Re: ATOMoGRE unidirectional forwarding (7609-RSP720-ES+ card)

Octavio Alfageme · ‎04-05-2013

Dear all,

I would be grateful if somebody could give me any idea about the behavior I have in my network. I have configured ATOMoGRE between two 7609s in the following way.

* GRE tunnel endpoints are:

a. ROUTER1: 7609 RSP720 (IOS 15.2(4)S1) GE interface in a ES+ card (router running in PFC3BXL mode, as it has a SIP600 card equipped)

b. ROUTER2: 7609 RSP720 (IOS 15.2(4)S1) POS interfaces in a SIP400 (router running in PFC3CXL mode)

* MPLS-TE engineering is enabled in the GRE tunnel and RSVP signalled LSP inside the tunnel is up and running. I use affinity-bits to set the LSP's path.

* Pseudowire between two EVCs in ports of ES+ cards is created and it seems to be properly signalled by T-LDP

Traffic is sent in the VC from a CE connected to ROUTER1 and received by a CE connected to ROUTER2 (remote CE's ARP entry is completed in ROUTER2). However, traffic sent from ROUTER2's CE inside the VC is not received by ROUTER1's CE. This traffic is accounted as sent by the ROUTER2's VC endpoint. We can see it in the VC statistics:

ROUTER1#show mpls l2transport vc 1000 detail

Local interface: Gi8/3 up, line protocol up, Ethernet:10 up

Destination address: 10.10.10.2, VC ID: 1000, VC status: up

Output interface: Tu103, imposed label stack {24}

Preferred path: Tunnel103, active

Default path:

Next hop: point2point

Create time: 1d09h, last status change time: 1d09h

Last label FSM state change time: 1d09h

Signaling protocol: LDP, peer 10.10.10.2:0 up

Targeted Hello: 10.10.10.1(LDP Id) -> 10.10.10.2, LDP is UP

Status TLV support (local/remote) : enabled/supported

LDP route watch : enabled

Label/status state machine : established, LruRru

Last local dataplane status rcvd: No fault

Last BFD dataplane status rcvd: Not sent

Last BFD peer monitor status rcvd: No fault

Last local AC circuit status rcvd: No fault

Last local AC circuit status sent: No fault

Last local PW i/f circ status rcvd: No fault

Last local LDP TLV status sent: No fault

Last remote LDP TLV status rcvd: No fault

Last remote LDP ADJ status rcvd: No fault

MPLS VC labels: local 31, remote 24

Group ID: local 0, remote 0

MTU: local 1500, remote 1500

Remote interface description:

Sequencing: receive disabled, send disabled

Control Word: On (configured: autosense)

SSO Descriptor: 10.10.10.2/1000, local label: 31

Dataplane:

SSM segment/switch IDs: 7302/15493 (used), PWID: 16

VC statistics:

transit packet totals: receive 0, send 25 <----- no packets received in ROUTER1

transit byte totals: receive 0, send 1700

transit packet drops: receive 0, seq error 0, send 0

ROUTER2#show mpls l2transport vc 1000 det

Local interface: Gi8/2 up, line protocol up, Ethernet:10 up

Destination address: 10.10.10.1, VC ID: 1000, VC status: up

Output interface: Tu103, imposed label stack {31}

Preferred path: Tunnel103, active

Default path:

Next hop: point2point

Create time: 1d22h, last status change time: 1d09h

Last label FSM state change time: 1d09h

Signaling protocol: LDP, peer 10.10.10.1:0 up

Targeted Hello: 10.10.10.2(LDP Id) -> 10.10.10.1, LDP is UP

Status TLV support (local/remote) : enabled/supported

LDP route watch : enabled

Label/status state machine : established, LruRru

Last local dataplane status rcvd: No fault

Last BFD dataplane status rcvd: Not sent

Last BFD peer monitor status rcvd: No fault

Last local AC circuit status rcvd: No fault

Last local AC circuit status sent: No fault

Last local PW i/f circ status rcvd: No fault

Last local LDP TLV status sent: No fault

Last remote LDP TLV status rcvd: No fault

Last remote LDP ADJ status rcvd: No fault

MPLS VC labels: local 24, remote 31

Group ID: local 0, remote 0

MTU: local 1500, remote 1500

Remote interface description:

Sequencing: receive disabled, send disabled

Control Word: On (configured: autosense)

SSO Descriptor: 10.10.10.1/1000, local label: 24

Dataplane:

SSM segment/switch IDs: 23454/11162 (used), PWID: 15

VC statistics:

transit packet totals: receive 65, send 96 <---- ROUTER2's endpoint seems to have bidirectional connectity

transit byte totals: receive 3900, send 7878

transit packet drops: receive 0, seq error 0, send 0

* "mls mpls tunnel-recir" is enabled in both routers.

* It's not a MTU problem, as I'm testing the connectivity with small pings from the CEs.

* Might there be a support problem of ATOMoGRE in PFC3BXL mode (ROUTER1)?

Any idea will be welcomed, as I don't understand this behaviour.

Thank you in advance

Octavio

Andre Gustavo Albuquerque · ‎04-06-2013

I am not sure whether this particular use case is supported or not...
Would L2TPv3 be an option for you?
If so, you could use it as the transport tunnel instead of mpls/gre.
See more info at http://www.cisco.com/en/US/docs/routers/7600/install_config/ES40_config_guide/es40_chap4.html#wp1731928

Cheers

Sent from Cisco Technical Support iPad App

Octavio Alfageme · ‎04-07-2013

Thank you very much, Andre.

L2TPv3 wouldn't be my first option (I also use the GRE tunnel for native IP traffic), but I tested it following the instructions you sent and I can confirm that it works fine, so I suppose it would be my choice for layer 2.

In any case, I will go on with my ATOMoGRE tests (changing tunnel source to loopback interfaces, configuring tunnels as unnumbered, ...), as I would like to find an explanation for the odd behaviour I see. In case I get any result I will report it within this thread.

Thanks a lot for your help

Regards

Octavio