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Beginner

L2 Bundle interface load-balancing problem on Cisco ASR9K

Hello everyone,

We're having a little issue which we've been struggling with over the past few days.


We have a PE with a LACP L2 bundle-ethernet interface comprised of two GigabitEthernet physical interfaces, which are facing customer equipment. We provide a L2VPN tagged service, so such bundle acts as one end of a pseudowire over MPLS.

The problem is that we can't manage to balance the traffic over both members of the bundle in the outbound direction; there's only one link being used while the other remains idle no matter the traffic load on the "working" interface, which gets to a point of saturation. The ingress traffic, however, is correctly balanced.

According to our current l2vpn and bundle-ether configurations the hash calculation for the load-balance should be done based on src-ip-dst calculations, as pointed out in the following article:

asr9000-xr-load-balancing-architecture-and-characteristics/ta-p/3124809

 

So please, if anyone could shed some light over this matter we'd be greatly thankful.

 

We share our current PE configuration scripts (of the interfaces and l2vpn) in the following lines:

 

interface Bundle-Ether100
mtu 9216
bundle load-balancing hash dst-ip
!

interface Bundle-Ether100.200 l2transport
encapsulation dot1q 200
!

interface GigabitEthernet0/0/1/0
bundle id 100 mode active
!

interface GigabitEthernet0/0/1/1
bundle id 100 mode active
!


l2vpn
load-balancing flow src-dst-ip
pw-class mpls
encapsulation mpls
!
!
xconnect group Transport
p2p Transport
interface Bundle-Ether100.200
neighbor ipv4 10.1.200.2 pw-id 200
pw-class mpls
!
!
!
!


And here's some troubleshooting info that could be useful:

 

 

  • Monitor interface, where we can see how the traffic is correctly balanced at the ingress but not at the eggress:
RP/0/RSP0/CPU0:router-pe#monitor interface
Protocol:General
Interface             In(bps)      Out(bps)     InBytes/Delta  OutBytes/Delta
BE100.200            (statistics not available)
BE100                 46.1M/  2%   545.7M/ 27%    53.2T/13.4M    642.9T/133.5M
Gi0/0/1/0             23.1M/  2%   547.3M/ 54%    26.6T/6.0M     638.3T/145.9M
Gi0/0/1/1             23.2M/  2%    21000/  0%    26.6T/6.0M       4.6T/518

 

  • Some info about the load-balancing:
RP/0/RSP0/CPU0:router-pe#show bundle load-balancing bundle-ether 100 detail location 0/0/CPU0

Bundle-Ether100
  Type:                  Ether (L3)
  Members <current/max>: 2/64
  Total Weighting:       2
  Load balance:          Dst IP
  Locality threshold:    65
  Avoid rebalancing?     False
  Sub-interfaces:        1

  Member Information:
    Port:                 LON  ULID  BW
    --------------------  ---  ----  --
    Gi0/0/1/0               0     0   1
    Gi0/0/1/1               1     1   1

  Sub-interface Information:
    Sub-interface                 Type  Load Balance  Locality
                                        Hash          Threshold
    ----------------------------  ----  ------------  ---------
    Bundle-Ether100.200           L2    Dst IP               65

  Platform Information:
  =====================

                  * Bundle Summary Information *
                    --------------------------

Interface              : Bundle-Ether100       Ifhandle           : 0x000001a0
Lag ID                 : 3                     Virtual Port       : 255
Number of Members      : 2                     Local to LC        : Yes
Hash Modulo Index      : 2
MGSCP Operational Mode : No

Member Information:
LON        Interface       ifhandle     SFP   port   slot remote/rack_id
-----   ---------------   ----------    ---   ----   ---- --------------
0       Gi0/0/1/0         0x040002c0     96     16      2       0/0
1       Gi0/0/1/1         0x04000300     99     17      2       0/0

Preroute Member Information:
LON        Interface       ifhandle     SFP   port   slot remote/rack_id
-----   ---------------   ----------    ---   ----   ---- --------------
1       Gi0/0/1/1         0x04000300     99     17      2       0/0

                   * Bundle Table Information *
                     ------------------------

[NP 0]:
----------------------------------------------------------------------
    Unicast (Global) LAG table     |     Unicast  (Rack) LAG table
----------------------------------------------------------------------
 idx  local    VQI   port   VQI-LB | idx  local   VQI   port   VQI-LB
----------------------------------------------------------------------
  1      0     96     16      0       1      0     96     16      0
  2      0     99     17      0       2      0     99     17      0

[NP 1]:
-------------------------------------------------------------------------------------------------------------
    Unicast (Global) LAG table     |    Multicast (Local) LAG table    |    Unicast (Rack) LAG table
-------------------------------------------------------------------------------------------------------------
 idx  local    VQI   port   VQI-LB | idx  local    VQI   port   VQI-LB | idx  local    VQI   port   VQI-LB
-------------------------------------------------------------------------------------------------------------
   1      1     96     16      0       1      1     96     16      0       1      1     96     16      0
   2      1     99     17      0       2      1     99     17      0       2      1     99     17      0

                   * SW LAG Table Information *
                     ------------------------

--------------------------------------------------------------------------------------
          Global/Rack  LAG table          |             Local LAG table
--------------------------------------------------------------------------------------
 idx  local    LON    VQI   port   VQI-LB | idx  local    LON    VQI   port   VQI-LB
--------------------------------------------------------------------------------------
   1      1      0     96     16      0     1      1      0     96     16      0
   2      1      1     99     17      0     2      1      1     99     17      0

===============================================================================

 

  • And some information about the pseudowire:
RP/0/RSP0/CPU0:router-pe#show l2vpn xconnect pw-id 200 det

Group Transport, XC Transport, state is up; Interworking none
  Description: Transport
  AC: Bundle-Ether100.200, state is up
    Type VLAN; Num Ranges: 1
    VLAN ranges: [200, 200]
    MTU 9206; XC ID 0xa0000019; interworking none
    Statistics:
      packets: received 256535207083, sent 498000190258
      bytes: received 53258327407296, sent 643037489071235
      drops: illegal VLAN 0, illegal length 0
  PW: neighbor 10.1.200.2, PW ID 200, state is up ( established )
    PW class mpls, XC ID 0xc000000a
    Encapsulation MPLS, protocol LDP
    Source address 10.2.200.2
    PW type Ethernet, control word disabled, interworking none
    PW backup disable delay 0 sec
    Sequencing not set
    Load Balance Hashing: src-dst-ip

    PW Status TLV in use
      MPLS         Local                          Remote
      ------------ ------------------------------ -----------------------------
      Label        16000                          16000
      Group ID     0x1a0                          0x4000100
      Interface    Bundle-Ether100.200            TenGigE0/0/0/1.200
      MTU          9206                           9206
      Control word disabled                       disabled
      PW type      Ethernet                       Ethernet
      VCCV CV type 0x2                            0x2
                   (LSP ping verification)        (LSP ping verification)
      VCCV CC type 0x6                            0x6
                   (router alert label)           (router alert label)
                   (TTL expiry)                   (TTL expiry)
      ------------ ------------------------------ -----------------------------
    Incoming Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    Outgoing Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    MIB cpwVcIndex: 3221225482
    Create time: 28/03/2019 00:10:01 (20w0d ago)
    Last time status changed: 14/08/2019 23:02:09 (13:34:43 ago)
    Last time PW went down: 14/08/2019 23:02:09 (13:34:43 ago)
    Statistics:
      packets: received 498000190258, sent 256535207083
      bytes: received 643037489071235, sent 53258327407296

 

Thank you so much for your help.

 

9 REPLIES 9

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

Hello. It should work according to https://community.cisco.com/t5/service-providers-documents/asr9000-xr-load-balancing-architecture-and-characteristics/ta-p/3124809#case1.

But i noticed that you use dst-ip hash in bundle-ether. I think you should disable this setting and use default. Also you could exclude l4 info from hash by configuring 

cef load-balancing fields L3 global
Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

Hello Evgeniy. Thank you so much for the reply and sorry for having taken so long to respond.

Unfortunately excluding L4 info from hash calculation didn't do the trick. I also tried every configuration suggested in the link you provided, which I've had already looked into even before posting in the forum, but couldn't find a way to balance traffic.

I even configured a FAT PW between both ends of the L2VPN but it didn't work either:

 

l2vpn
 pw-class transporte_class
  encapsulation mpls
   control-word
   load-balancing
    flow-label both
   !
  !
 xconnect group Transporte
  p2p Transporte
   interface Bundle-Ether100.200
   neighbor ipv4 10.1.200.2 pw-id 200
    pw-class transporte-class
   !
  !
 !
!

I don't know, maybe the cause is that there aren't any L3 (sub)interfaces configured on the bundle-ether, so the hashing calculation can't be done.

 

So, I'm still trying to find the configuration and any information anyone has would be helpful.

 

Thank you.


@Evgeniy Prichinin wrote:

Hello. It should work according to https://community.cisco.com/t5/service-providers-documents/asr9000-xr-load-balancing-architecture-and-characteristics/ta-p/3124809#case1.

But i noticed that you use dst-ip hash in bundle-ether. I think you should disable this setting and use default. Also you could exclude l4 info from hash by configuring 

cef load-balancing fields L3 global

 

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

What kind of traffic flows into l2vpn?

 

fat label is used to load balancing mpls traffic in bundle-ethers between mpls routers, so it will not help.

Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

On both ends of the PW we have an AC which is allowing incoming L2 frames tagged with VLAN 200; traffic is then encapsulated into MPLS and sent through the L2VPN. Here´s the output of the lvpn xconnect status of the PW, taken from the customer-facing end of the L2VPN:

 

RP/0/RSP0/CPU0:RPE-01#sh l2vpn xconnect pw-id 200 det
Tue Sep  3 14:39:01.241 ART

Group Transporte, XC Transporte, state is up; Interworking none
  Description: Transporte
  AC: Bundle-Ether100.200, state is up
    Type VLAN; Num Ranges: 1
    VLAN ranges: [200, 200]
    MTU 9206; XC ID 0xa0000019; interworking none
    Statistics:
      packets: received 298210575515, sent 572150150837
      bytes: received 62781404682410, sent 736782573729841
      drops: illegal VLAN 0, illegal length 0
  PW: neighbor 10.1.200.2, PW ID 200, state is up ( established )
    PW class mpls, XC ID 0xc000000a
    Encapsulation MPLS, protocol LDP
    Source address 10.2.200.2
    PW type Ethernet, control word disabled, interworking none
    PW backup disable delay 0 sec
    Sequencing not set

    PW Status TLV in use
      MPLS         Local                          Remote
      ------------ ------------------------------ -----------------------------
      Label        16000                          16000
      Group ID     0x1a0                          0x4000100
      Interface    Bundle-Ether100.200            TenGigE0/0/0/1.200
      MTU          9206                           9206
      Control word disabled                       disabled
      PW type      Ethernet                       Ethernet
      VCCV CV type 0x2                            0x2
                   (LSP ping verification)        (LSP ping verification)
      VCCV CC type 0x6                            0x6
                   (router alert label)           (router alert label)
                   (TTL expiry)                   (TTL expiry)
      ------------ ------------------------------ -----------------------------
    Incoming Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    Outgoing Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    MIB cpwVcIndex: 3221225482
    Create time: 28/03/2019 00:10:01 (22w5d ago)
    Last time status changed: 27/08/2019 05:46:40 (1w0d ago)
    Last time PW went down: 27/08/2019 05:46:38 (1w0d ago)
    Statistics:
      packets: received 572150150837, sent 298210575515
      bytes: received 736782573729841, sent 62781404682410

Thank you so much for your help!

Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

Hello,

you have dst-ip hash algorithm configured under the bundle interface. Are you sure that there are multiple DST IPs on the CE site? Have you tried to configure src-ip hash? 

interface Bundle-Ether100
mtu 9216
bundle load-balancing hash dst-ip

What kind of router platform is it - NCS or A9K?

Best Regards,

P.

Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

Hello, filopeter.
I've also tried configuring src-ip hash but it didn't help either...
I'm not sure about the number of destination IPs in the CE because we don't have control over it; the CE is managed by our customer, we only provide a L2L service from PE to PE.
Lastly, the router platform we're using is ASR9K, ASR9001 with Typhoon based LC to be specific.

Thanks for your reply.

Best regards,
Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

Try to turn on the control-word under the pw-class on both PEs, so you will see it is enabled/negotiated. Please let me know the following output after this configuration "sh l2vpn xconnect pw-id 200 de".

Remove the "bundle load-balancing hash" command under the "interface Bundle-Ether100", so it will return to the default, which should be Src and Dst MAC based.

Under l2vpn configuration change the "load-balancing flow src-dst-ip" to "load-balancing flow src-dst-mac"

Best Regards,

P.

 

Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

I've tried turning on the control-word on both PEs and applied the other configurations you suggested but traffic is still not balanced. Here's the output of the status of the PW:

 

 

RP/0/RSP0/CPU0:RPE-01#sh l2vpn xconnect pw-id 200 det
Thu Sep  5 08:38:08.201 ART

Group Transporte, XC Transporte, state is up; Interworking none
  Description: Transporte
  AC: Bundle-Ether100.200, state is up
    Type VLAN; Num Ranges: 1
    VLAN ranges: [200, 200]
    MTU 9206; XC ID 0xa0000019; interworking none
    Statistics:
      packets: received 301548464958, sent 578043723749
      bytes: received 63527046452555, sent 744178739937323
      drops: illegal VLAN 0, illegal length 0
  PW: neighbor 10.1.200.2, PW ID 200, state is up ( established )
    PW class transporte_class, XC ID 0xc000000a
    Encapsulation MPLS, protocol LDP
    Source address 10.2.200.2
    PW type Ethernet, control word enabled, interworking none
    PW backup disable delay 0 sec
    Sequencing not set
    Load Balance Hashing: src-dst-mac

    PW Status TLV in use
      MPLS         Local                          Remote
      ------------ ------------------------------ -----------------------------
      Label        16000                          16000
      Group ID     0x1a0                          0x4000100
      Interface    Bundle-Ether100.200            TenGigE0/0/0/1.200
      MTU          9206                           9206
      Control word enabled                        enabled
      PW type      Ethernet                       Ethernet
      VCCV CV type 0x2                            0x2
                   (LSP ping verification)        (LSP ping verification)
      VCCV CC type 0x7                            0x7
                   (control word)                 (control word)
                   (router alert label)           (router alert label)
                   (TTL expiry)                   (TTL expiry)
      ------------ ------------------------------ -----------------------------
    Incoming Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    Outgoing Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    MIB cpwVcIndex: 3221225482
    Create time: 28/03/2019 00:10:01 (23w0d ago)
    Last time status changed: 05/09/2019 08:35:26 (00:00:42 ago)
    Last time PW went down: 05/09/2019 08:35:23 (00:00:46 ago)
    Statistics:
      packets: received 578043723749, sent 301548464958
      bytes: received 744178739937323, sent 63527046452555

 

 

I've also changed the "load-balancing flow src-dst-ip" to "load-balancing flow src-dst-mac" in both PEs and removed "bundle load-balancing hash" from interface Bundle-Ether100.

 

In case it helps, I share you the detail of the current load-balancing status:

 

RP/0/RSP0/CPU0:RPE-01#sh bundle load-balancing bundle-ether 100 detail location 0/0/cpu0
Thu Sep  5 09:01:23.411 ART

Bundle-Ether100
  Type:                  Ether (L3)
  Members <current/max>: 2/64
  Total Weighting:       2
  Load balance:          Default
  Locality threshold:    65
  Avoid rebalancing?     False
  Sub-interfaces:        1

  Member Information:
    Port:                 LON  ULID  BW
    --------------------  ---  ----  --
    Gi0/0/1/0               0     0   1
    Gi0/0/1/1               1     1   1

  Sub-interface Information:
    Sub-interface                 Type  Load Balance  Locality
                                        Hash          Threshold
    ----------------------------  ----  ------------  ---------
    Bundle-Ether100.200           L2    Default              65

  Platform Information:
  =====================

                  * Bundle Summary Information *
                    --------------------------

Interface              : Bundle-Ether100       Ifhandle           : 0x000001a0
Lag ID                 : 3                     Virtual Port       : 255
Number of Members      : 2                     Local to LC        : Yes
Hash Modulo Index      : 2
MGSCP Operational Mode : No

Member Information:
LON        Interface       ifhandle     SFP   port   slot remote/rack_id
-----   ---------------   ----------    ---   ----   ---- --------------
0       Gi0/0/1/0         0x040002c0     96     16      2       0/0
1       Gi0/0/1/1         0x04000300     99     17      2       0/0

Preroute Member Information:
LON        Interface       ifhandle     SFP   port   slot remote/rack_id
-----   ---------------   ----------    ---   ----   ---- --------------
1       Gi0/0/1/1         0x04000300     99     17      2       0/0

                   * Bundle Table Information *
                     ------------------------

[NP 0]:
----------------------------------------------------------------------
    Unicast (Global) LAG table     |     Unicast  (Rack) LAG table
----------------------------------------------------------------------
 idx  local    VQI   port   VQI-LB | idx  local   VQI   port   VQI-LB
----------------------------------------------------------------------
  1      0     96     16      0       1      0     96     16      0
  2      0     99     17      0       2      0     99     17      0

[NP 1]:
-------------------------------------------------------------------------------------------------------------
    Unicast (Global) LAG table     |    Multicast (Local) LAG table    |    Unicast (Rack) LAG table
-------------------------------------------------------------------------------------------------------------
 idx  local    VQI   port   VQI-LB | idx  local    VQI   port   VQI-LB | idx  local    VQI   port   VQI-LB
-------------------------------------------------------------------------------------------------------------
   1      1     96     16      0       1      1     96     16      0       1      1     96     16      0
   2      1     99     17      0       2      1     99     17      0       2      1     99     17      0

                   * SW LAG Table Information *
                     ------------------------

--------------------------------------------------------------------------------------
          Global/Rack  LAG table          |             Local LAG table
--------------------------------------------------------------------------------------
 idx  local    LON    VQI   port   VQI-LB | idx  local    LON    VQI   port   VQI-LB
--------------------------------------------------------------------------------------
   1      1      0     96     16      0     1      1      0     96     16      0
   2      1      1     99     17      0     2      1      1     99     17      0

===============================================================================

And here's the output of the "monitor interfaces" command from the customer-facing PE. Note how the traffic is correctly balanced on the inbound direction but not on the outbound:

 

 

Protocol:General
Interface             In(bps)      Out(bps)     InBytes/Delta  OutBytes/Delta
BE100.200            (statistics not available)
BE100                 54.5M/  2%   396.4M/ 19%    63.5T/13.2M    744.2T/100.3M
Gi0/0/1/0             27.1M/  2%   396.4M/ 39%    31.7T/6.6M     739.6T/103.5M
Gi0/0/1/1             27.2M/  2%        0/  0%    31.7T/6.5M       4.6T/226

Please, let me know if there's anything else that comes to your mind.

 

Thank you so much for your time.

 

Best regards,

 

Beginner

Re: L2 Bundle interface load-balancing problem on Cisco ASR9K

Hi Renzo,

I have checked the available documentation, bud did not find any other way how to configure it.

You may try to configure the following command to adjust the hash algorithm in the global configuration mode:

cef load-balancing algorithm adjust

before opening a TAC case.

Best Regards,

P.

 

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