DMZ Link bandwidth/multihoming/equal cost loadsharing/balancing

Answered Question
Aug 25th, 2010
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Friends,

can you suggest best ways to load balancing in a multihoming scenarion in which i have multiple links from different service providers, all of them are equal bandwidth links.?

what is the difference between load balancing and load sharing?

where is dmz-link bandwidth is used.is it applicable to equal cost link load balacing in multihome scenarion?


thanks in advance for your help as usual


regards

V

Correct Answer by Giuseppe Larosa about 6 years 8 months ago

Hello Porkovan,


>> dmz-link bandwidth is used.is it applicable to equal cost link load balacing in multihome scenarion?


natural use of dmz-link bandwidth is with links of different speeds leading to the same peer AS


if all your links are of equal speeds you don't need it


>> to load balancing in a multihoming scenarion in which i have multiple links from different service providers, all of them are equal bandwidth links.?


you will need two commands


router bgp XXX

maximum-paths N


+

an hidden command in order to install routes coming from different peer AS


bgp bestpath as-path multipath-relax



Note:

if you plan to accept multiple full BGP tables the possible impacts of BGP multipath on memory use of routing table and CEF tables has to be taken in account.

The above setup can be a safe and wise move if you are accepting only a default route or few IP prefixes from each provider.

Impact may vary also depending on platforms you use: running out of CEF tables on a C6500 is dramatic for example.



Hope to help

Giuseppe

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Correct Answer
Giuseppe Larosa Wed, 08/25/2010 - 04:09
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Hello Porkovan,


>> dmz-link bandwidth is used.is it applicable to equal cost link load balacing in multihome scenarion?


natural use of dmz-link bandwidth is with links of different speeds leading to the same peer AS


if all your links are of equal speeds you don't need it


>> to load balancing in a multihoming scenarion in which i have multiple links from different service providers, all of them are equal bandwidth links.?


you will need two commands


router bgp XXX

maximum-paths N


+

an hidden command in order to install routes coming from different peer AS


bgp bestpath as-path multipath-relax



Note:

if you plan to accept multiple full BGP tables the possible impacts of BGP multipath on memory use of routing table and CEF tables has to be taken in account.

The above setup can be a safe and wise move if you are accepting only a default route or few IP prefixes from each provider.

Impact may vary also depending on platforms you use: running out of CEF tables on a C6500 is dramatic for example.



Hope to help

Giuseppe

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