On Dec 13, 2012, at 12:38 PM, Stewart Bryant wrote:

> The draft as it stands is not MPLS specific and thus I am not convinced
> we should add the information you propose to this draft, although
> perhaps some text could go in a new section. However if we include
> this text, we need to consider what we should say about IP tunnels.

rfc5286 is not MPLS specific either, yet the majority (>90%) of my customers
see it as lightweight alternative to get local-repair protection for their LDP 
networks.
draft-ietf-rtgwg-remote-lfa-00 is not LDP specific either, however the
it will be deployed by a majority of customers who have an LDP/MPLS background
as well. 

> However it might be better if this information were in IGP specific
> drafts put through the IGP WGs. Certainly I think that we need to
> specify more than this text since there are for example security
> and capability considerations.

if we go down the road of explicitly advertising the transport loopback
then i agree this work should be done in ospf-wg and isis-wg.
the question is wether we can go without protocol extension and
identify the loopback IP based on existing protocols.

> I have some explicit questions inline.
> 
> 
> On 12/12/2012 14:49, Hannes Gredler wrote:
>> clarence, stewart,
>> 
>> In favor of interoperable implementations i feel one should document how to
>> identify the transport IP address (in lieu of protocols extensions who would
>> explicitly advertise the transport IP addresses) to the PQ node for the 
>> targeted LDP session.
>> 
>> I am proposing to append the following text to 3.2. "Tunnel requirements":
>> 
>> 3.2.  Tunnel Requirements
>>    [ … ]
>> 
>>    When a failure is detected, it is necessary to immediately redirect
>>    traffic to the repair path.  Consequently, the repair tunnel used
>>    must be provisioned beforehand in anticipation of the failure.  Since
>>    the location of the repair tunnels is dynamically determined it is
>>    necessary to establish the repair tunnels without management action.
>>    Multiple repairs may share a tunnel end point.
>> 
>> <added-text>
>> 
>> Targeted LDP sessions are brought up using a pair of source (PLR) and 
>> destination
> What does PLR stand for?

This is the point of local repair (PLR) - 

>> (PQ node) loopback addresses. The following heuristics should be applied for 
>> deriving the
>> loopback IP address from a PQ nodes link-state advertisement.
>> 
>> for the IS-IS routing protocol:
>> 
>> A PLR router should connect to the address
>> 
>>  traffic-engineering deployments:
>>   - reported both in the TE-router ID TLV 134
>>   - and IP Reach TLVs (128,135) given that
>>   - the prefix length is /32
>> 
>>     or
>> 
>>  no traffic-engineering deployments:
>>   - reported both in the IP interface address TLV 132
>>   - and IP Reach TLVs (128,135), given that
>>   - there is only a single interface address advertised per the router
>>   - the prefix length is /32
>> 
> The text above does not scan (nor does the text below)
> 
>> for the OSPF routing protocol:
>> 
>> A PLR router should connect to the address
>> 
>>  traffic-engineering deployments:
>>   - reported in the Router Address TLV  (Type 10 LSA) and
>>   - router (Type 1 LSA) ) stub network  advertisement and
>>   - the address mask is 255.255.255.255
>> 
>>     or
>> 
>>  non-traffic-engineering deployments:
>>   - reported in the  router-id field of the Type-1 LSA)
>>   - the router (Type 1 LSA) stub network  advertisement and
>>   - the address mask is 255.255.255.255
>> 
>> </added-text>
> 


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