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Layer3 MC-LAG Deployment

This enables NetOps to configure dual homing of Server host upstreaming to 2 Leaf switches through MC-LAG protocol over Layer 3 interfaces thus offering protection to Server Hosted applications

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L3 MC LAG Functions:

  • MC-LAG involves two or more switches (peers) connected to each other and to the network.
  • The peers work together to appear as a single logical switch to the connected devices.
  • MC LAG enables load balancing and high availability by allowing traffic to flow through both peers.

Layer 3 Extension:

  • In a Layer 3 MC-LAG setup, the MLAG peers are capable of performing Layer 3
  • routing functions.
  • This means they can route IP traffic between different subnets, extending the MC-LAG benefits to Layer 3.

Benefits:

  • High Availability: If one of the MLAG peers fails, the other can seamlessly take over, ensuring network continuity.
  • Load Balancing: Both peers actively participate in handling traffic, distributing the load and preventing bottlenecks.
  • Scalability: Layer 3 MC LAG allows for efficient scaling of IP subnets and routing capabilities.

Use Cases:

  • Layer 3 MC-LAG is often employed in data center environments and large enterprise networks where high availability and efficient routing are crucial.
  • It allows multiple switches (Leaf-Spine nodes) to act as a single logical entity for routing purposes, enhancing high availability and load balancing.

YAML Template 

Inventory:
  SSpines: 0
  Spines: 2
  Leafs: 4
  Tors: 0
Connectivity:
  SSpine: []
  Spine:
    - switchId: 1
      switchName: "Spine-1"
      ipAddress: "x.x.x.11"
      ASN: 1001
      Credentials:
        user: "admin"
        password: "admin"
      mclag: null
      Links:
        - link: "S1_Ethernet0 | L1_Ethernet48"
          staticLink: true
          properties: null
        - link: "S1_Ethernet4 | L2_Ethernet48"
          staticLink: true
          properties: null
        - link: "S1_Ethernet8 | L3_Ethernet48"
          staticLink: true
          properties: null
        - link: "S1_Ethernet12 | L4_Ethernet48"
          staticLink: true
          properties: null
    - switchId: 2
      switchName: "Spine-2"
      ipAddress: "x.x.x.12"
      ASN: 1002
      Credentials:
        user: "admin"
        password: "admin"
      mclag: null
      Links:
        - link: "S2_Ethernet0 | L1_Ethernet52"
          staticLink: true
          properties: null
        - link: "S2_Ethernet4 | L2_Ethernet52"
          staticLink: true
          properties: null
        - link: "S2_Ethernet8 | L3_Ethernet52"
          staticLink: true
          properties: null
        - link: "S2_Ethernet12 | L4_Ethernet52"
          staticLink: true
          properties: null
  Leaf:
    - switchId: 1
      switchName: "Leaf-1"
      ipAddress: "x.x.x.13"
      ASN: 2001
      Credentials:
        user: "admin"
        password: "admin"
      mclag:
        enabled: true
        peer: "L2"
        keepalive_vlan: 10
        isoverl3: true
      Links:
        - link: "L1_Ethernet48 | S1_Ethernet0"
          staticLink: true
          properties: null
        - link: "L1_Ethernet52 | S2_Ethernet0"
          staticLink: true
          properties: null  
        - link: "L1_Ethernet64 |  L2_Ethernet64"
          staticLink: true
          properties: null               
        - link: "L1_Ethernet56 |  L2_Ethernet56"
          staticLink: true
          properties:
            mode: "MC-LAG"
        - link: "L1_Ethernet0 |  H1_Ethernet0"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 200
        - link: "L1_Ethernet4 |  H2_Ethernet0"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 201
    - switchId: 2
      switchName: "Leaf-2"
      ipAddress: "x.x.x.14"
      ASN: 2001
      Credentials:
        user: "admin"
        password: "admin"
      mclag:
        enabled: true
        peer: "L1"
        keepalive_vlan: 10
        isoverl3: true
      Links:
        - link: "L2_Ethernet48 | S1_Ethernet4"
          staticLink: true
          properties: null
        - link: "L2_Ethernet52 | S2_Ethernet4"
          staticLink: true
          properties: null
        - link: "L2_Ethernet64 |  L1_Ethernet64"
          staticLink: true
          properties: null           
        - link: "L2_Ethernet56 | L1_Ethernet56"
          staticLink: true
          properties:
            mode: "MC-LAG"
        - link: "L2_Ethernet0 |  H1_Ethernet1"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 200
        - link: "L2_Ethernet4 |  H2_Ethernet1"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 201
    - switchId: 3
      switchName: "Leaf-3"
      ipAddress: "x.x.x.15"
      ASN: 2002
      Credentials:
        user: "admin"
        password: "admin"
      mclag:
        enabled: true
        peer: "L4"
        keepalive_vlan: 10
        isoverl3: true
      Links:
        - link: "L3_Ethernet48 | S1_Ethernet8"
          staticLink: true
          properties: null
        - link: "L3_Ethernet52 | S2_Ethernet8"
          staticLink: true
          properties: null
        - link: "L3_Ethernet60 |  L4_Ethernet60"
          staticLink: true
          properties: null           
        - link: "L3_Ethernet56 | L4_Ethernet56"
          staticLink: true
          properties:
            mode: "MC-LAG"
        - link: "L3_Ethernet0 |  H3_Ethernet0"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 200
        - link: "L3_Ethernet4 |  H4_Ethernet0"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 201
    - switchId: 4
      switchName: "Leaf-4"
      ipAddress: "x.x.x.16"
      ASN: 2002
      Credentials:
        user: "admin"
        password: "admin"
      mclag:
        enabled: true
        peer: "L3"
        keepalive_vlan: 10
        isoverl3: true
      Links:
        - link: "L4_Ethernet48 | S1_Ethernet12"
          staticLink: true
          properties: null
        - link: "L4_Ethernet52 | S2_Ethernet12"
          staticLink: true
          properties: null
        - link: "L4_Ethernet60 |  L3_Ethernet60"
          staticLink: true
          properties: null            
        - link: "L4_Ethernet56 | L3_Ethernet56"
          staticLink: true
          properties:
            mode: "MC-LAG"
        - link: "L4_Ethernet0 |  H3_Ethernet1"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 200
        - link: "L4_Ethernet4 |  H4_Ethernet1"
          staticLink: true
          properties:
            mode: "L3-V4"
            mc_po_group: 201
  Tor: []
BGP:
  BGP_U: false
  ND_RA: 30
PhysicalIfCfg:
  FEC: "Off"
  MTU: 9000
  AdminStatus: "Up"
ASN:
  SSpine: "10000-20000"
  Spine: "21000-50000"
  Leaf: "51000-60000"
  Tor: "61000-70000"
IPv4Pool:
  Loopback: "10.10.10.0/24"
  LeafSpine: "40.0.0.0/24"
  LeafTor: "39.0.0.0/24"
  Host: "49.0.0.0/24"
IPv6Pool:
  LeafSpine: null
  LeafTor: null
  Host: null
NTP:
  server: "x.x.x.10"
  timezone: "Asia/Kolkata"
SYSLOG:
  server: "x.x.x.10"
SNMP:
  trapserver: "x.x.x.10"
Parameters:
  hosts_per_l3_subnet: 10

Configure, Validate & Verify through UI

img

Running config on Sonic Switch 

router-id 10.10.10.3
ntp add x.x.x.10
clock timezone Asia/Kolkata
syslog add x.x.x.10
snmp-server trap modify 2 x.x.x.10 port 161 vrf None community Public
hostname Leaf-1
ip protocol bgp route-map RM_SET_SRC
!
route-map FMCLI_IPV6_NH_GLOBAL permit 1
on-match next
set ipv6 next-hop prefer-global
!
route-map RM_SET_SRC permit 10
set src 10.10.10.3
!
interface port-channel 200
mtu 9000
ip address 49.0.0.0/27
!
interface port-channel 201
mtu 9000
ip address 49.0.0.32/27
!
interface port-channel 999
mtu 9000
ip address 192.168.0.0/31
!
interface ethernet Ethernet0
no shutdown
mtu 9000
channel-group 200 mode active
forward-error-correction none
!
interface ethernet Ethernet4
no shutdown
mtu 9000
channel-group 201 mode active
forward-error-correction none
!
interface ethernet Ethernet48
no shutdown
mtu 9000
ip address 40.0.0.1/31
forward-error-correction none
!
interface ethernet Ethernet52
no shutdown
mtu 9000
ip address 40.0.0.9/31
forward-error-correction none
!
interface ethernet Ethernet56
no shutdown
mtu 9000
channel-group 999 mode active
forward-error-correction none
!
interface ethernet Ethernet64
no shutdown
mtu 9000
ip address 40.0.0.16/31
forward-error-correction none
!
interface loopback 1
ip address 10.10.10.3/32
!
router bgp 2001
neighbor 40.0.0.0 remote-as 1001
neighbor 40.0.0.17 remote-as 2001
neighbor 40.0.0.8 remote-as 1002
neighbor 40.0.0.0 capability extended-nexthop
neighbor 40.0.0.17 capability extended-nexthop
neighbor 40.0.0.8 capability extended-nexthop
bgp bestpath as-path multipath-relax
no bgp ebgp-requires-policy
address-family ipv4 unicast
neighbor 40.0.0.0 allowas-in 1
neighbor 40.0.0.17 allowas-in 1
neighbor 40.0.0.8 allowas-in 1
network 40.0.0.0/31
network 40.0.0.16/31
network 40.0.0.8/31
redistribute connected
redistribute static
!
address-family ipv6 unicast
redistribute connected
redistribute static
!
!
mlag domain-id 1
peer-address 192.168.0.1
peer-link port-channel 999
src-address 192.168.0.0
member port-channel 200
member port-channel 201

router-id 10.10.10.4
ntp add x.x.x.10
clock timezone Asia/Kolkata
syslog add x.x.x.10
snmp-server trap modify 2 x.x.x.10 port 161 vrf None community Public
hostname Leaf-2
ip protocol bgp route-map RM_SET_SRC
!
route-map FMCLI_IPV6_NH_GLOBAL permit 1
on-match next
set ipv6 next-hop prefer-global
!
route-map RM_SET_SRC permit 10
set src 10.10.10.4
!
interface port-channel 200
mtu 9000
ip address 49.0.0.0/27
!
interface port-channel 201
mtu 9000
ip address 49.0.0.32/27
!
interface port-channel 999
mtu 9000
ip address 192.168.0.1/31
!
interface ethernet Ethernet0
no shutdown
mtu 9000
channel-group 200 mode active
forward-error-correction none
!
interface ethernet Ethernet4
no shutdown
mtu 9000
channel-group 201 mode active
forward-error-correction none
!
interface ethernet Ethernet48
no shutdown
mtu 9000
ip address 40.0.0.3/31
forward-error-correction none
!
interface ethernet Ethernet52
no shutdown
mtu 9000
ip address 40.0.0.11/31
forward-error-correction none
!
interface ethernet Ethernet56
no shutdown
mtu 9000
channel-group 999 mode active
forward-error-correction none
!
interface ethernet Ethernet64
no shutdown
mtu 9000
ip address 40.0.0.17/31
forward-error-correction none
!
interface loopback 1
ip address 10.10.10.4/32
!
router bgp 2001
neighbor 40.0.0.10 remote-as 1002
neighbor 40.0.0.16 remote-as 2001
neighbor 40.0.0.2 remote-as 1001
neighbor 40.0.0.10 capability extended-nexthop
neighbor 40.0.0.16 capability extended-nexthop
neighbor 40.0.0.2 capability extended-nexthop
bgp bestpath as-path multipath-relax
no bgp ebgp-requires-policy
address-family ipv4 unicast
neighbor 40.0.0.10 allowas-in 1
neighbor 40.0.0.16 allowas-in 1
neighbor 40.0.0.2 allowas-in 1
network 40.0.0.10/31
network 40.0.0.16/31
network 40.0.0.2/31
redistribute connected
redistribute static
!
address-family ipv6 unicast
redistribute connected
redistribute static
!
!
mlag domain-id 1
peer-address 192.168.0.0
peer-link port-channel 999
src-address 192.168.0.1
member port-channel 200
member port-channel 201

router-id 10.10.10.6
ntp add x.x.x.10
clock timezone Asia/Kolkata
syslog add x.x.x.10
snmp-server trap modify 2 x.x.x.10 port 161 vrf None community Public
hostname Leaf-3
ip protocol bgp route-map RM_SET_SRC
!
route-map FMCLI_IPV6_NH_GLOBAL permit 1
on-match next
set ipv6 next-hop prefer-global
!
route-map RM_SET_SRC permit 10
set src 10.10.10.6
!
interface port-channel 200
mtu 9000
ip address 49.0.0.64/27
!
interface port-channel 201
mtu 9000
ip address 49.0.0.96/27
!
interface port-channel 999
mtu 9000
ip address 192.168.0.2/31
!
interface ethernet Ethernet0
no shutdown
mtu 9000
channel-group 200 mode active
forward-error-correction none
!
interface ethernet Ethernet4
no shutdown
mtu 9000
channel-group 201 mode active
forward-error-correction none
!
interface ethernet Ethernet48
no shutdown
mtu 9000
ip address 40.0.0.5/31
forward-error-correction none
!
interface ethernet Ethernet52
no shutdown
mtu 9000
ip address 40.0.0.13/31
forward-error-correction none
!
interface ethernet Ethernet56
no shutdown
mtu 9000
channel-group 999 mode active
forward-error-correction none
!
interface ethernet Ethernet60
no shutdown
mtu 9000
ip address 40.0.0.22/31
forward-error-correction none
!
interface loopback 1
ip address 10.10.10.6/32
!
router bgp 2002
neighbor 40.0.0.12 remote-as 1002
neighbor 40.0.0.23 remote-as 2002
neighbor 40.0.0.4 remote-as 1001
neighbor 40.0.0.12 capability extended-nexthop
neighbor 40.0.0.23 capability extended-nexthop
neighbor 40.0.0.4 capability extended-nexthop
bgp bestpath as-path multipath-relax
no bgp ebgp-requires-policy
address-family ipv4 unicast
neighbor 40.0.0.12 allowas-in 1
neighbor 40.0.0.23 allowas-in 1
neighbor 40.0.0.4 allowas-in 1
network 40.0.0.12/31
network 40.0.0.22/31
network 40.0.0.4/31
redistribute connected
redistribute static
!
address-family ipv6 unicast
redistribute connected
redistribute static
!
!
mlag domain-id 1
peer-address 192.168.0.3
peer-link port-channel 999
src-address 192.168.0.2
member port-channel 200
member port-channel 201

router-id 10.10.10.7
ntp add x.x.x.10
clock timezone Asia/Kolkata
syslog add x.x.x.10
snmp-server trap modify 2 x.x.x.10 port 161 vrf None community Public
hostname Leaf-4
ip protocol bgp route-map RM_SET_SRC
!
route-map FMCLI_IPV6_NH_GLOBAL permit 1
on-match next
set ipv6 next-hop prefer-global
!
route-map RM_SET_SRC permit 10
set src 10.10.10.7
!
interface port-channel 200
mtu 9000
ip address 49.0.0.64/27
!
interface port-channel 201
mtu 9000
ip address 49.0.0.96/27
!
interface port-channel 999
mtu 9000
ip address 192.168.0.3/31
!
interface ethernet Ethernet0
no shutdown
mtu 9000
channel-group 200 mode active
forward-error-correction none
!
interface ethernet Ethernet4
no shutdown
mtu 9000
channel-group 201 mode active
forward-error-correction none
!
interface ethernet Ethernet48
no shutdown
mtu 9000
ip address 40.0.0.7/31
forward-error-correction none
!
interface ethernet Ethernet52
no shutdown
mtu 9000
ip address 40.0.0.15/31
forward-error-correction none
!
interface ethernet Ethernet56
no shutdown
mtu 9000
channel-group 999 mode active
forward-error-correction none
!
interface ethernet Ethernet60
no shutdown
mtu 9000
ip address 40.0.0.23/31
forward-error-correction none
!
interface loopback 1
ip address 10.10.10.7/32
!
router bgp 2002
neighbor 40.0.0.14 remote-as 1002
neighbor 40.0.0.22 remote-as 2002
neighbor 40.0.0.6 remote-as 1001
neighbor 40.0.0.14 capability extended-nexthop
neighbor 40.0.0.22 capability extended-nexthop
neighbor 40.0.0.6 capability extended-nexthop
bgp bestpath as-path multipath-relax
no bgp ebgp-requires-policy
address-family ipv4 unicast
neighbor 40.0.0.14 allowas-in 1
neighbor 40.0.0.22 allowas-in 1
neighbor 40.0.0.6 allowas-in 1
network 40.0.0.14/31
network 40.0.0.22/31
network 40.0.0.6/31
redistribute connected
redistribute static
!
address-family ipv6 unicast
redistribute connected
redistribute static
!
!
mlag domain-id 1
peer-address 192.168.0.2
peer-link port-channel 999
src-address 192.168.0.3
member port-channel 200
member port-channel 201