In an previous post Advertising IPs In EVPN Route Type 2, I described use cases for advertising IP addresses in EVPN route type 2. Host ARP and host mobility I already covered so today we will focus on host routing.
To be able to show this scenario, I have added another server (SERVER-2) and will be using the topology below:
There is already existing configuration for VLAN 10 (L2 VNI) and for VLAN 100 (L3 VNI) which is shown below:
vrf context Tenant1
vni 10001
rd auto
address-family ipv4 unicast
route-target both auto
route-target both auto evpn
!
interface Vlan10
no shutdown
vrf member Tenant1
ip address 198.51.100.1/24
fabric forwarding mode anycast-gateway
!
interface Vlan100
no shutdown
mtu 9216
vrf member Tenant1
ip forward
To get SERVER-2 connected the following is needed:
- Configure VLAN 20 and map it to L2 VNI (VNI 10002).
- Make the L2 VNI a member of the NVE.
- SVI for VLAN 20.
- Configure port towards SERVER-2 in VLAN 20.
This is shown below:
vlan 20
vn-segment 10002
!
interface nve1
member vni 10002
ingress-replication protocol bgp
!
interface Vlan20
no shutdown
vrf member Tenant1
ip address 10.0.0.1/24
fabric forwarding mode anycast-gateway
!
interface Ethernet1/3
switchport access vlan 20
Now let’s try to ping 10.0.0.1 from SERVER-2:
ping 10.0.0.1 PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data. 64 bytes from 10.0.0.1: icmp_seq=2 ttl=255 time=1.16 ms 64 bytes from 10.0.0.1: icmp_seq=3 ttl=255 time=1.17 ms
That is working. Let’s see if we can ping SERVER-1:
ping 198.51.100.11 PING 198.51.100.11 (198.51.100.11) 56(84) bytes of data. 64 bytes from 198.51.100.11: icmp_seq=1 ttl=62 time=5.07 ms 64 bytes from 198.51.100.11: icmp_seq=2 ttl=62 time=5.58 ms
That is now working as well. In a future post I will describe more on symmetric IRB and do a detailed packet walk, but for now let’s focus on the control plane. How is routing provided between LEAF-2 where SERVER-2 is connected and LEAF-1 where SERVER-1 is connected? LEAF-2 advertises two route type 2 routes with information about SERVER-2. One route is the MAC address only and the other route contains both the MAC and IP as can be seen below:
Leaf2# show bgp l2vpn evpn 0050.56ad.f48d
BGP routing table information for VRF default, address family L2VPN EVPN
Route Distinguisher: 192.0.2.4:32787 (L2VNI 10002)
BGP routing table entry for [2]:[0]:[0]:[48]:[0050.56ad.f48d]:[0]:[0.0.0.0]/216, version 971
Paths: (1 available, best #1)
Flags: (0x000102) (high32 00000000) on xmit-list, is not in l2rib/evpn
Advertised path-id 1
Path type: local, path is valid, is best path, no labeled nexthop
AS-Path: NONE, path locally originated
203.0.113.2 (metric 0) from 0.0.0.0 (192.0.2.4)
Origin IGP, MED not set, localpref 100, weight 32768
Received label 10002
Extcommunity: RT:65000:10002 ENCAP:8
Path-id 1 advertised to peers:
192.0.2.11 192.0.2.12
BGP routing table entry for [2]:[0]:[0]:[48]:[0050.56ad.f48d]:[32]:[10.0.0.22]/272, version 972
Paths: (1 available, best #1)
Flags: (0x000102) (high32 00000000) on xmit-list, is not in l2rib/evpn
Advertised path-id 1
Path type: local, path is valid, is best path, no labeled nexthop
AS-Path: NONE, path locally originated
203.0.113.2 (metric 0) from 0.0.0.0 (192.0.2.4)
Origin IGP, MED not set, localpref 100, weight 32768
Received label 10002 10001
Extcommunity: RT:65000:10001 RT:65000:10002 ENCAP:8 Router MAC:00ad.f3bb.1b08
Path-id 1 advertised to peers:
192.0.2.11 192.0.2.12
It is the second route which contains MAC and IP that can be used to provide host routing. As the name implies, host routing only works with /32 and /128 routes depending on IP protocol version. You can’t advertise a /24 in this manner, for example. That would require route type 5. The second route has route targets containing both the L2 VNI (65000:10002) and the L3 VNI (65000:10001). LEAF-1 has a L3 VNI that is importing routes that have a route target of 65000:10001. If we look at LEAF-1, we can first see the route that was originated by LEAF-2 with an RD of 192.0.2.4:32787 and then the imported route which has the RD of 192.0.2.3:3:
Leaf1# show bgp l2vpn evpn 0050.56ad.f48d
BGP routing table information for VRF default, address family L2VPN EVPN
Route Distinguisher: 192.0.2.4:32787
BGP routing table entry for [2]:[0]:[0]:[48]:[0050.56ad.f48d]:[32]:[10.0.0.22]/272, version 1276
Paths: (2 available, best #2)
Flags: (0x000202) (high32 00000000) on xmit-list, is not in l2rib/evpn, is not in HW
Path type: internal, path is valid, not best reason: Neighbor Address, no labeled nexthop
AS-Path: NONE, path sourced internal to AS
203.0.113.2 (metric 81) from 192.0.2.12 (192.0.2.2)
Origin IGP, MED not set, localpref 100, weight 0
Received label 10002 10001
Extcommunity: RT:65000:10001 RT:65000:10002 ENCAP:8 Router MAC:00ad.f3bb.1b08
Originator: 192.0.2.4 Cluster list: 192.0.2.2
Advertised path-id 1
Path type: internal, path is valid, is best path, no labeled nexthop
Imported to 2 destination(s)
Imported paths list: Tenant1 L3-10001
AS-Path: NONE, path sourced internal to AS
203.0.113.2 (metric 81) from 192.0.2.11 (192.0.2.1)
Origin IGP, MED not set, localpref 100, weight 0
Received label 10002 10001
Extcommunity: RT:65000:10001 RT:65000:10002 ENCAP:8 Router MAC:00ad.f3bb.1b08
Originator: 192.0.2.4 Cluster list: 192.0.2.1
Path-id 1 not advertised to any peer
Route Distinguisher: 192.0.2.3:3 (L3VNI 10001)
BGP routing table entry for [2]:[0]:[0]:[48]:[0050.56ad.f48d]:[32]:[10.0.0.22]/272, version 1277
Paths: (1 available, best #1)
Flags: (0x000202) (high32 00000000) on xmit-list, is not in l2rib/evpn, is not in HW
Advertised path-id 1
Path type: internal, path is valid, is best path, no labeled nexthop
Imported from 192.0.2.4:32787:[2]:[0]:[0]:[48]:[0050.56ad.f48d]:[32]:[10.0.0.22]/272
AS-Path: NONE, path sourced internal to AS
203.0.113.2 (metric 81) from 192.0.2.11 (192.0.2.1)
Origin IGP, MED not set, localpref 100, weight 0
Received label 10002 10001
Extcommunity: RT:65000:10001 RT:65000:10002 ENCAP:8 Router MAC:00ad.f3bb.1b08
Originator: 192.0.2.4 Cluster list: 192.0.2.1
Path-id 1 not advertised to any peer
The 10.0.0.22/32 route gets imported into VRF Tenant-1:
Leaf1# show ip route vrf Tenant1
IP Route Table for VRF "Tenant1"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>
10.0.0.22/32, ubest/mbest: 1/0
*via 203.0.113.2%default, [200/0], 00:34:14, bgp-65000, internal, tag 65000, segid: 10001 tunnelid: 0xcb007102 encap: VXLAN
By advertising MAC and IP in route type 2, routing between hosts gets enabled automatically. There are some scenarios with silent/shy hosts where this doesn’t work. I will cover that in a future post. That’s all for this one!