Routing
Routing

Need Help with bgp return traffic towards customer

‎07-31-2019 06:34 AM

Hi All,

 

I have created network diagram and attached to this ticket. kindly check for better understanding. 

 

We have customer who we providing transit capacity, he came back to us and  requested for CDN content from one of our content providers that we peer with. Now he needs the traffic from the CDN provider to be directed via seperate link and not through the current link that he uses to pick internet traffic. the physical link between his router and our router is just one and we just established 2nd bgp session with new P2P IPs. he wants to see if we can have traffic from CDN provider to exit via this 2nd link towards his network and all other traffic goes over other link. he is announcing his prefixes to us on both eBGP sessions and our router is selecting one of the links as active and putting that path in the routing table. this means as it is, all traffic heading to his ASN, will always use one link. can we do some form of PBR that says, if traffic is sourced from CDN ASN and destination is this cusotmer ASN, we route it to 2nd bgp link. all other traffic use the internet link. how can we approach this ? 

 

Appreacia

 

Regards,
Lish
FON

Attachments

8 REPLIES 8
Routing

Re: Need Help with bgp return traffic towards customer

‎07-31-2019 07:34 AM

Hello,

Yes it can be achieved by appliying an import policy on eBGP neighbors and configuring high local-prefence for content provider route on that eBGP neighbor.

Please refer following example:

https://www.juniper.net/documentation/en_US/junos/topics/topic-map/bgp-local-preference.html

 

For import policy on eBGP neighbor you can match from bgp, from route-filter <CDN route> exact, then local-preferecne 150.

Thanks
Vishal

 

 

Routing

Re: Need Help with bgp return traffic towards customer

‎08-01-2019 01:15 AM

Hi Vishal,

The customer is announcing same prefixes to us on both eBGP sessions. local pref will help me prefer the prefixes on one of the links. what i need is return traffic from the internet/CDN to routed differently towards the customer. traffic from CDN to exit via eBGP link 2 and other internet traffic to exit via link 1. 

 

I have FBF setup working currently (filter applied at router-2 on interface facing router-1. it matches on source-prefix-list (CDN prefixes) and destination prefix-list (customer prefixes) but its too brutal, we cant do this for every other customer that needs this kind of setup. is there another work around to achieve this?.

Regards,
Lish
FON
Routing

Re: Need Help with bgp return traffic towards customer

‎08-01-2019 02:58 AM

You are right that with FBF you can't use ASN or communities or other simple means to ID route sources for this type of application on the return path.  If you can maintain a prefix list FBF will be a way to accomplish this.

 

The only other option I see is to move the CDN client connection into a virtual router routing instance.  Then make a separate peering from here to the CDN and have prefixes learned this path local pref preffred.  This would create a clean bidirectional path and keep the original as a backup.

 

Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
Routing

Re: Need Help with bgp return traffic towards customer

‎08-01-2019 04:17 AM

Hello,

 


@lish wrote:

 

I have FBF setup working currently (filter applied at router-2 on interface facing router-1. it matches on source-prefix-list (CDN prefixes) and destination prefix-list (customer prefixes) but its too brutal, we cant do this for every other customer that needs this kind of setup. is there another work around to achieve this?.


 

SCU/DCU a.k.a. QPPB in Cisco speak was created to cater for such scenarios.

Rough algorithm:

0/ create SCU class

1/ mark BGP CDN routes with this SCU class

2/ create OUTPUT forwarding-table-filter matching on customer prefix-list _AND_ SCU class above then FBF this traffic as You do now.

Bonus points - You can use DCU in place of customer prefix-list but I haven't tested SCU+DCU together in recent JUNOS versions.

HTH

Thx
Alex

_____________________________________________________________________

Please ask Your Juniper account team about Juniper Professional Services offerings.
Juniper PS can design, test & build the network/part of the network as per Your requirements

+++++++++++++++++++++++++++++++++++++++++++++

Accept as Solution = cool !
Accept as Solution+Kudo = You are a Star !
Highlighted
Routing

Re: Need Help with bgp return traffic towards customer

‎08-05-2019 12:11 AM

HI Alex,

 

I have the CDN + plus other local traffic in SCU already, so i can just use it in the FBF filter... i have one concern: the interface where i enabled source-class usage (input) is the same interface where ama applying this FBF filter as input also, is this OK? will the CDN traffic be classified in the SCU-class before the filter is processed ? 

 

which one is processed first between the accounting SCU and filtering ?

Regards,
Lish
FON
Routing

Re: Need Help with bgp return traffic towards customer

‎08-05-2019 12:21 AM

Hi Steve,

 


@spuluka wrote:
Then make a separate peering from here to the CDN and have prefixes learned this path local pref preffred.  

 


you mean peering directly from this VR to the CDN ASN ? the CDN peering is happening at another router in the network. i only have the CDN prefixes present in the network with specific community identifying them.. or am i understnding the message wrongly ? 

Regards,
Lish
FON
Routing

Re: Need Help with bgp return traffic towards customer

‎08-05-2019 03:08 AM

Sorry for the lack of clarity, I mean peering from the VR to your side peer of the CDN.  

 

Since the issue is return traffic you would need to get these two customer prefixes as a return route to your own CDN peer directly so that this path is the local preference path pulling that return traffic out of the stream inbound to your network.

 

Your CDN side peer could also learn those same routes from the existing path as a backup in the event of failure on the dedicated side.

 

Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
Routing

Re: Need Help with bgp return traffic towards customer

‎08-05-2019 10:51 AM

Hello,

According to Figure 1  diagram https://www.juniper.net/documentation/en_US/junos/topics/concept/adaptive-services-packet-flow-pic.h... , SCU is not executed on interface input. You need to add SCU to OUTPUT FORWARDING TABLE FILTER for my idea to work, re-read my earlier post point # 2.

HTH

Thx
Alex

_____________________________________________________________________

Please ask Your Juniper account team about Juniper Professional Services offerings.
Juniper PS can design, test & build the network/part of the network as per Your requirements

+++++++++++++++++++++++++++++++++++++++++++++

Accept as Solution = cool !
Accept as Solution+Kudo = You are a Star !