in Azure after i established Vnet to Vnet connection, i want to see the routing table where is the routes from other vnet is received? how i can see this

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in Azure after i established Vnet to Vnet connection, i want to see the routing table where is the routes from other vnet is received? how i can see this

ZEIN Ahmed OBS/S EUR 125

i have created Virtual Network Gateways on 2 different Vnets and created connections between both , now up and connected.
how i can see the updated routes of each Vnet on the other side? i cannot find a routing table on the Vnet or on the Gateways?

ZEIN Ahmed OBS/S EUR 125 Reputation points

2023-09-16T21:19:48.56+00:00

that means, the only way to see thr routing table in a particular Vnet is to have a VM-NIC?
aside from the VM-NIC (assume i do not create any NIC)
does the route server can help on that?
does the BGP peering help on that?

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ZEIN Ahmed OBS/S EUR 125 Reputation points

2023-09-16T21:19:48.56+00:00

that means, the only way to see thr routing table in a particular Vnet is to have a VM-NIC?
aside from the VM-NIC (assume i do not create any NIC)
does the route server can help on that?
does the BGP peering help on that?

Answer 1

TP 126.3K Volunteer Moderator

Hi,

In the portal, if you navigate to network interface associated with VNet, you can view Effective Routes. For example, navigate to a VM -- Settings -- Networking, click on network interface, and then Help -- Effective routes.

Please click Accept Answer if the above was useful.

Thanks.

-TP

ZEIN Ahmed OBS/S EUR 125 Reputation points

2023-09-16T21:04:50.25+00:00

i know , but i want to see the route from the GW or the vNet itself, assume that i do not have any VMs in this vNET (as a service vNEt which i will use to connect other vNETs)
does it make sense?
TP 126.3K Reputation points Volunteer Moderator

2023-09-16T21:20:53.2166667+00:00

Unfortunately I don't know of way to see effective routes for VNet as you describe. Only for network interface and virtual hub. I did search and found that the feature has been requested years ago:

https://github.com/MicrosoftDocs/azure-docs/issues/53704
ZEIN Ahmed OBS/S EUR 125 Reputation points

2023-09-17T08:51:16.9066667+00:00

How the 2 GWs propoagate the routes to each other?
i did not make any static routes (i think this is not applicable, as i am using route-based GW)
and no BGP peers shown at all!! however i have enabled the BGP!

is that a default or automatic propagation ?
GitaraniSharma-MSFT 50,096 Reputation points Microsoft Employee Moderator

2023-09-18T08:59:22.39+00:00
Hello @ZEIN Ahmed OBS/S EUR ,

Yes, Azure adds default system routes for different Azure capabilities. Depending on the capability, Azure adds optional default routes to either specific subnets within the virtual network, or to all subnets within a virtual network. One of such optional default route is called Virtual network gateway.

Virtual network gateway: One or more routes with Virtual network gateway listed as the next hop type are added when a virtual network gateway is added to a virtual network. The source is also virtual network gateway, because the gateway adds the routes to the subnet. If your on-premises network gateway exchanges border gateway protocol (BGP) routes with a virtual network gateway, the system adds a route for each route. These routes are propagated from the on-premises network gateway.

Refer: https://learn.microsoft.com/en-us/azure/virtual-network/virtual-networks-udr-overview#optional-default-routes

Also, if you check Azure VPN gateway FAQ, you can find the below:

What address prefixes will Azure VPN gateways advertise to me?

The gateways advertise the following routes to your on-premises BGP devices:

Your virtual network address prefixes.

Address prefixes for each local network gateway connected to the Azure VPN gateway.

Routes learned from other BGP peering sessions connected to the Azure VPN gateway, except for the default route or routes that overlap with any virtual network prefix.

Refer: https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-vpn-faq#what-address-prefixes-will-azure-vpn-gateways-advertise-to-me

So, basically, the Azure VPN gateway will advertise a mix of default (which are static) routes and BGP routes (if BGP is enabled).

If you would like to retrieve a list of routes the virtual network gateway is advertising to the specified peer or a list of routes the virtual network gateway has learned, including routes learned from BGP peers, you can use the below REST APIs:

https://learn.microsoft.com/en-us/rest/api/network-gateway/virtual-network-gateways/get-advertised-routes?tabs=HTTP

https://learn.microsoft.com/en-us/rest/api/network-gateway/virtual-network-gateways/get-learned-routes?tabs=HTTP

Kindly let us know if the above helps or you need further assistance on this issue.

Regards,

Gita

Answer 2

Tushar Kumar 3,371 MVP

When you create Site to Site connection route are learned by the Gateway so you will not find any Route table resource in Azure. Route table is used if you want to enforce any custom route to your subnets (e.g. all traffic to firewall )

You can check on any Machine the effective route If you don't have any Machine in the Network create NIC for the same

Under Settings on the left, select Networking, and navigate to the network interface resource by selecting its name. View network interfaces

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ZEIN Ahmed OBS/S EUR 125 Reputation points

2023-09-16T21:21:31.3966667+00:00

that means, the only way to see thr routing table in a particular Vnet is to have a VM-NIC?
aside from the VM-NIC (assume i do not create any NIC)
does the route server can help on that?
does the BGP peering help on that?
Tushar Kumar 3,371 Reputation points MVP

2023-09-16T21:32:40.9633333+00:00

Yes, Using BGP definitely help(in learning routes not showing routes) since BGP enables multiple gateways to learn and propagate prefixes from different networks, whether they're directly or indirectly connected.

https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-bgp-resource-manager-ps?toc=%2Fazure%2Fvirtual-network%2Ftoc.json

Please click "Accept as Answer" if this helps.
ZEIN Ahmed OBS/S EUR 125 Reputation points

2023-09-17T08:51:29.0233333+00:00

How the 2 GWs propoagate the routes to each other?
i did not make any static routes (i think this is not applicable, as i am using route-based GW)
and no BGP peers shown at all!! however i have enabled the BGP!

is that a default or automatic propagation ?
Tushar Kumar 3,371 Reputation points MVP

2023-09-17T09:49:33.1133333+00:00

RouteBased VPNs were previously called dynamic routing gateways in the classic deployment model. RouteBased VPNs use "routes" in the IP forwarding or routing table to direct packets into their corresponding tunnel interfaces. The tunnel interfaces then encrypt or decrypt the packets in and out of the tunnels. The policy (or traffic selector) for RouteBased VPNs are configured as any-to-any (or wild cards). The value for a RouteBased VPN type is RouteBased.

To understand it easily when you are creating S2S(IPSec) vpn to on-prem or other cloud you create local network gateway to feed in the ranges that works as routes. Consider this same as that it's just under the hood MS is taking care for you but underlying tech is same it's connection between 2 gateways.

Please Click "Accept as answer" if this helps.

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in Azure after i established Vnet to Vnet connection, i want to see the routing table where is the routes from other vnet is received? how i can see this

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