[j-nsp] Command to modify ADSPEC object default on PATH messages.

Harry Reynolds harry at juniper.net
Fri Aug 7 11:47:57 EDT 2009


We state we support the rfc, which I believe means we can process a Path message with such an Adspec, but AFAIK, there is no way to configure the ingress node to populate a GS based Adspec. JUNOS does mpls QoS via DiffServ TE, not IntServ.

HTHs




 

-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Thiago Drechsel
Sent: Friday, August 07, 2009 8:39 AM
To: Nalkhande Tarique Abbas
Cc: Juniper List
Subject: Re: [j-nsp] Command to modify ADSPEC object default on PATH messages.

Hi Nalkhande.

Thanks for your help.

MTU information goes inside the PATH message, on object ADSPEC -> "Default General Parameters" data fragment.

What I need is the command to include in the PATH Message the following
object:

ADSPEC -> "Guaranteed Service" data fragment (described on RFC2210, item
3.3.3)


Best regards.

-
Thiago Drechsel


On Fri, 2009-08-07 at 20:30 +0530, Nalkhande Tarique Abbas wrote:
> AFAIK, JUNOS uses the Adspec field for maximum transmission unit (MTU) 
> negotiation.
> 
> So when an LSP is created across a set of links with different MTU 
> sizes, the ingress router does not know what the smallest MTU is on 
> the LSP path. By default, the maximum packet size for the LSP is based 
> on the MTU for the outgoing interface for the LSP on the ingress router.
> 
> If this MTU is larger than the MTU of one of the intermediate links, 
> traffic might be dropped, because MPLS packets cannot be fragmented.
> 
> To prevent this type of packet loss in MPLS LSPs, you can configure 
> MTU signaling in RSVP. Juniper supports the Integrated Services object 
> for MTU signaling in RSVP.
> 
> MTU signaling in RSVP is disabled by default.
> To configure maximum transmission unit (MTU) signaling in RSVP, you 
> need to configure MPLS to allow IP packets to be fragmented before 
> they are encapsulated in MPLS. You also need to configure MTU signaling in RSVP.
> To configure MTU signaling in RSVP, include the path-mtu statement:
> 
> path-mtu {
> allow-fragmentation;
> rsvp {
> mtu-signaling;  <<--
> }
> }
> 
> lab at ntarique# run show mpls lsp transit detail Transit LSP: 1 sessions
> 
> 192.168.255.1
>   From: 192.168.255.7, LSPstate: Up, ActiveRoute: 1
> 
> ... truncated...
> 
>   FastReroute desired
>   PATH rcvfrom: 192.168.245.46 (so-0/2/1.0) 42 pkts
>   Adspec: received MTU 1500 sent MTU 1500  <<<---
>  
> 
> 
> Thanks & Regards,
> Tarique A. Nalkhande
> 
> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Thiago 
> Drechsel
> Sent: Friday, August 07, 2009 6:37 PM
> To: Juniper List
> Subject: [j-nsp] Command to modify ADSPEC object default on PATH 
> messages.
> 
> Hi list.
> 
> Does anybody know what is the configuration needed to add "Guaranteed 
> Service" parameters, on ADSPEC object (RSVP PATH messages)?
> 
> By default, I see that JUNOS only sends "Default General Parameters" 
> and "Controlled Load" within PATH....
> 
> Thank you!
> 

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