Subject: [PWE3] draft-ietf-pwe3-pw-mib-10 - fcsRetentionFcsStatus

From: "Ben Wright" <[email-masked]>
Date: Fri, 13 Apr 2007 16:38:24 +0100

Hi David, 

I have a query about th fcsRetentionFcsSizeMismatch bit in the fcsRetentionFcsStatus field.  The description says is "Set if there is an FCS size mismatch between the local and the peer node."

By RFC 4623, each node signals an interface parameter indicating whether they support fragmentation.  However, this parameter doesn't contain the configured FCS size.  Given this, how does a PE router learn that there has been an FCS size mismatch?   

Cheers, 

Ben 

Ben Wright
Network Protocols Division
Data Connection Ltd (DCL)
Tel:    +44 20 8366 1177          Fax:  +44 20 8363 1039
Email: mailto:[email-masked]
Web:   http://www.dataconnection.com

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From: "David Zelig" <[email-masked]>
Date: Sun, 15 Apr 2007 15:47:40 +0300

Ben,
PWE3 Fragmentation is defined in RFC 4720 (not 4623), and there is error
(or more precisely status in LDP signaling and error in L2TPv3
signaling) if the size is not compatible between peers. I assumed that
the actual size is not part of the pw set of MIBs since the FCS size is
known to the agent from the interface configuration.

However in the fragmentation text in PW TC MIB I see some error in
PwFragStatus reference to FCS size configuration (this has confused you
with RFC 4623?). For fragmentation size configuration there are
differences between LDP and L2TPv3 signaling that should be captured in
the text.

I will fix both texts in the following versions.

Thanks
David

-----Original Message-----
From: Ben Wright [mailto:[email-masked]] 
Sent: Friday, April 13, 2007 6:38 PM
To: David Zelig
Cc: Cisco - Thomas Nadeau; [email-masked]
Subject: draft-ietf-pwe3-pw-mib-10 - fcsRetentionFcsStatus

Hi David, 

I have a query about th fcsRetentionFcsSizeMismatch bit in the
fcsRetentionFcsStatus field.  The description says is "Set if there is
an FCS size mismatch between the local and the peer node."

By RFC 4623, each node signals an interface parameter indicating whether
they support fragmentation.  However, this parameter doesn't contain the
configured FCS size.  Given this, how does a PE router learn that there
has been an FCS size mismatch?   

Cheers, 

Ben 

Ben Wright