7200 VXR ATM PVC bonding VC's together

Answered Question
Oct 13th, 2009
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Hi,


I'm trying to configure the following scheme :


[LAN]--[CPE]-------<ATM 7200 ETH>----

                       |

[LAN]--[CPE]-----


The 2 ATM PVC's (16/2055 and 16/2056) should be bonded together to get a

fully transparent L2 link without any routing involved.


I browsed through the Cisco documentation, especially the "Layer 2 local

switching" document at

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/fslocal.html

which says it's possible with the following config :


----

interface atm1/0

pvc 16/2055 l2transport

encapsulation aal5

pvc 16/2056 l2transport

encapsulation aal5


connect randomname atm1/0 16/2055 atm1/0 16/2056

-----


The last command gives me the following error :


CONN: cannot connect two endpoints on the same interface

%CONN: Invalid Command


But the manual says :


"Starting with Cisco IOS Release 12.0(30)S, you can configure same-port

switching following the steps in this section. "



Can anybody tell me how to get this working? Is this a Cisco bug?

I'm running c7200p-advipservicesk9-mz.124-15.T1.bin on this box.


My hardware is :


Cisco 7206-VXR with PA-A3-OC3 for ATM connectivity and an NPE-G2 as a

processing engine.


Regards,


Remco Bressers

Signet B.V.

Correct Answer by Giuseppe Larosa about 7 years 5 months ago

Hello Remco,

the configuration looks like correct.


I post a pdf of troubleshooting ATM bridged PVCs


and links


http://www.cisco.com/en/US/tech/tk39/tk48/technologies_configuration_example09186a008009455f.shtml


And Q & A


http://www.cisco.com/en/US/tech/tk39/tk371/technologies_q_and_a_item09186a00800fb730.shtml#qa5



Also there is routed bridged encapsulation that could be an alternate way to do this.


I tested this several years ago and if I remember correctly it worked for me.


check also what the devices at the other end of PVCs expect in terms of ATM encapsulation and if they are using RFC 1483 bridged mode (that is they place an ethernet frame carrying an IP packet inside an ATM PDU).


the possible trick could be that of using a LAN interface to be placed in same briding group with the role of handling ethernet frames.

But this should be useful only if you want to route the IP packets.


Hope to help

Giuseppe




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Giuseppe Larosa Wed, 10/14/2009 - 00:05
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Hello Remco,

IOS releases numbering is more complex.


12.0S is a train for service provider that is still alive and used on high end routers.


you have 12.4(15)T1 and you would expect to be able to local switch on the same port.

Unfortunately, this is not the case.


changing IOS image could be considered but it requires care you may have some feature running that is not supported in 12.0S train.


I would try to use transparent bridging that is:

to create two point-to-point subinterfaces and to bridge between them


int atm1/0.2055 point-to-point

pvc 16/2055

enc aal5snap

!

no ip address

bridge-group 1


int atm1/0.2056 point-to-point

pvc 16/2056

enc aal5snap

!

no ip address

bridge-group 1

!



bridge 1 protocol ieee


Hope to help

Giuseppe


signet Wed, 10/14/2009 - 00:08
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Hi Giuseppe,


Thanks for the reply! Does your solution work with my current configuration for other PVC's on PPPoA? I don't want to break things.


Especially the "bridge 1 protocol ieee" on the global level. This doesn't have any influence over other interfaces right?

Giuseppe Larosa Wed, 10/14/2009 - 00:48
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Hello Remco,

you should be able to use PPPoA on other ATM subinterfaces


>> Especially the "bridge 1 protocol ieee" on the global level. This doesn't have any influence over other interfaces right?


this applies only to interfaces members of this bridge-group and defines what type of STP is spoken.


Hope to help

Giuseppe


signet Wed, 10/14/2009 - 00:51
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Great! I'll try this out on the lab overhere. If it's ok i can implement this on the live platform.


Thanks a million!

signet Thu, 10/15/2009 - 00:20
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Hi Giuseppe,


I tried out the configuration, but it doesn't seem to work :(.


The configuration on the 7200 :


-----


interface ATM1/0.162055 point-to-point

no ip redirects

no ip proxy-arp

no snmp trap link-status

bridge-group 10

pvc 16/2055

vbr-nrt 512 512

encapsulation aal5snap

!

!

interface ATM1/0.162056 point-to-point

no ip redirects

no ip proxy-arp

no snmp trap link-status

bridge-group 10

pvc 16/2056

vbr-nrt 512 512

encapsulation aal5snap

!

bridge 10 protocol ieee


-----


Have you got any tips for me?


Regards,


Remco

Correct Answer
Giuseppe Larosa Thu, 10/15/2009 - 00:53
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Hello Remco,

the configuration looks like correct.


I post a pdf of troubleshooting ATM bridged PVCs


and links


http://www.cisco.com/en/US/tech/tk39/tk48/technologies_configuration_example09186a008009455f.shtml


And Q & A


http://www.cisco.com/en/US/tech/tk39/tk371/technologies_q_and_a_item09186a00800fb730.shtml#qa5



Also there is routed bridged encapsulation that could be an alternate way to do this.


I tested this several years ago and if I remember correctly it worked for me.


check also what the devices at the other end of PVCs expect in terms of ATM encapsulation and if they are using RFC 1483 bridged mode (that is they place an ethernet frame carrying an IP packet inside an ATM PDU).


the possible trick could be that of using a LAN interface to be placed in same briding group with the role of handling ethernet frames.

But this should be useful only if you want to route the IP packets.


Hope to help

Giuseppe




Attachment: 
signet Thu, 10/15/2009 - 01:28
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Thanks again!


Personally i was thinking about me not configuring "bridge irb" on the box. This should be enabled right?


Is this command 'safe' to enter e.g. will it interfere my running interfaces (routing, switching). ?


Thanks!

hadi.tannous Wed, 09/22/2010 - 06:33
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Hi Giuslar,


I am using a different IOS and getting the same error



Router(config)#do sho ver | in .bin
System image file is "disk0:c7301-adventerprisek9-mz.122-33.SRD4.bin"


Router(config)#do sho run int atm1/0 
Building configuration...

Current configuration : 220 bytes
!
interface ATM1/0
no ip address

no atm enable-ilmi-trap
pvc 1/100 l2transport
  encapsulation aal5
!
pvc 1/200 l2transport
  encapsulation aal5
!
pvc 2/100 l2transport
  encapsulation aal5
!
end

Router(config)#connect test atm 1/0 1/100 atM 1/0 2/100
CONN: cannot connect two endpoints on the same interface
%CONN: Invalid Command
Router(config)#connect test atm 1/0 1/100 atM 1/0 1/100
CONN: cannot connect two endpoints on the same interface
%CONN: Invalid Command
Router(config)#connect test atm 1/0 1/100 atM 1/0 1/200
CONN: cannot connect two endpoints on the same interface
%CONN: Invalid Command
Router(config)#do sho ver | in .bin
System image file is "disk0:c7301-adventerprisek9-mz.122-33.SRD4.bin"




Thx,

Hadi


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