[j-nsp] load balancing between multiple BGP links

[Harry Reynolds]

The link bandwidth community, as of 5.6, should balance accordingly:


http://www.juniper.net/techpubs/software/junos/junos56/rn-sw-56/html/rn-
sw-563.html#1130062

BGP multipath link-bandwidth attribute--When per-packet load-balancing
is enabled, you can specify bandwidth values resulting in unequally
distributed traffic when you set up a community policy for BGP multipath
path selection. By default, when you use BGP multipath, the router
distributes traffic equally among the several paths it calculates. To
configure an unequal distribution, include the bandwidth attribute,
specifying the local autonomous system and link bandwidth in bytes per
second, at the [edit policy-options community name] hierarchy level. The
show route detail and show route forwarding-table commands display the
new output. [Policy, Command Reference]  

HTHs

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Alok
> Sent: Wednesday, September 14, 2005 6:08 AM
> To: Guy Davies; Joe Shen; juniper-nsp at puck.nether.net
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [j-nsp] load balancing between multiple BGP links
> 
> 
> ----- Original Message -----
> From: "Guy Davies" <Guy.Davies at telindus.co.uk>
> To: "Joe Shen" <sj_hznm at yahoo.com.cn>; <juniper-nsp at puck.nether.net>
> Cc: <cisco-nsp at puck.nether.net>
> Sent: Wednesday, September 14, 2005 4:20 PM
> Subject: RE: [j-nsp] load balancing between multiple BGP links
> 
> 
> > Hi Joe,
> >
> > It can't with the physical layout you described.  BGP 
> selects one next-hop
> as the best (and only one).  The only way to load share is to 
> have two (or
> more) parallel links between just two routers.  You then 
> create a static
> route on each end via each physical next-hop to the loopback 
> on the far end
> router.  Then, you setup an ebgp multihop session between the 
> loopbacks on
> the two routers.  That then uses IGP load sharing to balance 
> traffic across
> the two parallel links.
> >
> 
> Anyone knows what to expect in this scenario?
> 
> R1===========R2
> 
> EBGP multihop between them over 2 links
> link 1 =10Mbps
> link 2 = 20 Mbps
> 
> total traffic = 25Mbps
> 
> Is there a way to ensure that link 1 doesnt get choked?
> 
> 
> -thanks
> Alok
> 
> 
> 
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