RSVP TE FRR

[gauravprakash]

Hi,

Can we create only One Hop Tunnel , as Primary tunnel and multi-hop backup Tunnel for RSVP TE FRR to achieve fastes convergence.

Cannot my RSVP TE FRR Primary  Tunnel pass more than one hop...and achieve the same results..

r1----r2---r3---r4

|                    |

|                    |

|                    |

r5----r6----r7---r8

My source is connected to r1 & destination r4..

I plan to make a Primary multihop tunnel from   r1   to  r4 with FRR function, and thebackup r1--r5--r66--r7--r8...

Will the failure of anylink between r1, r2, r3, r4 trigger  FRR on Primary Tunnel ( assuming interface supports sub-50ms failure detection )

Regards,

Gaurav Prakash

[amit.bhagat]

Hi Gaurav,

There are two types of FRR- NHOP and NNHOP. Next-Hop (NHOP) is used to protect a link and Next Next-Hop (NNHOP) is used to protect the next-hop.

In your case, the PLR (Point of Local Repair) is R1-router. However, the MP (Merge Point) is unknown. Here, both (Primary and Backup) tunnels are two different tunnels and the second tunnel can be made to work as a Backup tunnel but only in case of NHOP.

If your destination is connected to R4-router, I think you should implement NNHOP- protecting R2-router with R3-router as the Merge Point. The Backup tunnel will be through R1-R5-R6-R7-R3.

Please let us know how you go with this.

HTH.

Regards,

Amit.

[jcozzupoli]

Hi,

You would have to configure 2 TE Tunnels with Explicit paths as R1-R2-R3-R4 as primary and R1-R5-R6-R7-R8 as backup. To get superior fast convergence, I suggest you configure IS-IS as the IGP, as this is tweakable to easily acheive sub-50ms and even faster. I have implemented such solution and by tweaking the spf interval to the min (spf-interval 1 1 1) and also configured fast-flood to 2, this ensured extremely fast convergence and FRR failover and Fallback (even more important than failover). Of course configuring these tweaks, you'd have to ensure you have a very stable network, as such the implementation I ran was between 2 Data Centres with DWDM 10G links between them.

An Example Config for R1 would be as follows:

interface Tunnel100
ip unnumbered Loopback1
tunnel destination 44.44.44.44
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng autoroute announce
tunnel mpls traffic-eng priority 0 0
tunnel mpls traffic-eng bandwidth 5000
tunnel mpls traffic-eng path-option 1 explicit name TE_DIRECT
tunnel mpls traffic-eng fast-reroute
no routing dynamic
!
interface Tunnel200
ip unnumbered Loopback1
tunnel destination 88.88.88.88
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng priority 0 0
tunnel mpls traffic-eng bandwidth 5000
tunnel mpls traffic-eng path-option 1 explicit name TE_BACKUP
no routing dynamic
!

ip explicit-path name TE_DIRECT enable
next-address 2.2.2.1
next-address 3.3.3.2
next-address 4.4.4.3
!
ip explicit-path name TE_BACKUP enable
next-address 5.5.5.1
next-address 6.6.6.5
next-address 7.7.7.6
next-address 8.8.8.7

!

router isis
net 49.0001.1111.1111.1111.00
is-type level-2-only
metric-style wide
fast-flood 2
spf-interval 1 1 1
mpls traffic-eng router-id Loopback1
mpls traffic-eng level-2
!

HTH

Joe.

[ulatif]

You have topology:

r1------r2-----r3-----r4

So you want to create a backup (FRR tunnel) such that a failure on the LSP between R1 -> R4 is protected by an FRR tunnel ? Is that your requirement?

FRR will not work in this scenario since you're not adhering to NHOP (link) or NNHOP (node) protection. PLR and MP are too far away

[jcozzupoli]

Hi,

Yes I agree with Usman on this. With what you are asking isn't possible, I think you need to explain better what you are wanting to try to do and then we will be able to help you better.

Thanks,

Joe.

[gauravprakash]

yes, what I want to achieve this with FRRin my below setup

Primary Tunnel :  Source & Destination are  3-4 hops away

Backup Tunnel :  Source & Destination are  6-7 hops away

I want sub-50ms protection , my interfaces of routers supports detection of failure in less than 50ms.

Is it possible ?

If Not , what else is the way

Thx to all ..

Rgds,

Gaurav Prakash

[jcozzupoli]

Hi Gaurav,

Yes that is acheivable, if you look at the example configurations I gave you, and have your IGP tweaked (IS-IS for best resuls there), then having a backup tunnel with sub-50ms failover is very acheivable.

Thanks,

Joe.

[ulatif]

No it won't work.

..unless you create more than one backup tunnels.

The maximum links you can protect with FRR = 2 and maximum nodes you can protect with FRR = 1

What you are asking may be possible with path-protection but it wont be FRR (so convergence won't be 50ms).

rgds,

Usman