This article helps to understand why integrated routing and bridging (IRB) cannot be configured as a routing interface in the Virtual Private LAN Service (VPLS) setup on ACX series routers, with the help of an example.
Consider the following topology:
irb.100 (1.1.1.1) irb.100(1.1.1.2) +-------+ +------+ | | | | | R1 +-----------------------------+ R2 | | | VPLS | | +---+---+ +---+--+ | | | | | | | | | | | | +---+---+ +--+---+ | | | | | CE1 | | CE2 | | | | | +-------+ +------+
In the above topology:
R1 and R2 are directly connected.
A VPLS session exists between R1 to R2, providing connectivity between CE1 and CE2.
irb.100 is configured as the routing interface in the VPLS instance.
Configuration on R1
R1# show interfaces irb.100 family inet { address 1.1.1.1/30; } R1# show routing-instances VPLS instance-type vpls; vlan-id 600; interface ge-1/0/3.100; routing-interface irb.100; >>>> IRB is configured as the routing interface. route-distinguisher 100:100; vrf-target target:1:1; protocols { vpls { site-range 10; no-tunnel-services; site R2 { site-identifier 2; } } Physical interface: irb, Enabled, Physical link is Up Interface index: 128, SNMP ifIndex: 501 Type: Ethernet, Link-level type: Ethernet, MTU: 1514 Device flags : Present Running Interface flags: SNMP-Traps Link type : Full-Duplex Link flags : None Current address: ec:13:db:ec:b8:a0, Hardware address: ec:13:db:ec:b8:a0 Last flapped : Never Input packets : 0 Output packets: 0 Logical interface irb.100 (Index 328) (SNMP ifIndex 573) Flags: Up SNMP-Traps 0x0 Encapsulation: ENET2 Bandwidth: 1000mbps Routing Instance: VPLS Bridging Domain: None Input packets : 0 Output packets: 0 Protocol inet, MTU: 1500 Max nh cache: 20000, New hold nh limit: 20000, Curr nh cnt: 0, Curr new hold cnt: 0, NH drop cnt: 0 Flags: Sendbcast-pkt-to-re Protocol multiservice, MTU: 1500 R1> show vpls connections Layer-2 VPN connections: Legend for connection status (St) EI -- encapsulation invalid NC -- interface encapsulation not CCC/TCC/VPLS EM -- encapsulation mismatch WE -- interface and instance encaps not same VC-Dn -- Virtual circuit down NP -- interface hardware not present CM -- control-word mismatch -> -- only outbound connection is up CN -- circuit not provisioned <- -- only inbound connection is up OR -- out of range Up -- operational OL -- no outgoing label Dn -- down LD -- local site signaled down CF -- call admission control failure RD -- remote site signaled down SC -- local and remote site ID collision LN -- local site not designated LM -- local site ID not minimum designated RN -- remote site not designated RM -- remote site ID not minimum designated XX -- unknown connection status IL -- no incoming label MM -- MTU mismatch MI -- Mesh-Group ID not available BK -- Backup connection ST -- Standby connection PF -- Profile parse failure PB -- Profile busy RS -- remote site standby SN -- Static Neighbor LB -- Local site not best-site RB -- Remote site not best-site VM -- VLAN ID mismatch HS -- Hot-standby Connection Legend for interface status Up -- operational Dn -- down Instance: VPLS Edge protection: Not-Primary Local site: R2 (2) connection-site Type St Time last up # Up trans 1 rmt Up Sep 19 10:52:17 2019 1 Remote PE: 172.23.218.65, Negotiated control-word: No Incoming label: 262145, Outgoing label: 262146 Local interface: lsi.1048656, Status: Up, Encapsulation: VPLS Description: Intf - vpls VPLS local site 2 remote site 1 Flow Label Transmit: No, Flow Label Receive: No R1# run ping 1.1.1.1 rapid count 10 PING 1.1.1.1 (1.1.1.1): 56 data bytes .......... --- 1.1.1.1 ping statistics --- 10 packets transmitted, 0 packets received, 100% packet loss
This is a product limitation. Ping to the IRB interface will not work because it is host-bound traffic.
When a ping to the IRB interface comes, the packets will have the destination MAC address of the IRB interface and will enter VPLS. The internal MAC table will match the address and the forwarding logic will try to route them. Since routing is not possible/enabled in VPLS, the packets get discarded.
Dec 09 2024 - Added platform acx5448 and acx710 to the unsupported platforms