New State: IDLE
Actions:
1) Free the upstream label
2) Delete the control block.
State: RELEASE_AWAITED
Event: LDP Downstream NAK
New State: RELEASE_AWAITED
Actions:
Ignore the event. Continue waiting for the LDP-RELEASE from
upstream.
State: RELEASE_AWAITED
Event: Upstream Lost
New State: IDLE
Actions:
1) Free the upstream label
2) Delete the control block.
State: RELEASE_AWAITED
Event: Downstream Lost
Boscher, et al. Informational [Page 22]
RFC 3215 LDP State Machine January 2002
New State: RELEASE_AWAITED
Actions:
Ignore the event. Continue waiting for the LDP-RELEASE from
upstream.
State: RELEASE_AWAITED
Event: Internal SetUp
New State: RELEASE_AWAITED
Actions:
Ignore the event. It is an internal implementation error.
State: RELEASE_AWAITED
Event: Internal Destroy
New State: RELEASE_AWAITED
Actions:
Ignore the event. It is an internal implementation error.
State: RELEASE_AWAITED
Event: Internal Cross-Connect
New State: RELEASE_AWAITED
Actions:
Ignore the event. It is an internal implementation error.
2.2.6 Handling the Next Hop Change
When an LSR detects a better next hop, it may decides to establish a
new LSP through this next hop. For example, an LSR is configured as
"local repair", or the LSR is configured as "global repair" and it is
the ingress end of a LSP. It can then create a Next Hop Trigger
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