cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
864
Views
0
Helpful
3
Replies

OSPF: Fast Hellos

kozorezdi
Level 1
Level 1

Hello everyone,

I know the rule: all ospf timers should be the same on all network segment.  But it looks like, I can move step by step (interface by interface) to fast hellos (ip ospf dead-interval minimal hello-multiplier 5) without any issues with OSPF.

Another words on the same router can coexist OSPF with def. timers and a few specific PtP interfaces with Fast Hellos.  Is it correct?

Do you recommend to adjust the OSPF timers like this?

--

Thank you in advance,

Dmitry

2 Accepted Solutions

Accepted Solutions

ROTURNER_2
Level 1
Level 1

Hello Dmitry

I'm not sure if you mean this but I configured ip ospf fast hello's on different segments on Cat 3750 so some segments had fast hello's whilst others had standard  hello's and all sort of fine. My problem was I had Cat 3750G which does not support ip ospf fast hello and lost neighbors if you did work in the configuration.

However the point is you can configure on point to point as this is a segment and have standard on other segments together etc.

I hope this helps you regards Roger.

View solution in original post

Joseph W. Doherty
Hall of Fame
Hall of Fame

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Yes you can do that, and when deciding which links might benefit from fast hellos, consider those where connectivity to the OSPF neighbor can be loss but link remains up, e.g. two routers Ethernet connected via a switch.

If the link is true p-2-p, usually neigbor failure will take the link down and OSPF will see the loss before it would via its hellos.

View solution in original post

3 Replies 3

ROTURNER_2
Level 1
Level 1

Hello Dmitry

I'm not sure if you mean this but I configured ip ospf fast hello's on different segments on Cat 3750 so some segments had fast hello's whilst others had standard  hello's and all sort of fine. My problem was I had Cat 3750G which does not support ip ospf fast hello and lost neighbors if you did work in the configuration.

However the point is you can configure on point to point as this is a segment and have standard on other segments together etc.

I hope this helps you regards Roger.

Joseph W. Doherty
Hall of Fame
Hall of Fame

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Yes you can do that, and when deciding which links might benefit from fast hellos, consider those where connectivity to the OSPF neighbor can be loss but link remains up, e.g. two routers Ethernet connected via a switch.

If the link is true p-2-p, usually neigbor failure will take the link down and OSPF will see the loss before it would via its hellos.

kozorezdi
Level 1
Level 1

Thank you Roger and Joseph for sharing your knowledge and practical experience.  Now I understand how to use it better.  Thank you!

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Innovations in Cisco Full Stack Observability - A new webinar from Cisco