Solved: Point to Point L2VPN in IOS XR

darshakpp · ‎06-19-2013

Hi,

Im working out p2p L2vpn between ASR9K and IOS platforms (7600). PE-CE connectivity is using vlan encapsulation at both ends. Default PW type negotiated is ethernet (VC type 5) and VC comes up. But CE to CE communication is not happening. I changed the interworking mode to IP at both ends and it started working.

What is the difference between these PW types. Has anyone come across the same problem? I believe it should work with Ethernet type itself.

Below are the output details before and after changing PW types.

Default PW-type:

Group ASR-G2, XC A-G2, state is up; Interworking none

AC: GigabitEthernet0/0/0/1.607, state is up

Type VLAN; Num Ranges: 1

VLAN ranges: [607, 607]

MTU 1546; XC ID 0x840004; interworking none

Statistics:

packets: received 1045, sent 25782

bytes: received 123094, sent 1706886

drops: illegal VLAN 0, illegal length 0

PW: neighbor 10.20.0.3, PW ID 107, state is up ( established )

PW class not set, XC ID 0xc0000004

Encapsulation MPLS, protocol LDP

Source address 124.7.227.20

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 16022 45285

Group ID 0x4000100 0x0

Interface GigabitEthernet0/0/0/1.607 unknown

MTU 1546 1546

Control word disabled disabled

PW type Ethernet Ethernet

VCCV CV type 0x2 0x2

(LSP ping verification) (LSP ping verification)

VCCV CC type 0x6 0x2

(router alert label) (router alert label)

(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: 3221225476

Create time: 19/06/2013 16:23:08 (00:02:30 ago)

Last time status changed: 19/06/2013 16:25:28 (00:00:10 ago

Interworking IPv4:

Group ASR-G2, XC A-G2, state is up; Interworking IPv4

AC: GigabitEthernet0/0/0/1.607, state is up

Type VLAN; Num Ranges: 1

VLAN ranges: [607, 607]

MTU 1546; XC ID 0x840004; interworking IPv4

Statistics:

packets: received 1045, sent 25780

bytes: received 123094, sent 1706750

drops: illegal VLAN 0, illegal length 0

PW: neighbor 10.20.0.3, PW ID 107, state is up ( established )

PW class not set, XC ID 0xc0000004

Encapsulation MPLS, protocol LDP

Source address 124.7.227.20

PW type IP, control word disabled, interworking IPv4

PW backup disable delay 0 sec

Sequencing not set

PW Status TLV in use

MPLS Local Remote

------------ ------------------------------ -----------------------------

Label 16022 45280

Group ID 0x4000100 0x0

Interface GigabitEthernet0/0/0/1.607 unknown

MTU 1546 1546

Control word disabled disabled

PW type IP IP

VCCV CV type 0x2 0x2

(LSP ping verification) (LSP ping verification)

VCCV CC type 0x6 0x2

(router alert label) (router alert label)

(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: 3221225476

Create time: 19/06/2013 14:16:02 (02:04:47 ago)

Last time status changed: 19/06/2013 15:18:07 (01:02:41 ago)

Statistics:

packets: received 25780, sent 1045

bytes: received 1706750, sent 123094

Appreciate your help!

Regards,

Darshak

Evan Roggenkamp · ‎04-04-2014

sorry. necro posting. cisco page loading slow today.

View solution in original post

Samil Lama · ‎06-19-2013

Hi,

I recommend you to create PW Classes:

7600 Series
Router(config)#pseudowire-class TEST
Router(config-pw-class)#encapsulation mpls
Router(config-pw-class)#interworking ?
  ethernet  Ethernet interworking
  ip        IP interworking
  vlan      VLAN interworking
Router(config-pw-class)#internetworking ethernet
And call above in the interface
  
Router(config-if)# xconnect    pw-class TEST

ASR9k Series RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# l2vpn
RP/0/RSP0/CPU0:router(config-l2vpn)# pw-class TEST
RP/0/RSP0/CPU0:router(config-l2vpn-pwc)# encapsulation mpls
RP/0/RSP0/CPU0:router(config-l2vpn-pwc-encap-mpls)# transport-mode ethernet
RP/0/RSP0/CPU0:router(config-l2vpn-pwc-encap-mpls)# exit
RP/0/RSP0/CPU0:router(config-l2vpn-pwc-encap)# exit
RP/0/RSP0/CPU0:router(config-l2vpn-pwc)# exit
RP/0/RSP0/CPU0:router(config-l2vpn)# xconnect group TESTGROUP
RP/0/RSP0/CPU0:router(config-l2vpn-xc)# p2p TESTP2P
RP/0/RSP0/CPU0:router(config-l2vpn-xc-p2p)# neighbor  pw-id 
RP/0/RSP0/CPU0:router(config-l2vpn-xc-p2p-pw)# pw-class TEST
RP/0/RSP0/CPU0:router(config-l2vpn-xc-p2p-pw)# exit
RP/0/RSP0/CPU0:router(config-l2vpn-xc-p2p)# interface TenGigE0/0/0/0.40 //Example

Recommended:

L2VPN on ASR9k

http://www.cisco.com/en/US/docs/routers/asr9000/software/asr9k_r4.1/lxvpn/command/reference/b_lxvpn_cr41asr9k_chapter_010.html#wp3681643325

Regards.

Please don't forget to rate helpful posts.

darshakpp · ‎06-19-2013

Hello Samil,

Thanks for the response.

As I mentioned earlier, VC stays up in all the cases. I tried VCtype 5 (Ethernet) and VCtype4 (Ethernet Vlan). I beleive it should be VC type 4, since im using vlan encapsulation on both attachmet circuits. But there is no communication between CE's.

It starts working after configuring Interworking IP on both ends, which removes the layer2 header while sending the payload across the pseudowire.

Regards,

Darshak

darshakpp · ‎06-26-2013

Hello everyone,

I got this solved. I applied " rewrite ingress tag pop..." command on the AC interface. Below is the working configuration.

XR Config:

interface GigabitEthernet0/0/0/1.900609 l2transport

encapsulation dot1q 900 second-dot1q 609

rewrite ingress tag pop 2 symmetric

mtu 1522

l2vpn

pw-class MPLS

encapsulation mpls

transport-mode vlan

xconnect group ASR-J2

p2p ASR-J2

interface GigabitEthernet0/0/0/1.900609

neighbor 10.10.10.255 pw-id 109

pw-class MPLS

IOS Config:

interface G0/1.609

xconnect 124.7.227.20 109 encapsulation mpls

What I observed is the difference in the L2 header size calculation. Without the "rewrite" command, XR is calculating L2 header size as 14 bytes without taking the double tag (extra 8 bytes) in consideration. So to get the payload size as 1500 bytes, i applied 1514 bytes on the interface. This matched with the remote end device MTU 1500. But there is no communication between CE.

After applying "rewrite ingress tag pop2 symmetric" command, it does consider the extra bytes as well. I had to set the MTU as 1522 to get the payload size as 1500. Now the CE is able to commmunicate with each other. I tested with IOS and JUNOS on the remote end, the behavior remains the same.

"rewrite ingress tag pop2 symmetric" removes the vlan tags (both outer and inner) while sending the packet across MPLS pseudowire and add both tags back while sending to Attachment circuit.

So here are my questions ,

why XR is not considering vlan tags for L2 header size calculation
How does this behavior change when "rewrite.." command is applied

Appreciate your response.

Regards,

Darshak

skondala · ‎06-28-2013

because IOS pops the tage by default and XR does not.

on XR interface.. you have 2 dot1Q tags so with rewrite POP 2 symmetric

encapsulation dot1q 900 second-dot1q 609

rewrite ingress tag pop 2 symmetric

you are removing tags when sending to Core and adding them back when going towards AC side

Reagrds, Satish.

darshakpp · ‎06-28-2013

Thanks Satish,

"because IOS pops the tage by default and XR does not. "

So the Packets are carried through the MPLS pseudowire with native ethernet header (14 bytes SA + DA + Ethertype). Vlan Tags will be stripped out.

Regards,

Darshak

skondala · ‎07-01-2013

Thats correct...the core wont have any dot1q tags

Reagrds, Satish.

sezaar · ‎12-25-2017

Hello ALL,

by any chance does any one have this configuration working between Junos and Cisco 7600 with the double tag

maritpra · ‎03-26-2014

Sorry replied on wrong place.

Evan Roggenkamp · ‎04-04-2014

sorry. necro posting. cisco page loading slow today.