Hello?
Anyone got an answer?
Thanks,
Adrian
----- Original Message -----
From: "Adrian Farrel" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, August 25, 2007 1:56 AM
Subject: [Pce] Question about PCEP Keepalive
Hi,
I'm looking at r08 sections 6.3 and 7.2.
Section 6.3 has
Note that sending Keepalive messages to maintain the session alive is
optional and PCEP peers may decide to not send Keepalive messages
once the PCEP session is established.
Section 7.2 has
Keepalive (8 bits): maximum period of time (in seconds) between the
sending of PCEP messages. The minimum value for the Keepalive is 1
second. When set to 0, once the session is established, no further
Keepalive messages need to be sent to the remote peer.
And also
A sends an Open message to B with Keepalive=10 seconds and
Deadtimer=30 seconds. This means that A sends Keepalive messages (or
ay other PCEP message) to B every 30 seconds and B can declare the
PCEP session with A down if no PCEP has been received from A.
I find this peculiar. Sending a keepalive message does not verify for the
sender that the session is open. It verifies for the receiver. So, surely
the parameter in the Open object says how frequently the sender of the
Open
message wants to receive a Keepalive message. That is, how often the
receiver of the Open message must send a Keepalive message.
For example, if a PCC is worried that the session may fail, it will want
to
operate the keepalive process. But as currently specified, the PCC can
only
tell the PCE how often the PCC will send Keepalive messages, and after
what
period the PCE may declare the session dead. This is no help to the PCC!
If
the PCE decides that it will not send Keepalive messages then the PCC
cannot
determine the health of the session and cannot switch to a new PCE.
In other words, the keepalive process is back-to-front.
Further, I don't see why you need the keepalive timer value and the dead
timer value. One value can be derived from the other, probably through a
recommended ratio of 3.5.
Lastly, when describing that the use of keepalive is optional, there are a
couple of points:
1. Optional should be an RFC 2119 word
2. You need to make it clear that it is not the "PCEP peers"
that decide to not send keepalives, but "each PCEP peer"
that decides "whether it wants to receive keepalives"
3. You should indicate the circumstances surrounding
the choice for this option. I think that, you might suggest
that if PCE discovery is in use, the failure of a PCE can
be speedily detected by the failure of the IGP, and can
be flooded by timing out the LSA containing the discovery
information. In this case, keepalive would not be needed.
Yes?
Adrian
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