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Beginner

CDP ASR920 IOS-XE Issue

Anyone get CDP working both ways on a ASR920/IOS XE? Here's what I'm seeing:

 

If I enable CDP globally with "CDP run" on the 920, from an IOS neighbor, I can see the 920 via CDP. Although, I cannot see the IOS neighbor from the 920.

 

I've tried doing "CDP enable" on the 920 interface facing the IOS neighbor, but no luck. 

 

I'm running a ASR-920-12CZ-A on IOS-XE version 03.14.01.S

1 ACCEPTED SOLUTION

Accepted Solutions
Highlighted

service instance 1 ethernet
  description Native VLAN for untagged packets
  encapsulation untagged
  l2protocol peer cdp
  bridge-domain 4094
 !

Can you configure a different vlan other than vlan 1 (ex. 4094) as the native then configure a service instance as shown above and see if that helps.

On the ME3400, you can configure switchport trunk native vlan 4094.

Sorry to ask you to try different things. I would have tried that in my lab but i dont have the setup with ME-3400.

Please let me know if this works

Regards

Vinit

Thanks
--Vinit

View solution in original post

13 REPLIES 13
Highlighted
Cisco Employee

Could you please share the configuration of the interface on ASR920. Is there any service-instance configured on the interface?

 

Thanks
--Vinit
Highlighted

Yes, see below:

 

interface GigabitEthernet0/0/4
 description **To LAB 3400 G0/5 REP 1**
 mtu 9216
 no ip address
 load-interval 30
 media-type auto-select
 negotiation auto
 rep segment 1
 storm-control broadcast level 1.00
 storm-control multicast level 1.00
 storm-control action trap
 cdp enable
 source template sloam
 ethernet oam remote-loopback supported
 ethernet oam
 service instance trunk 1 ethernet
  encapsulation dot1q 1,99,3001-3002
  rewrite ingress tag pop 1 symmetric
  bridge-domain from-encapsulation
 !
!

 

I took a packet dump of the CDP packets going back and fourth and found the CDP packets coming from the 3400 are tagged with VLAN 1, while the CDP packets from the ASR920 are untagged.

 

I also found the 3400 is sending and receiving CDP packets OK, but the ASR920 is not. See output of "show cdp traff"

LAB_920#sh cdp traffic
CDP counters :
        Total packets output: 291967, Input: 0
        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
        No memory: 0, Invalid packet: 0,
        CDP version 1 advertisements output: 0, Input: 0
        CDP version 2 advertisements output: 291967, Input: 0
LAB_920#

 

 

Highlighted

Can you configure l2protocol forward cdp under the physical as well as service instance.

i think this configuration is required to get this working:

http://www.cisco.com/c/en/us/td/docs/routers/asr920/configuration/guide/ce/b_ce_xe-313s-asr920-book/b_ce_xe-313s-asr920-book_chapter_01.html

Hope this helps.

Regards

Vinit

Thanks
--Vinit
Highlighted

I don't have the option to do "l2protocol forward cdp" outside of the service instance. I've added it to the service instance but am still not receiving any CDP frames.

 

interface GigabitEthernet0/0/4
 description **To GPON LAB 3400 G0/5 REP 1**
 mtu 9216
 no ip address
 load-interval 30
 media-type auto-select
 negotiation auto
 rep segment 1
 storm-control broadcast level 1.00
 storm-control multicast level 1.00
 storm-control action trap
 cdp enable
 source template sloam
 ethernet oam remote-loopback supported
 ethernet oam
 service instance trunk 1 ethernet
  encapsulation dot1q 1,99,3001-3002
  rewrite ingress tag pop 1 symmetric
  l2protocol forward cdp
  bridge-domain from-encapsulation
 !
end

 

CDP counters :
        Total packets output: 292635, Input: 0
        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
        No memory: 0, Invalid packet: 0,
        CDP version 1 advertisements output: 0, Input: 0
        CDP version 2 advertisements output: 292635, Input: 0
LAB_920#

 

Highlighted

is there a different vlan acting as native vlan other than vlan 1. i have seen issues with the native vlan being different.

Also, can you try "l2protocol peer cdp" config as well under service instance. 

 

Thanks
--Vinit
Highlighted

Switching to "l2protocol peer cdp" made no difference.

Looking into how to adjust/specify native VLAN now. The attached packet dump shows the CDP packets from the 3400 have VLAN 1 specified as the native, while the native VLAN is omitted from the 920 CDP packets. 

Highlighted

service instance 1 ethernet
  description Native VLAN for untagged packets
  encapsulation untagged
  l2protocol peer cdp
  bridge-domain 4094
 !

Can you configure a different vlan other than vlan 1 (ex. 4094) as the native then configure a service instance as shown above and see if that helps.

On the ME3400, you can configure switchport trunk native vlan 4094.

Sorry to ask you to try different things. I would have tried that in my lab but i dont have the setup with ME-3400.

Please let me know if this works

Regards

Vinit

Thanks
--Vinit

View solution in original post

Highlighted

Success, sort of. I setup the 920 to use VLAN 4094 as native, but that didn't work. Using VLAN 1 as the native VLAN worked. But I need this to work on trunk ports; this appears to be like an access port. Is there a way to get this to work on trunk ports? 

 

LAB_920#sh cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
                  D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
GPON_LAB_1       Gig 0/0/4         179              S I   ME-3400EG Gig 0/5

Total cdp entries displayed : 1


LAB_920#sh cdp traff
LAB_920#sh cdp traffic
CDP counters :
        Total packets output: 293993, Input: 86
        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
        No memory: 0, Invalid packet: 0,
        CDP version 1 advertisements output: 0, Input: 0
        CDP version 2 advertisements output: 293993, Input: 86
LAB_920#

Highlighted

Could you please share the config that you used.

Thanks
--Vinit
Highlighted

Yep, sure, Vinit. The following config appears to have solved my problem. Thanks so much for sharing your expertise!

 

interface GigabitEthernet0/0/4


 service instance 1 ethernet
  encapsulation untagged
  l2protocol peer cdp
  bridge-domain 1
 !
 service instance trunk 2 ethernet
  encapsulation dot1q 99,3001-3002
  rewrite ingress tag pop 1 symmetric
  bridge-domain from-encapsulation
 !
end

 

Highlighted

Thanks,

Please mark the question as answered if your query has been resolved.

Regards

Vinit

Thanks
--Vinit
Highlighted

the workaround that i suggested should help. configuring another vlan as native but creating another service instance. 

Please let me know if that config works.

Thanks
--Vinit
Highlighted

Hi Vinit, which ios version allowes you to configure the encapsulation parameter within the service instance? I have tried several ios version and in every single one there is no encapsulation hence l2 forwarding is not enabled. I used a ME-3400EG-2CS-A with 

me340x-metroaccessk9-mz.122-54.SE

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