Subject: Clarifications regarding G-ACH and GAL

From: "Jishnu A" <[email-masked]>
Date: Wed, 21 Jan 2009 18:57:21 +0530

Dear Martin,

This mail is in reference to the
http://tools.ietf.org/html/draft-ietf-mpls-tp-gach-gal-01 draft. I have the
following queries:

-        Suppose I am using GAL for sending the control/management
information and using say Label 30 all along the LSP to send my data plane
information from A <-> Z. Assuming a MIP in between say node B, with the
MPLS label swap table indicating that
<ingresslabel=30,egressport=p1,egresslabel=30> and the G-ACH channel is
denoted in B as <ingresslabel=GAL,egressport=p1,egresslabel=GAL>. Now due to
some configuration error an operator modified the label swap table at B as
<ingresslabel=30,egressport=p1,egresslabel=20> and did not make any error
with G-ACH channel (<ingresslabel=GAL,egressport=p1,egresslabel=GAL>)
remained same. So now the control and management plane are working properly
but actual data plane is down. How does this draft address this?

-        Suppose there are 6 nodes in an LSP A<->B<->C<->D<->E<->Z. Suppose
there are two MD one between C and D (MD#1) and another between B and E
(MD#2). Does the MEP at B generate a G-ACH with GAL which reaches node C
which is a MIP and it then forwards it but then C is also a MEP in MD#2
which again generates a G-ACH with GAL value. How does D differentiate
between the MD#1 and MD#2 G-ACH messages?

-        How do you ensure G-ACH channels are bidirectional and hops along
the same path?

-        When control plane is down, why should the management plane also
get affected (as per present draft control and management are piggybacked
within one GAL)?

Regards,

Jishnu A