SD-WAN

Hi All,

I was wondering what happens in the following setup:
- WAN: 1 internet connection and ISP router is the DHCP server with a single public IP in the pool
- 2 SSR Spokes in HA mode
- both Spokes are connected to the ISP router using SharedMAC

Let's say a power outage happens and all 3 routers restart. When the first SSR Spoke boots, the CentOS physical WAN interface will learn the public IP via DHCP.
The DHCP server assigns its only public IP to the physcial MAC address of the CentOS. 
After that the 128T service starts, the CentOS physical interface "dissapears" and the new logical WAN interface (in the routingEngine namespace) will try to get an IP for itself via DHCP. However it will use its own SharedMAC address instead of the CentOS physical MAC address. The DHCP server will not provide the IP as it is already reserved for the pyhsical MAC. 

Can you confirm this or am I thinking wrong?

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TAMAS VARGA
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Hi,

I think there are 2 thing to address related to your question:

1. You don't need to configure WAN interface in CentOS
So you can go in your CentOS and disable your interface in wan interface config file: /etc/sysconfig/network-scripts/ifcfg-...
In this case, your DHCP server will assign an IP based in you SSR MAC address

2. You could have WAN interface configured in physical node 1 and it can be used by physical node 2. With other words, you can share the link between the nodes (as the secondary node is in hot-standy state). This is done via the Service Route configuration.

Hope it helps.

Regards,
Ivan



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Ivan Stanev
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Original Message:
Sent: 11-14-2022 09:08
From: TAMAS VARGA
Subject: SSR DHCP handling

Hi All,

I was wondering what happens in the following setup:
- WAN: 1 internet connection and ISP router is the DHCP server with a single public IP in the pool
- 2 SSR Spokes in HA mode
- both Spokes are connected to the ISP router using SharedMAC

Let's say a power outage happens and all 3 routers restart. When the first SSR Spoke boots, the CentOS physical WAN interface will learn the public IP via DHCP.
The DHCP server assigns its only public IP to the physcial MAC address of the CentOS. 
After that the 128T service starts, the CentOS physical interface "dissapears" and the new logical WAN interface (in the routingEngine namespace) will try to get an IP for itself via DHCP. However it will use its own SharedMAC address instead of the CentOS physical MAC address. The DHCP server will not provide the IP as it is already reserved for the pyhsical MAC. 

Can you confirm this or am I thinking wrong?

------------------------------
TAMAS VARGA
------------------------------