Subject: [lisp] Question on draft-ietf-lisp-11.txt

From: Mathieu Peresse <[email-masked]>
Date: Wed, 20 Apr 2011 12:01:39 +0200 (CEST)

Hi,

section 6.1.5 (EID-to-RLOC UDP Map-Reply Message) states:

   When an ETR is configured with overlapping EID-prefixes, a Map-
   Request with an EID that longest matches any EID-prefix MUST be
   returned in a single Map-Reply message.  For instance, if an ETR had
   database mapping entries for EID-prefixes:

     10.0.0.0/8
     10.1.0.0/16
     10.1.1.0/24
     10.1.2.0/24

   A Map-Request for EID 10.1.1.1 would cause a Map-Reply with a record
   count of 1 to be returned with a mapping record EID-prefix of
   10.1.1.0/24.

   A Map-Request for EID 10.1.5.5, would cause a Map-Reply with a record
   count of 3 to be returned with mapping records for EID-prefixes
   10.1.0.0/16, 10.1.1.0/24, and 10.1.2.0/24.

I don't understand how 10.1.5.5 longest matches 10.1.1.0/24 and 10.1.2.0/24 ?
It would match with a /16 mask in the request but the requested mask is not mentionned so
I assume it is a /32...

am I missing something ?

-- 
Mathieu

---

From: Luigi Iannone <[email-masked]>
Date: Wed, 20 Apr 2011 12:20:12 +0200

>   database mapping entries for EID-prefixes:

If you store only 10.1/16 what will happen if later on you have a packet destined to 10.1.1.69?
It will match 10.1/16 without generating any cache-miss, but this means that the wrong mapping is used, since you should use 10.1.1.0/24.

That's why you need the other two.

Luigi

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