Re: MPLS TE Tunnel : Tunnel B/W doubt

Sonu

But the Head end Router l will choose only one path to the same Tail End
Router with only one Tunnel. Why it chooses two Tunnels ?

On Sun, Jan 29, 2012 at 10:12 PM, Sonu Khandelwal <sonu.kwl_at_gmail.com>wrote:

> Yes, for two path to the same destination two tunnels will be needed with
> two different explicit path.
>
> "tunnel mpls traffic-eng autoroute metric" to used to change the igp
> metric of the tunnel interface. By default tunnel's igp metric is the same
> as igp metric b/w source and destination.
>
> for e.g
>
> if tunnel source is 1.1.1.1 and tunnel destination is 3.3.3.3. Assume
> tunnel is not present and cost to reach from 1.1.1.1 to 3.3.3.3 is 10.
>
> Now when tunnel comes up, its metric will be 10.
>
> if you want this metric of 10 to be changed then you can use "tunnel mpls
> traffic-eng autoroute metric" to do the same thing.
>
> Thanks,
> Sonu
>
>
> On Sun, Jan 29, 2012 at 9:27 PM, CCIE KID <eliteccie_at_gmail.com> wrote:
>
>> 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)
>>
>>
>>
>

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