In the example above, PC-A wants to communicate with PC-B. They are in different VLANs so the traffic will be routed via the RSM (default gateway for the PCs). The first packet will be sent by PC-A and routed by the RSM towards PC-B; a shortcut, PC-A --> PC-B, will be created and all subsequent packets will be Layer 3 switched by the MLS-SE (Supervisor=NFFC). PC-A#ping 12.12.12.12 !-- pinging PC-B
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 12.12.12.12, timeout is 2 seconds: !!!!! SUCcess rate is 100 percent (5/5), round-trip min/avg/max = 1/3/4 ms
On the switch:
switch-MLS-SE (enable) show mls entry Destination IP Source IP PRot DstPrt SrcPrt Destination Mac Vlan Port --------------- --------------- ---- ------ ------ ----------------- ---- ----- MLS-RP 11.11.11.1: 11.11.11.11 12.12.12.12 ICMP - - 00-d0-58-43-9f-60 11 6/11 !-- As in the note above we have two shortcuts A->B and B->A 12.12.12.12 11.11.11.11 ICMP - - 00-00-0c-07-ac-01 12 6/12 switch-MLS-SE (enable)
switch-MLS-SE (enable) show mls Multilayer switching enabled !-- By default, MLS is enabled on the switch Multilayer switching aging time = 256 seconds Multilayer switching fast aging time = 0 seconds, packet threshold = 0 Current flow mask is Destination flow Configured flow mask is Destination flow Total packets switched = 8 !-- Five echos and five replies were sent; the first echo and reply went !-- through the RSM and subsequent were Layer 3 switched, which gives us a total of !-- eight Layer 3 switched packets and two shortcuts.
Active shortcuts = 2 Netflow Data EXPort disabled Total packets exported = 0
MLS-RP IP MLS-RP ID XTAG MLS-RP MAC-Vlans ---------------- ------------ ---- --------------------------------- 11.11.11.1 00100b108800 2 00-10-0b-10-88-00 11-12 switch-MLS-SE (enable)
switch-MLS-SE (enable) show mls statistics rp Total packets switched = 8 Active shortcuts = 2 Total packets exported= 0
Total switched MLS-RP IP MLS-RP ID packets bytes --------------- ------------ ---------- ------------ 11.11.11.1 00100b108800 8 944 switch-MLS-SE (enable)
RSM-MLS-RP#sho mls rp multilayer switching is globally enabled mls id is 0010.0b10.8800 mls ip address 11.11.11.1 !-- IP address of MLS-RP mls flow mask is destination-ip number of domains configured for mls 1
vlan domain name: sales current flow mask: destination-ip current sequence number: 3150688457 current/maximum retry count: 0/10 current domain state: no-change current/next global purge: false/false current/next purge count: 0/0 domain uptime: 1d00h keepalive timer expires in 8 seconds retry timer not running change timer not running
1 management interface(s) currently defined: vlan 11 on Vlan11
2 mac-vlan(s) configured for multi-layer switching:
mac 0010.0b10.8800 vlan id(s) 11 12 !-- VLANs, interfaces participating in MLS
router currently aware of following 1 switch(es): switch id 0050.d133.2bff !-- MAC address of the MLS-SE
On the switch, MLS is enabled by default. There is no need to specify the MLS-RP IP address if it is the RSM. However, for an external router acting as the MLS-RP, we need to configure the switch with this IP address by using the following command:
set mls include
To configure the router, follow the steps below:
Enable MLS IP in global configuration:
Router(config)#mls rp ip
Assign a VTP domain on one MLS interface. The show vtp domain command on the switch provides the VTP domain name; our example is "sales":
Router(config-if)#mls rp vtp-domain sales
Enable MLS on the interface so that it can participate in the shortcut process:
Router(config-if)#mls rp ip
Specify a router interface as a management interface, allowing for the MLS-SE and MLS-RP to communicate using a multicast protocol (MLSP):
Router(config-if)#mls rp management-interface
MLS-RP (RSM) Current configuration:
!
version 11.3
! hostname RSM-MLS-RP ! ! mls rp ip ! ! interface Vlan11 ip address 11.11.11.1 255.255.255.0 mls rp vtp-domain sales mls rp management-interface mls rp ip ! interface Vlan12 ip address 12.12.12.1 255.255.255.0 mls rp vtp-domain sales mls rp ip ! ip classless ! ! ! line con 0 line aux 0 line vty 0 4 login ! end
