[j-nsp] BFD advice

George Yalamov georgi.yalamov at btc-net.bg
Thu Aug 4 07:51:29 EDT 2005


I've made some tests with cisco and juniper devices , with tunned IGP 
timers for fast convergence.To avoid  lost of light i use couple of 
switches between nodes.

Other tests was only between M series with bfd timers for example from 
10ms  to 200ms and I receive similar results. That seems to be caused 
from IGP convergence time ot measure mistake.

We plan to use BFD under SDH links , but now  I have ability to use test 
only with ethernet interfaces.  From some time I'll try with STM interfaces.

I work in BTC for only 4 mounths, and don't have intofmation about that 
NGN trial, I'll ask Nedialko (actualy he is my manager now) for some 
notes about.


Rafal Szarecki (WA/EPO) wrote:
> George,
> If you connect routers over dark-fibers or SDH, and simulte failure by removing/cuting of fiber, then detection of fail can be quicker then with BFD. This is because Lost-of-Light, AIS, RDI are asynchounus, do not depend from interval, so can be faster.
> I guess You connect routers over fiber back-to-back. Then observed 200ms or more is rather effect of spf-delay then BFD.
> BFD is usefull if:
>  - routers are connected via Eth. Switch
>  - L2 protocols or handling hardware fail, while L1(lasers, SDH driver) handling HW works fine. ( There is light on fiber, no AIS, no RDI...)
> Rafaі Jan Szarecki JNCIE
> Senior Consultant - Datacom Networks
> Ericsson Poland EPO/S/D
> Office: +48 22 6916635
> ECN:    837 6635
> Mobile: +48 602418971
> Skype: callto://Rafal_Szarecki <callto://Rafal_Szarecki/> 
>>-----Original Message-----
>>From: juniper-nsp-bounces at puck.nether.net 
>>[mailto:juniper-nsp-bounces at puck.nether.net]On Behalf Of 
>>Rafal Szarecki (WA/EPO)
>>Sent: Thursday, August 04, 2005 11:16 AM
>>To: George Yalamov; juniper-nsp at puck.nether.net
>>Subject: RE: [j-nsp] BFD advice
>>I was paly with BFD in _lab env._ only, but I have no 
>>problems with interval at few ms level. I do this year ago in 
>>lab test in Bulgaris togheder with BTC. As fare as I remember 
>>we was observe low the 30ms restoration in our lab network.
>>Person responsible from BTC for this tests was Nedialko 
>>Dimitrov (from BTC - your colegue). Test cases e.g. 
>>001.001.001 , 001.001.003.
>>If you look for fast convergency BFD helps to detect link 
>>failure, but then normal IS-IS/OSPF process start. To squize 
>>time I suggest to tune also SFP-delay parameter under [edit 
>>protocols isis]. (JUNOS 7.3 default 200ms, RFC standart 1s, 
>>minimum 50ms)
>>If you need experts support you can contact with local 
>>Ericsson office.
>>Rafaі Jan Szarecki JNCIE
>>Senior Consultant - Datacom Networks
>>Ericsson Poland EPO/S/D
>>Office: +48 22 6916635
>>ECN:    837 6635
>>Mobile: +48 602418971
>>Skype: callto://Rafal_Szarecki <callto://Rafal_Szarecki/> 
>>>-----Original Message-----
>>>From: juniper-nsp-bounces at puck.nether.net 
>>>[mailto:juniper-nsp-bounces at puck.nether.net]On Behalf Of 
>>>George Yalamov
>>>Sent: Wednesday, August 03, 2005 5:45 PM
>>>To: juniper-nsp at puck.nether.net
>>>Subject: [j-nsp] BFD advice
>>>Hi all,
>>>	Does any one have real life experance with BFD, tunning timers, 
>>>measurement of traffic disruption between 2 end points, 
>>>convergance time 
>>>in IGP (ISIS for example).
>>>I've tested this feature in lab environment with some M 
>>>boxes, and the 
>>>minimum time of traffic interruption was 200 - 400ms measured 
>>>with iperf.
>>>Any ideas?
>>>juniper-nsp mailing list juniper-nsp at puck.nether.net
>>juniper-nsp mailing list juniper-nsp at puck.nether.net

More information about the juniper-nsp mailing list