Re: MPLS TE Tunnel : Tunnel B/W doubt

Gaurav

Dude one new doubt man

To reach a particular Tail end router, there should be only route.

In regular SPF, the result of path computation may be two equal cost
multipaths (ECMP) to a destination. However, the result of CSPF is always
one path to the tailend router. In case, two paths are equal, CSPF has 3
rules followed sequentially to break the tie:

*a.* Take the path with largest minimum available bandwidth

*b.* Take the path with the lowest hop-count (number of routers in the path)

*c.* Take one path at random.

So there should be only one path to a TAIL END router.. How does it has two
paths for a same TAILEND router. via two different TE TUNNELS.

On Sun, Jan 29, 2012 at 8:44 PM, CCIE KID <eliteccie_at_gmail.com> wrote:

> Gaurav
>
> Tats gr8 mate .. I will also check the purpose of it and let u know
> buddy..
> Till then study hard
>
>
>
> On Sun, Jan 29, 2012 at 8:33 PM, GAURAV MADAN <gauravmadan1177_at_gmail.com>wrote:
>
>> Kid
>>
>> Everything you said is exactly what i understand this topic :)
>> We are on same page .
>>
>> I will simulate the usage of metric command and try to post results ,
>>
>> Till then .. thnx
>>
>> Gaurav Madan
>>
>>
>> On Sun, Jan 29, 2012 at 7:39 PM, CCIE KID <eliteccie_at_gmail.com> wrote:
>>
>>> Gaurav
>>>
>>> TE Auto Route Announce will just make ur OSPF learned LSA's from the
>>> Tunnel Tail End to utitlize the Tunnel path to reach all the networks
>>> behind the Tunnel Tail End Router. It has nothing to do with priority
>>> levels for each tunnel
>>> U can assign priorities to each tunnel and then tat take over the
>>> appropriate B.W. available in the interface if it has highest priority
>>>
>>> In ur case both ur tunnels has both set up and hold priority has 7 and 7
>>> 7 and 7 is the least priority tat u can assign to a tunnel and both the
>>> tunnels has the same priority and both r pointing to the same tunnel tail
>>> end and also u r running Auto Route Announce on both the tunnels
>>>
>>> But the only difference between the two tunnels is the Bandwidth and to
>>> form the two tunnels it requires 60 and 70 kbps end to end to form the
>>> tunnel. So atleast the B.W of the end to end path should be atleast 130kpbs
>>>
>>> So now OSPF will carry the TE information like the requested B.W and
>>> also other TE colors associated with TE in its Opaque LSA Type 9 ,10 and
>>> 11. depends upon it is a Single Area OSPF or Multi Area and also it is
>>> within the Single AS. If the Head end sees that it has enough B.W. then the
>>> Path message from Head end to Tail End and Reserve message from the Tail
>>> End to head End is succesfull , the tunnel will be up.
>>>
>>> if there is any change in the available BW in that particular end to end
>>> path, it will be conveyed by OSPF and it triggers the Path message and
>>> Reserve message
>>>
>>> In ur setup
>>>
>>> U r obviously u r going to see two paths to reach the tail-end router
>>> via these two tunnels and there will be Unequal cost LOAD balancing . If u
>>> want to prioritize one tunnel over another one , just change the metric of
>>> the tunnel rather than the BW
>>> Because B.W inside the tunnel doesnt reflect ur BEST METRIC to reach a
>>> particular TE Tail End
>>>
>>> So ultimately u have many paths to the Same tail end router ie via
>>> different tunnels.So ultimately it all depends upon how much BW is required
>>> to form the tunnel . Int his case , there will 70:60 ratio of traffic going
>>> from one tunnel to another tunnel.
>>>
>>> If u dont want to see Unequal Cost Load Balancing, u have to do Policy
>>> Routing rather than using AutoRoute Announce.
>>>
>>> But I am not sure about this command
>>>
>>> tunnel mpls traffic-eng autoroute metric
>>>
>>> If u give this command whether one tunnel will be preferred over another
>>> tunnel if ur Tail End Router address are same.
>>>
>>> Post me about this command dude
>>>
>>> Hope this helps
>>>
>>>
>>>
>>>
>>>
>>> On Sun, Jan 29, 2012 at 1:24 AM, Naveen <navin.ms_at_gmail.com> wrote:
>>>
>>>> Yes. What you have is already doing UELB (unequal cost load balancing
>>>> in
>>>> the ratio 6:7) also across TE tunnels. Try sending some traffic end to
>>>> end,
>>>> and check the TE counters.
>>>>
>>>> If your intention is not to load balancing at all, then remove
>>>> "autoroute
>>>> announce", and then route traffic to the tunnel you want with a local
>>>> policy.
>>>>
>>>>
>>>> On Sat, Jan 28, 2012 at 11:31 AM, GAURAV MADAN <
>>>> gauravmadan1177_at_gmail.com>wrote:
>>>>
>>>> > Naveen ,
>>>> >
>>>> > Thnx for the reply ..
>>>> > Do you mean to suggest some kind of unequal load-balancing across
>>>> various
>>>> > TE tunnels .
>>>> >
>>>> > Between the tunnels ; I can choose using following command :
>>>> >
>>>> > Router(config-if)#tunnel mpls traffic-eng autoroute metric
>>>> >
>>>> > I can set one tunnel as lower metric to be announced over the second
>>>> > tunnel . and hence play around with this
>>>> >
>>>> > Is that what u r suggesting ?
>>>> >
>>>> >
>>>> > Gaurav Madan
>>>> >
>>>> >
>>>> >
>>>> > On Sun, Jan 29, 2012 at 12:32 AM, Naveen <navin.ms_at_gmail.com> wrote:
>>>> >
>>>> >> What you are seeing is Load balancing across multiple TE tunnels for
>>>> >> prefixes reachable further down the tunnel. This is an expected
>>>> behavior
>>>> >> with "autoroute announce". You can use "auto-bw" to dynamically
>>>> control the
>>>> >> TE tunnel Bandwidth after tunnel setup.
>>>> >>
>>>> >> Once tunnels are established (using CSPF), IGP considers the Tunnels
>>>> as
>>>> >> always 1-hop (and always prefers over any other IGP 1-hop path). You
>>>> can
>>>> >> load balance upto 8,16, or 32 TE paths as supported by the platform.
>>>> >>
>>>> >>
>>>> >>
>>>> >> On Sat, Jan 28, 2012 at 10:13 AM, Sonu Khandelwal <
>>>> sonu.kwl_at_gmail.com>wrote:
>>>> >>
>>>> >>> [image: Boxbe] <https://www.boxbe.com/overview> Sonu Khandelwal (
>>>> >>> sonu.kwl_at_gmail.com) is not on your Guest List<
>>>> https://www.boxbe.com/approved-list>| Approve
>>>> >>> sender <https://www.boxbe.com/anno?tc=10557674166_204049186> |
>>>> Approve
>>>> >>> domain <https://www.boxbe.com/anno?tc=10557674166_204049186&dom>
>>>>
>>>> >>>
>>>> >>> on interface it means how much bandwidth can be reserved by RSVP.
>>>> >>> on tunnel it means, how much bandwidth is required by tunnel.
>>>> >>>
>>>> >>> Hope it helps.
>>>> >>>
>>>> >>> Thanks,
>>>> >>> Sonu
>>>> >>>
>>>> >>> On Sat, Jan 28, 2012 at 11:37 PM, GAURAV MADAN <
>>>> >>> gauravmadan1177_at_gmail.com>wrote:
>>>> >>>
>>>> >>> > Then what does "rsvp bandwidth <> " on interface does ?
>>>> >>> > That is also a constraint on interface to establish the tunnel ..
>>>> >>> right ?
>>>> >>> >
>>>> >>> > How do you differentiate between the BW that we specify on
>>>> interface
>>>> >>> level
>>>> >>> > and the one that we specify on interface tunnel ?
>>>> >>> >
>>>> >>> > Thnx
>>>> >>> > Gaurav Madan
>>>> >>> >
>>>> >>> > On Sat, Jan 28, 2012 at 9:23 PM, Paul Negron <
>>>> negron.paul_at_gmail.com>
>>>> >>> > wrote:
>>>> >>> >
>>>> >>> > > The bandwidth is a constraint. It only says " I need 60K of
>>>> >>> bandwidth in
>>>> >>> > > order to establish this tunnel". One tunnel requires 60K and the
>>>> >>> other
>>>> >>> > > requires 70K. If the bandwidth is available for both, they will
>>>> both
>>>> >>> be
>>>> >>> > > established. That "bandwidth" constraint has nothing to do with
>>>> the
>>>> >>> cost
>>>> >>> > of
>>>> >>> > > the tunnel for route selection.
>>>> >>> > > --
>>>> >>> > > Paul Negron
>>>> >>> > > CCIE# 14856 CCSI# 22752
>>>> >>> > > Senior Technical Instructor
>>>> >>> > >
>>>> >>> > >
>>>> >>> > >
>>>> >>> > > > From: GAURAV MADAN <gauravmadan1177_at_gmail.com>
>>>> >>> > > > Reply-To: GAURAV MADAN <gauravmadan1177_at_gmail.com>
>>>> >>> > > > Date: Sat, 28 Jan 2012 20:44:46 +0530
>>>> >>> > > > To: Cisco certification <ccielab_at_groupstudy.com>
>>>> >>> > > > Subject: MPLS TE Tunnel : Tunnel B/W doubt
>>>> >>> > > >
>>>> >>> > > > Hi All
>>>> >>> > > >
>>>> >>> > > > I am running in some issue to understand how Tunnel Bandwidth
>>>> >>> works .
>>>> >>> > > >
>>>> >>> > > > Topology
>>>> >>> > > > ---------
>>>> >>> > > >
>>>> >>> > > > R1 R4
>>>> >>> > > > | |
>>>> >>> > > > | |
>>>> >>> > > > R2-----------------R3
>>>> >>> > > >
>>>> >>> > > > R1 is head end of tunnel . It has 2 tunnels Tunnel0 and
>>>> Tunnel 1 as
>>>> >>> > > follows
>>>> >>> > > > :
>>>> >>> > > >
>>>> >>> > > > R1#sh run int tun 0
>>>> >>> > > > Building configuration...
>>>> >>> > > >
>>>> >>> > > > Current configuration : 284 bytes
>>>> >>> > > > !
>>>> >>> > > > interface Tunnel0
>>>> >>> > > > ip unnumbered Loopback0
>>>> >>> > > > tunnel mode mpls traffic-eng
>>>> >>> > > > tunnel destination 4.4.4.4
>>>> >>> > > > tunnel mpls traffic-eng autoroute announce
>>>> >>> > > > tunnel mpls traffic-eng priority 7 7
>>>> >>> > > > tunnel mpls traffic-eng bandwidth 70
>>>> >>> > > > tunnel mpls traffic-eng path-option 1 dynamic lockdown
>>>> >>> > > > end
>>>> >>> > > >
>>>> >>> > > > R1#sh run int tun 1
>>>> >>> > > > Building configuration...
>>>> >>> > > >
>>>> >>> > > > Current configuration : 284 bytes
>>>> >>> > > > !
>>>> >>> > > > interface Tunnel1
>>>> >>> > > > ip unnumbered Loopback0
>>>> >>> > > > tunnel mode mpls traffic-eng
>>>> >>> > > > tunnel destination 4.4.4.4
>>>> >>> > > > tunnel mpls traffic-eng autoroute announce
>>>> >>> > > > tunnel mpls traffic-eng priority 7 7
>>>> >>> > > > tunnel mpls traffic-eng bandwidth 60
>>>> >>> > > > tunnel mpls traffic-eng path-option 1 dynamic lockdown
>>>> >>> > > >
>>>> >>> > > >
>>>> >>> > > >
>>>> >>> > > > Now ; one tunnel has bandwidth of 70Kbps and other has of
>>>> 60Kbps .
>>>> >>> > > > Following is my show ip route ospf output :
>>>> >>> > > >
>>>> >>> > > > 4.0.0.0/32 is subnetted, 1 subnets
>>>> >>> > > > O 4.4.4.4 [110/4] via 4.4.4.4, 00:05:52, Tunnel1
>>>> >>> > > > [110/4] via 4.4.4.4, 00:05:52, Tunnel0
>>>> >>> > > >
>>>> >>> > > > I see both entries there ...
>>>> >>> > > >
>>>> >>> > > > Is there a reason for this ?
>>>> >>> > > > Please let me know .. I think that it should be routing via
>>>> Tunnel
>>>> >>> 0
>>>> >>> > > only .
>>>> >>> > > >
>>>> >>> > > > Thanks
>>>> >>> > > > Gaurav Madan
>>>> >>> > > >
>>>> >>> > > >
>>>> >>> > > > Blogs and organic groups at http://www.ccie.net
>>>> >>> > > >
>>>> >>> > > >
>>>> >>>
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>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> With Warmest Regards,
>>>
>>> CCIE KID
>>> CCIE#29992 (Security)
>>>
>>>
>>>
>>
>
>
> --
> With Warmest Regards,
>
> CCIE KID
> CCIE#29992 (Security)
>
>
>

-- 
With Warmest Regards,
CCIE KID
CCIE#29992 (Security)
Blogs and organic groups at http://www.ccie.net