[j-nsp] Default OSPF Equal Cost Behaviour - EX Switches

[Harry Reynolds]

Yes, per-packet really means per-flow. The default is per-prefix. Have to use mlpp to get per-packet.

Regards




 

-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Paul Stewart
Sent: Thursday, May 20, 2010 5:52 PM
To: juniper-nsp at puck.nether.net
Subject: [j-nsp] Default OSPF Equal Cost Behaviour - EX Switches

Hi there....

 

I opened a JTAC ticket this evening and looking for some opinion - after I closed the case I'm not sure of what I was told...

 

The ticket was opened because leaving a EX4200 VC there are two GigE connections going to a Cisco 6500 - so equal cost OSPF.  According to the routing table only one of those links was being selected (there was no default per packet or per destination load balancing occurring).

 

The guy at JTAC suggested a policy as:

 

paul at dis1.lansdowne1> show configuration policy-options policy-statement load-balancing

then {

    load-balance per-packet;

}

 

paul at dis1.lansdowne1> show configuration protocols ospf

export [ ospf_redistributes load-balancing ];

area 0.0.0.0 {

    interface vlan.130;

    interface vlan.904;

    interface vlan.971;

}

 

As there is quite a bit of voice traffic involved I asked if this was really per packet or if it was "per flow" as he had mentioned.  I was told that even though the configuration uses the wording "per-packet" that it's really per flow occurring.  It does appear to actually be some kind of source/destination hash similar or if not identical to default Cisco behaviour ... can anyone confirm that for me?  I'd rather avoid per packet load balancing if possible and stick to a round "round robin" per destination format if possible...

 

It's running JTAC recommended JunOS 10.0R3.10

 

Thanks for your input,

 

Paul

 

 

 

 

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