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What platform are you on? I ran into numerous issues with XR + BFD on NCS5501-SE hardware; worked with TAC and confirmed. It's broken for bundle interfaces (gives an error, won't take the config), broken for BGP (takes the config without error but doesn't work), and broken if VRRP is in use. It will only work on a single physical link on that platform. We swapped out for Arista 7280's ultimately.



?On 6/28/19, 1:19 PM, "cisco-nsp on behalf of christoffer@netravnen.de" <cisco-nsp-bounces@puck.nether.net on behalf of christoffer@netravnen.de> wrote:

c-nsp,

Anyone having tried running (BGP) BFD on XR in vrf on sub-interface of
bundle-ether interface with success? Have tried looking through
documentation at Cisco.com with no luck so far.

Currently trying to get a session up with an non-cisco device on the
other end. No avail. Luck is close to up.
Have tried reading the Cisco Documentation from 4.2 release concerning
the restrictions to BFD mentioned. But I cannot get around to be wiser
if the restrictions applies to the below mentioned situation or not. :???:



[.Cisco XR <=> Cisco SW (L2) <=> Juniper SW (L2) <=> Arista SW (L3)]
[ \ / \ / \ / ]
[ trunk trunk trunk trunk access access ]
[ \ / \ / \ / ]
[ #Vlan tagged# #Vlan tagged# #untagged# ]

BFD is tried configured between XR and Arista SW.

* Cisco XR <=> Cisco SW (L2) : trunk interface (LAG group)
* Cisco SW (L2) <=> Juniper SW (L2) : trunk interface
* Juniper SW (L2) <=> Arista SW (L3) : access interface

§ same Vlan tag is carried on traffic between Cisco XR <=> Juniper SW.
Juniper SW pops vlan tag before forwarding traffic to Arista SW.

Using "monitor traffic interface(...)matching "udp && (port 49152 ||
port 3784)" looking for traversing BFD packets on Juniper SW (L2)...
Returns an empty output. No packet(s) matched.



Configuration Example Snippet from XR:

bfd
interface Bundle-Ether500.600
no echo
!
!
interface Bundle-Ether500.600
vrf RED
ipv4 mtu 1500
ipv4 address 10.10.10.9 255.255.255.252
encapsulation dot1q 600
!
router bgp 65000
vrf RED
neighbor 10.10.10.10
remote-as 65001
bfd fast-detect
bfd multiplier 3
bfd minimum-interval 3000
!
!
!
interface Bundle-Ether500
mtu 9000
bundle minimum-active links 1
!
interface Te0/0/0/0
bundle id 500 mode active
!
interface Te0/0/1/3
bundle id 500 mode active
!


RP/0/RSP1/CPU0:XR#sh conf run int Bundle-Ether500.600
I/f: Bundle-Ether500.600, Location: 0/RSP1/CPU0
Dest: 10.10.10.10
Src: 10.10.10.9
State: DOWN for 0d:1h:0m:0s, number of times UP: 0
Session type: SW/V4/SH/BL
Received parameters:
Version: 0, desired tx interval: 0 ms, required rx interval: 0 ms
Required echo rx interval: 0 ms, multiplier: 0, diag: None
My discr: 0, your discr: 0, H/D/F/P/C/A: 0/0/0/0/0/0
Transmitted parameters:
Version: 0, desired tx interval: 0 ms, required rx interval: 0 ms
Required echo rx interval: 0 ms, multiplier: 0, diag: None
My discr: 0, your discr: 0, H/D/F/P/C/A: 0/0/0/0/0/0
Timer Values:
Local negotiated async tx interval: 0 ms
Remote negotiated async tx interval: 0 s
Desired echo tx interval: 0 s, local negotiated echo tx interval: 0 ms
Echo detection time: 0 ms, async detection time: 0 ms
Label:
Internal label: 289033/0x46909
Local Stats:
Intervals between async packets:
Tx: Number of intervals=0, min=0 s, max=0 s, avg=0 s
Last packet transmitted 0 s ago
Rx: Number of intervals=0, min=0 s, max=0 s, avg=0 s
Last packet received 0 s ago
Intervals between echo packets:
Tx: Number of intervals=0, min=0 s, max=0 s, avg=0 s
Last packet transmitted 0 s ago
Rx: Number of intervals=0, min=0 s, max=0 s, avg=0 s
Last packet received 0 s ago
Latency of echo packets (time between tx and rx):
Number of packets: 0, min=0 ms, max=0 ms, avg=0 ms
MP download state: BFD_MP_DOWNLOAD_NO_LC
State change time: Jun 28 14:14:14.147
Session owner information:
Desired Adjusted
Client Interval Multiplier Interval Multiplier
-------------------- --------------------- ---------------------
bgp-default 3 s 3 3 s 3


RP/0/RSP1/CPU0:XR#sh ver | i Cisco IOS XR Software
Cisco IOS XR Software, Version 5.3.4[Default]


RP/0/RSP1/CPU0:XR#show bfd counters packet
---empty_output---
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On 29/06/2019 05:13, David Hubbard wrote:
> What platform are you on?

ASR9k

> ran into numerous issues with XR + BFD on NCS5501-SE hardware; worked
> with TAC and confirmed. It's broken for bundle interfaces (gives an
> error, won't take the config), broken for BGP (takes the config
> without error but doesn't work), and broken if VRRP is in use. It
> will only work on a single physical link on that platform. We
> swapped out for Arista 7280's ultimately.

Got an off-list hint on what to do. Which got me going again.

BFD_MP_DOWNLOAD_NO_LC <-- Meant I forgot to turn on BFD for the
linecard.

Configured "bfd multipath include location ?/?/CPU?" did it.


Realised upon receiving hint. I had overlooked a section in the Cisco
configuration guide. Mentioning turning on BFD-per-linecard-basis
is mandatory. And BFD will not work if this step is forgotten. Yes,
I was able to configure everything. Just, it would not work and
got stuck with the previous error-code. Which I was challenged throwing
search engine magic after, finding useful information on.
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> David Hubbard
> Sent: Saturday, June 29, 2019 4:14 AM
>
> What platform are you on? I ran into numerous issues with XR + BFD on
> NCS5501-SE hardware; worked with TAC and confirmed. It's broken for
> bundle interfaces (gives an error, won't take the config), broken for BGP
> (takes the config without error but doesn't work), and broken if VRRP is in
> use. It will only work on a single physical link on that platform. We swapped
> out for Arista 7280's ultimately.
>
Was it recently (recent code release) please? Would like to know if this problem still exists or whether it might have been solved by now.
Thank you

adam

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