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Bronze

Forward traffic on DS-MPLS TE tunnel ?

Hi Team,

As per my understanding, DS TE tunnel will look for sub-pool bandwidth on every interface via RSVP. And this works fine when the entire path is configured with appropriate DiffServ QoS scheduling. So the traffic forwarded via DS-TE is like normal TE tunnel. i.e. either via Static routing, Policy Based Routing or Autoroute announce.

But below are my requirements in my case:

There are two nodes A and B. There exists two different paths (Path 1 and Path 2) to reach between them and I have normal TE tunnel via Path 1 and DS-TE tunnel via Path 2. From the tunnel head end (i.e. Node-A) I would like to forward packets marked with Precedence 5, 6 and 7 via DS-TE tunnel (via Path 2) and the rest of the traffic will be forwarded via Path 1. Is it possible to do this kind of routing.

Hope im clear in my understanding.

thanks in advance.

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Forward traffic on DS-MPLS TE tunnel ?

Arunkumar,

Can you post the configuration for the 3 tunnels.

The master tunnel is only required on platforms running 12.2SR code. That would include 7600 running 12.2SRA, SRB or SRC.

It is simply a logical decoupling, which makes you configure the exp values on the member tunnels and the routing information (autoroute announce, forwarding adjacencies, static route, PBR, etc) on the master tunnel.

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
8 REPLIES
Cisco Employee

Re: Forward traffic on DS-MPLS TE tunnel ?

Arunkumar,

It is indeed possible to accomplish what you are describing using a feature called Class Based Tunnel Selection (CBTS). Please refer to the following document for more information on this feature:

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/gscbts.html

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Bronze

Re: Forward traffic on DS-MPLS TE tunnel ?

Hi Harold,

Thanks for your reply. I ve set up three tunnels between two nodes. Tunnel 0 -- configured to carry EXP 5 traffic

Tunnel 1 -- configured to carry EXP4 traffic

Tunnel 2 -- configured to carry default traffic.

Tunnels are up, but i m seeing EXP 4 and default traffic is taking only tunnel 0.

One more thing, what is Master tunnel configured for. I m not able to understand the concept of Master Tunnel's role in CBTS.

thanks in advance.

Cisco Employee

Re: Forward traffic on DS-MPLS TE tunnel ?

Arunkumar,

Can you post the configuration for the 3 tunnels.

The master tunnel is only required on platforms running 12.2SR code. That would include 7600 running 12.2SRA, SRB or SRC.

It is simply a logical decoupling, which makes you configure the exp values on the member tunnels and the routing information (autoroute announce, forwarding adjacencies, static route, PBR, etc) on the master tunnel.

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Bronze

Re: Forward traffic on DS-MPLS TE tunnel ?

Hi Harold,

Thanks for your valuable response.

It is working fine in 7206 running with code SBC.

But in GSR (GRP) with code: "gsr-k4p-mz.120-32.SY4.bin" we are able to configure the "tunnel mpls traffic-eng exp " command but CBTS is not working. While checked in Cisco FN, there is no support for this feature.

Cisco Employee

Re: Forward traffic on DS-MPLS TE tunnel ?

Arunkumar,

As far as I am aware of, CBTS is only supported on the E5 on the GSR.

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Bronze

Re: Forward traffic on DS-MPLS TE tunnel ?

Hi Harold,

When it means "CBTS support is only on Engine 5 Linecards of GSR, does it mean,

1) All the TE tunnels intermediate hops and interfaces should be Engine 5 or

2) Traffic should hit the Engine 5 LineCard of GSR then only it look for CBTS MPLS-TE.

In our case we have multiple GSR's (P) connected on Engine 5 LC. But GSR's are connected to PE routers on Engine 3 LC. So obviously traffic from PE router (already marked with MPLS EXP bits) will hit the GSR (P) on Engine 3 and there is end to end MPLS TE tunnels with CBTS (built over Engine 5 and Engine 3 LC). So in this case MPLS-TE CBTS will work or not? Kindly refer the attached diagram.

Cisco Employee

Re: Forward traffic on DS-MPLS TE tunnel ?

Arunkumar,

You should only be concerned about interfaces being used as egress interfaces for the tunnels on the head-end router, which is where the CBTS feature is being applied.

The rest of the network only needs to support MPLS TE.

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Forward traffic on DS-MPLS TE tunnel ?

Arun,

It is a bug

CSCsm55274

Symptoms: Class Based Tunnel Selection (CBTS) stops working. Packets are sent through the wrong tunnel.

Conditions: This symptom is observed when the tunnel flaps.

Workaround: There is no workaround. Once CBTS is broken, only a reload of the Line card clears the problem.

Though Cisco says it is resolved in SY6 it is not the case...

Regards,

Prakash

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