[j-nsp] Routing-instances

Sean Clarke sean at clarke-3.demon.nl
Wed Sep 20 11:09:32 EDT 2006


Hi Christian,

  If you have that t3-x interface in a routing-instance, it will then
  be in a different routing table, i.e. not inet0 . As t1-x I guess is
  in inet0, then you will always use that interface to forward
  traffic.  t3 interface in not known in the master routing table.
  

Cheers
Sean
--

Not so long ago you wrote : 
CK> That's what I assumed..thanks for your help guys..

CK> Heres another ques..

CK> I had an issue today I'll explain briefly

CK> A customer had t3 and t1..t3 was to be preferred and t1 I set a metric
CK> of 220 on in case the t3 fails.. (these are on2  diff routers, t3 is on
CK> the juniper and t1 on the cisco)

CK> Static route for t3 on juniper..but traffic was preferring the t1
CK> still..

CK> Then I found the routing instance statement at the end of the config,
CK> but it did look like it was complete

CK> }
CK> routing-instances {
CK>     routing-instances {
CK>         interface t3-5/1/1.0;
CK>     }
CK> }
CK> Now, any clue as why the traffic was preferring the t1 link?

CK> Was it because the routing instance was not configured correctly? (I do
CK> not know who added it or why it was..)

CK> Thanks!



CK>  

CK> -----Original Message-----
CK> From: Leigh Porter [mailto:leigh.porter at ukbroadband.com] 
CK> Sent: Wednesday, September 20, 2006 10:46 AM
CK> To: Erdem Sener
CK> Cc: Christian Koch; juniper-nsp at puck.nether.net
CK> Subject: Re: [j-nsp] Routing-instances


CK> They are also used for filter based forwarding.
CK> i.e.

CK> You match packets to port 80 and have a routing instance with a default
CK> route pointing to your transparent WWW cache, when the filter sees a
CK> datagram matching your filter instead of using the normal inet.0 routing
CK> table you can tell it to use a different routing table to select a route
CK> from for that datagram.

CK> Or say you have two upstream ISP connections, you can decide what ISP to
CK> send traffic to based on a filter and have each ISP with a different
CK> routing instance, I think this is the example used in the Juniper docs.

CK> Juniper routing instances can have their own routing protocol instances
CK> also, I believe.

CK> --
CK> Leigh


CK> Erdem Sener wrote:
>> Hello,
>>
>>  Well, basically the routing-instances are routing tables besides the 
>> default inet.x and might be used for things like source-based routing,

>> MPLS/VPLS configuration etc.
>>
>>  By configuring a routing-instance you might be defining a VRF table, 
>> a VPLS domain or just a routing table you can use for source-based 
>> routing.
>>
>> HTH
>> --
>> Erdem
>>
>>
>>
>> On 9/20/06, Christian Koch <ckoch at globix.com> wrote:
>>   
>>> Can anyone explain to me exactly what "routing-instances" are?
>>>
>>> Thanks!
>>>
>>>
>>>
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