The MPLS-OPS Archive

[Rajiv Asati <rajiva@cisco.com>]

Hi,

Please see inline...
At 12:03 PM 7/18/2002, M. ELK wrote:
> Hi 
>  
> For the case that customer carrier sites is pure IP . 
> Customer carrier say CSC-CE1 is advertising internal route (/32) in site
> 1 to
> backbone carrier CSC-PE1  using IPV4BGP label distribution . 
>  
> Case 1 : 
>  Those internal routes are part of the IGP and using  BGP
> "network" statements on CSC-CE1 to be included in the BGP table
> . 
>  
> Is CSC-CE1 advertise :
> 1) a different label value to each internal routes 

If those internal routes are learned via IGP, then each will be
advertised with the unique label. In other words, CsC-CE will have a
unique local label.

> Or 
> 2)"Implicit_Null" as label for all internal routes . 

If those internal routes are "connected" routes, then they will
be advertised with "imp-null" label. 

>  
> If "1" : At CSC-CE1 what wil be the label action assigned
> .
>          is it A-
> "Untag" 
>               
> Or 
>               
> B- "Aggregate" . 

If the CE is not running MPLS with other C router, then the outgoing
label for such routes should be untagged.
Unless summarization is being done (in the network statement of BGP), the
"aggregate" label should not be present.

>  
> Case2 : 
>  Each node in Site1 will have L0 amd L1 address .
>  L0 is known via the IGP but not L1 . 
>  Each node propagate L1 through iBGP full mesh 
>   (all nodes in site1 run iBGP) 
>  CSC-CE1 will propagate L1's for all internal nodes to CSC-PE1 .
>   
>   Same enq as case1 ,ie: CSC-CE1 behaviour as "1A"
> ,"1B" or "2" .

The CsC-CE1 should have a unique local label for each of the L1(s) and
should have an outgoing label

        

- untagged
if the CE routing is not running MPLS with the C router(s)

        

- valid
label if the CE is running MPLS with the C router 

Of course, if the CE does the summarization for those L1(s), then there
will be one entry for that summarized route  (unique label/aggregate
outgoing label).

>  
>  Case2 is included to see if the internal routes are  leraned
> through 
>   different way (IGP or iBGP) will influenece CSC-CE1 behaviour .

Not really.  Unless you are also doing ipv4+label distribution in
the iBGP.

>   
>   I guess that all ( "1A","1B" or "2")
> are workable ,but "1B" is 
>   less efficient than "2" 

I would agree to that.

> and "1A" is better than
> "2" . 

Depends. 
It is really upto the end-user which way he/she wants to go. If one
doesn't want to do redistribution (IGP to BGP and vice versa), then
"network" statements in the BGP makes the life simpler.
Or one could redistribute along with filtering.


Hope this helps. Please feel free, if you have further Q.

Cheers,
Rajiv

>   Iintersted to know  what the
> method selected by the major manufacturer .

 
 
Brgds
 
 
 

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