CDP ASR920 IOS-XE Issue

[chefwearer]

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

[Vinit Jain]

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

[chefwearer]

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#

[Vinit Jain]

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

[chefwearer]

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#

[Vinit Jain]

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. 

[chefwearer]

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. 

[Vinit Jain · Accepted solution]

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

[chefwearer]

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#

[Vinit Jain]

Could you please share the config that you used.

[chefwearer]

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

[Vinit Jain]

Thanks,

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

Regards

Vinit

[Vinit Jain]

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.

[tachavez]

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