Routing

Hi,

I'm new in the J-NET Community. I hope this is the right forum for my question.

I'm involved in delivering a Two DC solution where core routers are MX and access-layer is comprised of EX VCs. One DC in in Madrid and the other one in Barcelona. I run MPLS/VPLS in the core in order to extend /24 vlans between both DCs (There are two LAN Extension Lines between both DCs)

As the "Implementing VPLS in DC networks" design guide recommends, I have allocated hosts in a way that all hosts in every vlan allocated in one DC are included in the first /25 and all hosts in the other datacenter are allocated in the last /25. Note all mask are /24 and MX are running irb and vrrp to serve as DGw for every vlan.

The point is I need to ensure customer external traffic to both DCs enters directly to the DC the target host is allocated in order to avoid traffic crossing the Madrid-Barcelona core lines.

Then, I wanted to announce every /24 from both DCs and at the same time one DC would announce the first /25s and the other DC the last /25s.

As from the MX point of view these vlans are directly connected, I do not have a nexthop to point the more specific /25 routes. Unfortunately, Junos does not support a static route pointing to an interface instead of a next-hop when you have a multpoint interface (Security reason to avoid sending ARPs? 😞             ). I can not set the specific routes towards "discard" because this would "blackhole" the traffic...

I could rise the VCs up L3 in each vlan and point the specific routes towards them, but I do not like this option as I would innecesarily send all traffic to be L3 processed by the VCs.

Is there any other solution I could generate  the /25s? Any kind of cisco's "bgp inject-map" feature?

Thanks in advance,

Chema.

hi,

> The point is I need to ensure customer external traffic to both DCs enters directly to the DC the target host is

> allocated in order to avoid traffic crossing the Madrid-Barcelona core lines.

could you describe the scenario you would like to avoid ? In some cases you may need to cross the Madrid<>Barcelona

connection (if traffic src is not in the same city as destination network /25). Do you want to use another, non-VPLS path ? 

Back to the question. Similar topic has been discusses in thread:

http://forums.juniper.net/t5/Routing/Junos-equivalent-to-conditiona l-route-injection-IOS-bgp-inject/td-p/25900

Based on my short testing, for direct route 10.55.1.0/24 you should be able to create /25 in routing table:

static {
    route 10.55.1.0/25 {
        receive;
        no-install;
    }
}

'no-install'  was required to avoid problems with ARP. Tested on M7i  (old Junos 8.5).  Test the solution before deployment !

jtb

Thanks JTB!

The "receive" and "no-install" keywords work as expected. 

---

@jtb wrote:

hi,

 

> The point is I need to ensure customer external traffic to both DCs enters directly to the DC the target host is

> allocated in order to avoid traffic crossing the Madrid-Barcelona core lines.

 

could you describe the scenario you would like to avoid ? In some cases you may need to cross the Madrid<>Barcelona

connection (if traffic src is not in the same city as destination network /25). Do you want to use another, non-VPLS path ? 

 

Back to the question. Similar topic has been discusses in thread:

http://forums.juniper.net/t5/Routing/Junos-equivalent-to-conditiona l-route-injection-IOS-bgp-inject/td-p/25900

 

Based on my short testing, for direct route 10.55.1.0/24 you should be able to create /25 in routing table:

 

static {
    route 10.55.1.0/25 {
        receive;
        no-install;
    }
}

 

'no-install'  was required to avoid problems with ARP. Tested on M7i  (old Junos 8.5).  Test the solution before deployment !

jtb

---

Thank you very much for your help.

Regards,

Chema.