Xjyuk

Is an early checkout possible at a hotel before its reception opens?

Why would future John risk sending back a T-800 to save his younger self?

When conversion from Integer to Single may lose precision

Find the Factorial From the Given Prime Relationship

Watts vs. Volt Amps

"You've got another thing coming" - translation into French

Implement Homestuck's Catenative Doomsday Dice Cascader

Smooth switching between 12 V batteries, with a toggle switch

How do I write "Show, Don't Tell" as a person with Asperger Syndrome?

What could have caused a rear derailleur to end up in the back wheel suddenly?

Passing multiple files through stdin (over ssh)

Inconsistent behavior of compiler optimization of unused string

Why only the fundamental frequency component is said to give useful power?

Random Unitary Matrices

How to Analytically Solve this PDE?

What's up with this leaf?

Should I compare a std::string to "string" or "string"s?

Frame failure sudden death?

Is the term 'open source' a trademark?

What can I, as a user, do about offensive reviews in App Store?

How to chain Python function calls so the behaviour is as follows

Why was the Sega Genesis marketed as a 16-bit console?

Facebook Marketing API asset access suddenly denied

Using a found spellbook as a Sorcerer-Wizard multiclass

BGP convergence issue

Inbound BGP load-balancing from same ISP routerBest practice for the combination of HSRP and ECMPImpact of IOS BGP soft-reconfiguration-inbound and peering optionsBGP - source routing breaking for some routesTwo ISP bgp topology?WAN connectivity down when BGP neighborship formedBYO thoughts on BGP routingBGP Route Dampaning - Not directly connected eBGP peers - EventsCisco BGP Graceful Restart behaviorlocal pref question

2

I have 2 different carriers on my router and I have set weight to 350 for my first carrier to force it for my outbound traffic, and I set second carrier weight to 300.

I am receiving BGP full table from both providers.

My problem here is when my BGP session with carrier #1 disconnects, it takes about 5-10 minutes for the routes received from carrier #1 to be deleted from my routing table so to force my outbound to second carrier.
How can I solve this issue? Is there anyway when BGP session with carrier #1 disconnects, all routes are removed immediately ?

cisco routing bgp

share|improve this question

edited 1 hour ago

Ron Trunk

42.5k33989

asked 12 hours ago

BlackmetalBlackmetal

284

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Is it really 5-10 minutes, or is it 3 minutes (normal BGP timers)? When things stop working, it can seem like forever.
  
  – Ron Trunk
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  it takes about at least 5m, so whats your idea for solve this? how can if force immediately set next hop to my backup provider?
  
  – Blackmetal
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  A related question: If you prefer one carrier over the other, why are you receiving full routes? Why not a default route only? Processing 500,000 routes takes significant time, especially on a small router).
  
  – Ron Trunk
  10 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  You do not need the full routing table to have backups the way you describe; you only need default routes with different ADs. You could then have a faster failover.
  
  – Ron Maupin♦
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  A Cisco 2921, seriously? I'm amazed it's even able to hold 2 full tables. The root cause of your problems is that the CPU in those boxes are not able to cope with losing a full table. Either switch to defaults only (as was suggested in some answers) or upgrade to a model which was designed for this purpose.
  
  – Teun Vink♦
  7 hours ago
  

  
  
  
  

 | 
show 3 more comments

2

I have 2 different carriers on my router and I have set weight to 350 for my first carrier to force it for my outbound traffic, and I set second carrier weight to 300.

I am receiving BGP full table from both providers.

My problem here is when my BGP session with carrier #1 disconnects, it takes about 5-10 minutes for the routes received from carrier #1 to be deleted from my routing table so to force my outbound to second carrier.
How can I solve this issue? Is there anyway when BGP session with carrier #1 disconnects, all routes are removed immediately ?

cisco routing bgp

share|improve this question

edited 1 hour ago

Ron Trunk

42.5k33989

asked 12 hours ago

BlackmetalBlackmetal

284

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Is it really 5-10 minutes, or is it 3 minutes (normal BGP timers)? When things stop working, it can seem like forever.
  
  – Ron Trunk
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  it takes about at least 5m, so whats your idea for solve this? how can if force immediately set next hop to my backup provider?
  
  – Blackmetal
  11 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  A related question: If you prefer one carrier over the other, why are you receiving full routes? Why not a default route only? Processing 500,000 routes takes significant time, especially on a small router).
  
  – Ron Trunk
  10 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  You do not need the full routing table to have backups the way you describe; you only need default routes with different ADs. You could then have a faster failover.
  
  – Ron Maupin♦
  10 hours ago
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  A Cisco 2921, seriously? I'm amazed it's even able to hold 2 full tables. The root cause of your problems is that the CPU in those boxes are not able to cope with losing a full table. Either switch to defaults only (as was suggested in some answers) or upgrade to a model which was designed for this purpose.
  
  – Teun Vink♦
  7 hours ago
  

  
  
  
  

 | 
show 3 more comments

I have 2 different carriers on my router and I have set weight to 350 for my first carrier to force it for my outbound traffic, and I set second carrier weight to 300.

I am receiving BGP full table from both providers.

My problem here is when my BGP session with carrier #1 disconnects, it takes about 5-10 minutes for the routes received from carrier #1 to be deleted from my routing table so to force my outbound to second carrier.
How can I solve this issue? Is there anyway when BGP session with carrier #1 disconnects, all routes are removed immediately ?

cisco routing bgp

share|improve this question

edited 1 hour ago

Ron Trunk

42.5k33989

asked 12 hours ago

BlackmetalBlackmetal

284

share|improve this question

edited 1 hour ago

Ron Trunk

42.5k33989

asked 12 hours ago

BlackmetalBlackmetal

284

share|improve this question

edited 1 hour ago

Ron Trunk

42.5k33989

asked 12 hours ago

BlackmetalBlackmetal

284

edited 1 hour ago

Ron Trunk

42.5k33989

edited 1 hour ago

Ron Trunk

42.5k33989

asked 12 hours ago

BlackmetalBlackmetal

284

asked 12 hours ago

BlackmetalBlackmetal

284

2 Answers
2

active

oldest

votes

5

There are two issues here:

1. BGP keepalives are 60 seconds, and the hold down timer is 3 times that. So that's your lower limit, unless you work with your carrier and adjust your timers. You both need to have the same timer values.




2. You are receiving full routes from both carriers. That's over 400,000 routes from each carrier. So your router needs to process that many entries when a carrier drops a session. That can take time on a small router like a 2900.

One idea is to only receive default routes from your carrier. You can still use local preference to prioritize carriers, but it's much faster to process one route than 400,000. Don't forget that you are still limited by #1.

share|improve this answer

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Make that 770k routes per transit provider. BFD could help solve some of the issues with BGP hold timers.
  
  – Teun Vink♦
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  your mean is if i use local pref instead weight , it will process routes faster ? so in a case when one of my bgp session drop local pref change to second provider faster than weight atribute?
  
  – Blackmetal
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Blackmetal No. I assumed you meant local preference because of the value (350). Weight is usually a much higher value. But it's the same problem either way.
  
  – Ron Trunk
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  yes i know higher local pref will be better than weight, so if i use local pref i do not get faster route proccess when my bgp session disable?
  
  – Blackmetal
  9 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Neither one is faster. The problem is you have too many routes to process.
  
  – Ron Trunk
  9 hours ago
  

  
  
  
  

 | 
show 1 more comment

2

Another solution, as suggested by @ronmaupin 's comment, is to not accept any BGP routes at all and instead use static default routes (with different administrative distance for each ISP) along with object tracking.

You can ping an internal router of the ISP with IP SLA and use that to track the default route. That will fail over in a few seconds, instead of 3 minutes for BGP.

share|improve this answer

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i just tried change my parameter from weight to local prefrence and then shutdown my interface and i see right now it takes 1 minutes and 30 seconds for change to carrier 2! there is much difference between local pref and weight, anyone knows why ?
  
  – Blackmetal
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Shutting down the interface converges much faster than losing a peer.
  
  – Ron Trunk
  2 hours ago
  

  
  
  
  

add a comment | 

Your Answer

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "496"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fnetworkengineering.stackexchange.com%2fquestions%2f59565%2fbgp-convergence-issue%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

5

There are two issues here:

1. BGP keepalives are 60 seconds, and the hold down timer is 3 times that. So that's your lower limit, unless you work with your carrier and adjust your timers. You both need to have the same timer values.




2. You are receiving full routes from both carriers. That's over 400,000 routes from each carrier. So your router needs to process that many entries when a carrier drops a session. That can take time on a small router like a 2900.

One idea is to only receive default routes from your carrier. You can still use local preference to prioritize carriers, but it's much faster to process one route than 400,000. Don't forget that you are still limited by #1.

share|improve this answer

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Make that 770k routes per transit provider. BFD could help solve some of the issues with BGP hold timers.
  
  – Teun Vink♦
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  your mean is if i use local pref instead weight , it will process routes faster ? so in a case when one of my bgp session drop local pref change to second provider faster than weight atribute?
  
  – Blackmetal
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Blackmetal No. I assumed you meant local preference because of the value (350). Weight is usually a much higher value. But it's the same problem either way.
  
  – Ron Trunk
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  yes i know higher local pref will be better than weight, so if i use local pref i do not get faster route proccess when my bgp session disable?
  
  – Blackmetal
  9 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Neither one is faster. The problem is you have too many routes to process.
  
  – Ron Trunk
  9 hours ago
  

  
  
  
  

 | 
show 1 more comment

5

There are two issues here:

1. BGP keepalives are 60 seconds, and the hold down timer is 3 times that. So that's your lower limit, unless you work with your carrier and adjust your timers. You both need to have the same timer values.




2. You are receiving full routes from both carriers. That's over 400,000 routes from each carrier. So your router needs to process that many entries when a carrier drops a session. That can take time on a small router like a 2900.

One idea is to only receive default routes from your carrier. You can still use local preference to prioritize carriers, but it's much faster to process one route than 400,000. Don't forget that you are still limited by #1.

share|improve this answer

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Make that 770k routes per transit provider. BFD could help solve some of the issues with BGP hold timers.
  
  – Teun Vink♦
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  your mean is if i use local pref instead weight , it will process routes faster ? so in a case when one of my bgp session drop local pref change to second provider faster than weight atribute?
  
  – Blackmetal
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Blackmetal No. I assumed you meant local preference because of the value (350). Weight is usually a much higher value. But it's the same problem either way.
  
  – Ron Trunk
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  yes i know higher local pref will be better than weight, so if i use local pref i do not get faster route proccess when my bgp session disable?
  
  – Blackmetal
  9 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Neither one is faster. The problem is you have too many routes to process.
  
  – Ron Trunk
  9 hours ago
  

  
  
  
  

 | 
show 1 more comment

There are two issues here:

1. BGP keepalives are 60 seconds, and the hold down timer is 3 times that. So that's your lower limit, unless you work with your carrier and adjust your timers. You both need to have the same timer values.




2. You are receiving full routes from both carriers. That's over 400,000 routes from each carrier. So your router needs to process that many entries when a carrier drops a session. That can take time on a small router like a 2900.

One idea is to only receive default routes from your carrier. You can still use local preference to prioritize carriers, but it's much faster to process one route than 400,000. Don't forget that you are still limited by #1.

share|improve this answer

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

share|improve this answer

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

answered 10 hours ago

Ron TrunkRon Trunk

42.5k33989

2

Another solution, as suggested by @ronmaupin 's comment, is to not accept any BGP routes at all and instead use static default routes (with different administrative distance for each ISP) along with object tracking.

You can ping an internal router of the ISP with IP SLA and use that to track the default route. That will fail over in a few seconds, instead of 3 minutes for BGP.

share|improve this answer

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i just tried change my parameter from weight to local prefrence and then shutdown my interface and i see right now it takes 1 minutes and 30 seconds for change to carrier 2! there is much difference between local pref and weight, anyone knows why ?
  
  – Blackmetal
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Shutting down the interface converges much faster than losing a peer.
  
  – Ron Trunk
  2 hours ago
  

  
  
  
  

add a comment | 

2

Another solution, as suggested by @ronmaupin 's comment, is to not accept any BGP routes at all and instead use static default routes (with different administrative distance for each ISP) along with object tracking.

You can ping an internal router of the ISP with IP SLA and use that to track the default route. That will fail over in a few seconds, instead of 3 minutes for BGP.

share|improve this answer

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i just tried change my parameter from weight to local prefrence and then shutdown my interface and i see right now it takes 1 minutes and 30 seconds for change to carrier 2! there is much difference between local pref and weight, anyone knows why ?
  
  – Blackmetal
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Shutting down the interface converges much faster than losing a peer.
  
  – Ron Trunk
  2 hours ago
  

  
  
  
  

add a comment | 

Another solution, as suggested by @ronmaupin 's comment, is to not accept any BGP routes at all and instead use static default routes (with different administrative distance for each ISP) along with object tracking.

You can ping an internal router of the ISP with IP SLA and use that to track the default route. That will fail over in a few seconds, instead of 3 minutes for BGP.

share|improve this answer

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989

share|improve this answer

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989

answered 9 hours ago

Ron TrunkRon Trunk

42.5k33989