Route prefference

[Sarafianl1980]

Hi All,

Can anyone help me understand the route path preference here please?  I'm trying to understand which path a packet to 11.187.1.7 will take when dealing with VRF's on a single L3 switch?

Packet comes in on this SVI

SwitchA
interface Vlan3371
ip address 11.187.7.129 255.255.255.248
no ip redirects
no ip unreachables
no ip proxy-arp
no ip mroute-cache
standby delay minimum 20 reload 25
standby 71 ip 11.187.7.131
standby 71 timers 5 15
standby 71 priority 120
standby 71 preempt
arp timeout 300
end

Packet leaves this SVI and has two choices:

Choice1 via Global r-table

SwitchA#sh ip route 11.187.1.7
Routing entry for 11.187.1.7/32
Known via "ospf 1", distance 110, metric 20, type extern 2, forward metric 1
Last update from 11.187.7.162 on GigabitEthernet1/11, 3w6d ago
Routing Descriptor Blocks:
11.187.7.178, from 11.187.7.217, 3w6d ago, via GigabitEthernet1/18
Route metric is 20, traffic share count is 1
* 11.187.7.162, from 11.187.7.209, 3w6d ago, via GigabitEthernet1/11
Route metric is 20, traffic share count is 1

OR via Choice 2

SwitchA#sh ip route vrf CDE_Outer 11.187.1.7
Routing entry for 11.187.1.7/32
Known via "static", distance 1, metric 0
Redistributing via ospf 3
Routing Descriptor Blocks:
* 11.187.7.148
Route metric is 0, traffic share count is 1

[Seb Rupik · Accepted solution]

Hi there,
Since SVI Vlan3371 is in the deafult routing table, if a packet arrives from 11.187.7.128 /29 destined for 11.187.1.7, since you have two equal cost paths available then it's next hop will either be 11.187.7.162 or 11.187.7.178.

cheers,
Seb.

[Jon Marshall · Accepted solution]

The packet arrives on a interface that is not part of a VRF so the global routing table will be used to forward the packet. 

Jon