Subject: [forces] comments #7

From: Jamal Hadi Salim <[email-masked]>
Date: Fri, 12 Aug 2011 05:24:01 -0400

Authors - please ACK my emails so i know i should send more.
Continuation of comments:

0) Please check doc for consistency. At times you refer to this
LFB as EtherEncapsulator - it should really be EtherEncap.

i) "This LFB abstracts the process to encapsulate IP packets to Ethernet
packets according to the L2 information"
to:
"This LFB abstracts the process of encapsulating ethernet headers
onto received packets. The encapsulation is based on passed metadata."

ii) "The LFB is expected to receive types of IP packets, including IPv4
and IPv6 types"
to:
"The LFB is expected to receive IPv4 and IPv6 packets"

iii) "Optinally an input packet may be accompanied by a Vlan priority
metadata. In this case, default value for the metadata is 0."
to:
"In the case an input packet contains only a Vlan priority field metadata,
a default vlan tag of 0 is assumed"
Question: Dont we already have a Vlan tag of 0 by the time the packet
is passed here? Also, where does this priority vlan field gets set?
I dont recall seeing it being produced at any LFB earlier.

iv)This is one of those general comments I made that we dont say what
the lookup keys are etc:
"Upon a successful table lookup,"
to:
"The EncapTable is looked up using the MediaEncapInfoIndex.
Upon a successful table lookup, ..."

v) Referring to the above - how do i know by looking at the XML
that MediaEncapInfoIndex is the index used for the encaptable?
Should there be at minimal some synopsis description somewhere that
tells me this?

vi) It makes sense to say what the ExceptionID that is passed is
downstream is known as - I am a little confused as to what the text
is referring to.

vii) This text was very confusing:
"The upstream LFB may be programmed by the CE to pass along a
MediaEncapInfoIndex that does not exist in the EncapTable. That is
to allow for resolution of the L2 headers, if needed, to be made at
the L2 encapsulation level in this case(ethernet) via ARP, or ND (or
other methods depending on the link layer technology) when a table
miss occurs."

change to:

"In case of a table miss, i.e.  the MediaEncapInfoIndex does not exist
in the EncapTable, an exception is generated to be used by the
downstream LFBs. This exception could allow for resolution of the L2
headers, if needed, to be made at a downstream LFB via ARP, or ND (or
other methods depending on the link layer technology). Refer to section
blah blah which describes the different techniques ARP could be implemented."

And for that reason, please remove the next paragraph and integrate it
into section 7 - where you should talk about both the CE and inline
ways (as described above) to do ARP/ND.

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more comments after i get ACKs to these two emails.

cheers,
jamal