Thursday, December 5, 2013

Basic Multicast Overlay Transport Virtualization


After the basic unicast OTV bring up its time to move ahead and bring up OTV using multicast.

Some of you may have guessed why we go in for a multicast OTV solution. Multicast by nature performs one to many, hence, when we have multiple ED's located at various DC's, it would make sense to have multicast OTV [this again is based on the assumption that the transport connecting your DC's together supports multicast] 

As before, lets just dive into the details related to topology and configuration. As we go along I will try my best to explain in brief why we need each of the configurations.

The topology is I will be using for multicast OTV is very much the same as the one I used for unicast OTV:





However, now, the ED's and the CORE will have multicast specific configurations on them.
ED1:

ip multicast-routing distributed

ip igmp snooping querier version 3
ip igmp snooping querier

otv site bridge-domain 150
otv site-identifier 0000.0000.0002    ! the site-identifier

interface GigabitEthernet0/0/0
 description "ACCESS / INTERNAL INTERFACE"
 no shutdown
 negotiation auto
 service instance 14 ethernet
  encapsulation dot1q 14
  bridge-domain 14
 !
 service instance 150 ethernet
  encapsulation dot1q 150
  bridge-domain 150

interface GigabitEthernet0/0/1
 no ip address
 no shutdown
 negotiation auto

router ospf 14
 router-id 14.14.14.1

interface GigabitEthernet0/0/1.14
 description "JOIN INTERFACE"
 encapsulation dot1Q 14
 ip address 10.1.14.2 255.255.255.0
 ip pim passive
 ip igmp version 3
 ip ospf 14 area 14

interface Overlay150
 no ip address
 no shutdown                               ! added by me
 otv control-group 232.1.14.1
 otv data-group 232.14.1.0/24
 otv join-interface GigabitEthernet0/0/1.14
 service instance 14 ethernet
  encapsulation dot1q 14
  bridge-domain 14

CORE:

ip multicast-routing distributed

router ospf 14
 router-id 14.14.14.2

interface Loopback14
 ip address 14.14.14.14 255.255.255.255
 ip ospf 14 area 14

ip pim rp-address 14.14.14.14

interface GigabitEthernet0/0/1
 no ip address
 no shutdown
 negotiation auto

interface GigabitEthernet0/0/1.14
 description "CORE INTERFACE CONNECTED TO ED1"
 encapsulation dot1Q 14
 ip address 10.1.14.1 255.255.255.0
 ip pim sparse-mode
 ip igmp version 3
 ip ospf 14 area 14

interface GigabitEthernet0/0/0
 no ip address
 no shutdown
 negotiation auto

interface GigabitEthernet0/0/0.14
 description "CORE INTERFACE CONNECTED TO ED2"
 encapsulation dot1Q 14
 ip address 10.2.14.1 255.255.255.0
 ip pim sparse-mode
 ip igmp version 3
 ip ospf 14 area 14

ED2:

ip multicast-routing distributed

ip igmp snooping querier version 3
ip igmp snooping querier

otv site bridge-domain 151
otv site-identifier 0000.0000.0003

interface GigabitEthernet0/0/1
 description "ACCESS / INTERNAL INTERFACE"
 no shutdown
 negotiation auto
 service instance 14 ethernet
  encapsulation dot1q 14
  bridge-domain 14
 !
 service instance 151 ethernet
  encapsulation dot1q 151
  bridge-domain 151       

interface GigabitEthernet0/0/0
 no ip address
 no shutdown
 negotiation auto

router ospf 14
 router-id 14.14.14.3

interface GigabitEthernet0/0/0.14
 description "JOIN INTERFACE"
 encapsulation dot1Q 14
 ip address 10.2.14.2 255.255.255.0
 ip pim passive
 ip igmp version 3
 ip ospf 14 area 14

interface Overlay150
 no ip address
 no shutdown                               ! added by me
 otv control-group 232.1.14.1
 otv data-group 232.14.1.0/24
 otv join-interface GigabitEthernet0/0/0.14
 service instance 14 ethernet
  encapsulation dot1q 14
  bridge-domain 14
Some inputs before we go into verification:
  1. Its good to keep in mind that whenever we configure 'interface overlay <num>' it is by default in shutdown state. Hence, I have added the 'no shutdown' in the configuration myself
  2. The 'ip multicast-routing distributed' - will enable multicast routing on the routers
  3. 'otv control-group' - ASM group in the core used for the OTV Control Plane [this group address should be same between all the ED's across the DC's for the MAC updates]
  4. 'otv data-group' - This is for sending multicast traffic from one DC to the other, related to SSM [we will be discussing this in the coming updates]
Another important point to note here is that the multicast addresses used in the control-group and data-group should be provided by the service-provider of the transport linking your DC's.

The verification as with unicast OTV follows the same process of checking the "show otv" details [the router used is ED2, but one can use either ED1 / ED2]:

ED2#show otv
Overlay Interface Overlay150
 VPN name                 : None
 VPN ID                   : 1
 State                    : UP
 AED Capable              : Yes
 IPv4 control group       : 232.1.14.1
 Mcast data group range(s): 232.14.1.0/24
 Join interface(s)        : GigabitEthernet0/0/0.14
 Join IPv4 address        : 10.2.14.2
 Tunnel interface(s)      : Tunnel0
 Encapsulation format     : GRE/IPv4
 Site Bridge-Domain       : 151
 Capability               : Multicast-reachable
 Is Adjacency Server      : No
 Adj Server Configured    : No
 Prim/Sec Adj Svr(s)      : None

ED2#

Checking the ping traffic flow between VM1 and VM2:

[root@vm-aries-cel ~]# ping 172.16.11.10 -c 10
PING 172.16.11.10 (172.16.11.10) 56(84) bytes of data.
64 bytes from 172.16.11.10: icmp_seq=0 ttl=64 time=0.491 ms
64 bytes from 172.16.11.10: icmp_seq=1 ttl=64 time=0.546 ms
64 bytes from 172.16.11.10: icmp_seq=2 ttl=64 time=0.651 ms
64 bytes from 172.16.11.10: icmp_seq=3 ttl=64 time=0.546 ms
64 bytes from 172.16.11.10: icmp_seq=4 ttl=64 time=0.723 ms
64 bytes from 172.16.11.10: icmp_seq=5 ttl=64 time=0.564 ms
64 bytes from 172.16.11.10: icmp_seq=6 ttl=64 time=0.635 ms
64 bytes from 172.16.11.10: icmp_seq=7 ttl=64 time=0.547 ms
64 bytes from 172.16.11.10: icmp_seq=8 ttl=64 time=0.529 ms
64 bytes from 172.16.11.10: icmp_seq=9 ttl=64 time=0.546 ms

--- 172.16.11.10 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9000ms
rtt min/avg/max/mdev = 0.491/0.577/0.723/0.072 ms, pipe 2
[root@vm-aries-cel ~]# 

 MAC updates related to both VM1 and VM2:

 The below MAC addresses are learned from the other ED's [ED1 in our case]

ED2#show otv isis rib mac 

Tag Overlay150:
 MAC  local rib for Overlay150 (Total 1)
  L2 Topology ID        Mac Address             
  14                    000C.295E.EA91 --> MAC address VM1
    [50/1] via 10.1.14.2(Overlay150), LSP[3/2]
ED2#

 The below MAC addresses will be sent to the other ED's [these MAC addresses will be sent to ED1 from ED2]:

ED2#show otv isis rib redistribution mac

Tag Overlay150:
 MAC redistribution local rib for Overlay150 (Total 3)
  L2 Topology ID        Mac Address             
  14                    000C.297E.8CD5
    State: Up/Best/Advertised Metric: 1
  14                    000C.2980.1494 --> MAC address VM2
    State: Up/Best/Advertised Metric: 1
  14                    0050.56BF.4129
    State: Up/Best/Advertised Metric: 1
ED2#

 The below command is the one using which OTV does ARP suppression:

ED2#show otv arp-nd-cache 
Overlay150 ARP/ND L3->L2 Address Mapping Cache
BD     MAC            Layer-3 Address  Age (HH:MM:SS) Local/Remote
14     000c.295e.ea91 172.16.11.20     00:01:24       Remote

ED2#

Finally the packet is routed out using the below table, wherein we see that '000c.295e.ea91' is destined to ED1:

ED2#show otv route 

Codes: BD - Bridge-Domain, AD - Admin-Distance,
       SI - Service Instance, * - Backup Route

OTV Unicast MAC Routing Table for Overlay150

 Inst VLAN BD     MAC Address    AD    Owner  Next Hops(s)
----------------------------------------------------------
 0    14   14     000c.295e.ea91 50    ISIS   ED1
 0    14   14     000c.297e.8cd5 40    BD Eng Gi0/0/1:SI14
 0    14   14     000c.2980.1494 40    BD Eng Gi0/0/1:SI14
 0    14   14     0050.56bf.4129 40    BD Eng Gi0/0/1:SI14

4 unicast routes displayed in Overlay150

----------------------------------------------------------
4 Total Unicast Routes Displayed

ED2# 

This ends our basic discussion on how one can bring up multicast OTV over a multicast-core.

 The posts that follow will build on these basics [either unicast / multicast OTV] and proceed further towards multihoming / IPSec / HSRP / vMotion and others.

NOTE: All the above tests were done using the recently released XE-3.11 release

Hope you found this post informative.


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