[j-nsp] MPLS OAM not triggering LSP

Wed Apr 25 06:13:29 EDT 2007

Hi Sinan,

Current version of JunOS that you are using, logs an error message when LSP goes down because of BFD as mentioned in page-191 of the following doc. However it doesn't make the LSP down.

http://www.juniper.net/techpubs/software/junos/junos81/swconfig81-mpls-apps/download/swconfig81-mpls-apps.pdf

thanks,
-sail

-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Sinan Ilkiz
Sent: Wednesday, April 25, 2007 1:55 AM
To: juniper-nsp at puck.nether.net
Subject: [j-nsp] MPLS OAM not triggering LSP

Hi all,

We are trying to achieve fast convergence times for one of our links. We can not detect link failures in this link directly, i.e. interface never goes down in case of failures. We decided that we can benefit from BFD for LSPs. We are testing this configuration;

label-switched-path lsp_to_bt_j_2_sifir {
    from 192.168.100.1;
    to 192.168.100.2;
    ldp-tunneling;
    no-cspf;
    link-protection;
    primary via_sifir {
        oam {
            bfd-liveness-detection {
                minimum-interval 300;
                multiplier 3;
            }
        }
    }
}

When we simulate an indirect failure, we see that BFD session goes down but LSP's path does not change. So this causes extended downtimes as long as RSVP states time out. We couldn't find out what we are doing wrong. In my opinion, when BFD detects the failure, it should signal to the local router and say "this path is no longer available, you should find another way". We tested both secondary standby and link-protection options but nothing changed. We used both 7.6R4 and 8.1R3. Test lab consists of one m7i and J4300 connected via their ethernet links.

M7i === switch1 === switch2 === J4300

One ethernet link is used as LSP path and other is used as backup link. Switch configuration is done in such a way that (using VLANs) fe-1/3/0 of M7i and fe-0/0/0 of J4300 form the first path; fe-1/3/1 of M7i and fe-0/0/1 of J4300 form second path. To simulate a failure we plug off the fist cable between switch1 and switch2 so neither M7i nor J4300 knows this problem directly and only the first path (between fe-1/3/0 and fe-0/0/0) is affected. This way, we tried to simulate an indirect failure.

lab at BT-M-1> show mpls lsp ingress extensive    
Ingress LSP: 1 sessions

192.168.100.2
  From: 192.168.100.1, State: Up, ActiveRoute: 0, LSPname: lsp_to_bt_j_2_sifir
  ActivePath: via_sifir (primary)
  Link protection desired
  LoadBalance: Random
  Encoding type: Packet, Switching type: Packet, GPID: IPv4
 *Primary   via_sifir        State: Up
    SmartOptimizeTimer: 180
    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
          10.1.1.2(Label=3)
    OAM state : BFD session up   LSP-ping up
    5 Apr 25 08:34:23.102 Link-protection Up
    4 Apr 25 08:33:29.085 Selected as active path
    3 Apr 25 08:33:29.084 Record Route:  10.1.1.2(Label=3)
    2 Apr 25 08:33:29.084 Up
    1 Apr 25 08:33:29.073 Originate Call
  Created: Wed Apr 25 08:33:28 2007
Total 1 displayed, Up 1, Down 0

Then we plug off the appropriate cable at "2007-04-25 08:37:55 UTC"

lab at BT-M-1> show mpls lsp ingress extensive    
Ingress LSP: 1 sessions

192.168.100.2
  From: 192.168.100.1, State: Up, ActiveRoute: 0, LSPname: lsp_to_bt_j_2_sifir
  ActivePath: via_sifir (primary)
  Link protection desired
  LoadBalance: Random
  Encoding type: Packet, Switching type: Packet, GPID: IPv4
 *Primary   via_sifir        State: Up
    SmartOptimizeTimer: 180
    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
          10.1.1.2(Label=3)
    OAM state : BFD session not up   LSP-ping up
    7 Apr 25 08:38:01.917 Link-protection Up
    6 Apr 25 08:38:01.914 Link-protection Down
    5 Apr 25 08:34:23.102 Link-protection Up
    4 Apr 25 08:33:29.085 Selected as active path
    3 Apr 25 08:33:29.084 Record Route:  10.1.1.2(Label=3)
    2 Apr 25 08:33:29.084 Up
    1 Apr 25 08:33:29.073 Originate Call
  Created: Wed Apr 25 08:33:28 2007
Total 1 displayed, Up 1, Down 0

LSP is still traversing the down link. After a short while,

lab at BT-M-1> show mpls lsp ingress extensive            
Ingress LSP: 1 sessions

192.168.100.2
  From: 192.168.100.1, State: Up, ActiveRoute: 0, LSPname: lsp_to_bt_j_2_sifir
  ActivePath: via_sifir (primary)
  Link protection desired
  LoadBalance: Random
  Encoding type: Packet, Switching type: Packet, GPID: IPv4
 *Primary   via_sifir        State: Up
    SmartOptimizeTimer: 180
    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
          10.1.1.6
    OAM state : BFD session not up   LSP-ping up
   11 Apr 25 08:38:38.265 Record Route:  10.1.1.6
   10 Apr 25 08:38:38.264 Record Route:  10.1.1.6
    9 Apr 25 08:38:35.237 Tunnel local repaired
    8 Apr 25 08:38:35.237 Down
    7 Apr 25 08:38:01.917 Link-protection Up
    6 Apr 25 08:38:01.914 Link-protection Down
    5 Apr 25 08:34:23.102 Link-protection Up
    4 Apr 25 08:33:29.085 Selected as active path
    3 Apr 25 08:33:29.084 Record Route:  10.1.1.2(Label=3)
    2 Apr 25 08:33:29.084 Up
    1 Apr 25 08:33:29.073 Originate Call
  Created: Wed Apr 25 08:33:28 2007
Total 1 displayed, Up 1, Down 0

So it takes for LSP to switch to backup path from 08:37:55 to 08:38:38. I couldn't find a logical explanation why BFD does not trigger LSP.

Anyone of you tried to use MPLS OAM and hit the same problem?

Regards.
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