This document answers frequently asked questions about Data Link Switching Plus (DLSw+) and Multilayer Switch Feature Card (MSFC).
Q. Is DLSw+ supported on MSFC/MSFC2, and what feature set is required to run DLSw+ on MSFC/MSFC2 in the Catalyst 6500?
A. Yes, DLSw+ is supported on MSFC/MSFC2. The minimum feature set required for MSFC/MSFC2 is IP Plus. For MSFC, the image name should read c6msfc-is-mz.xxx, and for MSFC2, the image should read c6msfc2-is-mz.xxx, where xxx is the Cisco IOS® Software Release. It is highly recommended that you use the latest release that is available to registered users.
Q. What is the minimum Cisco IOS Software Release that supports DLSw+ on the MSFC, and what caveats of which should I be aware, when running DLSw+ on the MSFC/MSFC2 in general?
A. The minimum Cisco IOS Software Release that supports DLSw+ on the MSFC and MSFC2 is 12.1(1)E and 12.1(2)E, respectively. However, due to some well known caveats, listed in the next bullets, it is important that the latest Cisco IOS Software Release is used.
CSCds55205—DLSw+ does not work with MSFC2. Integrated in 12.1(04.04)EC and 12.1(04.04)E.
CSCds70377—DLSw+ Ethernet Redundancy does not work on MSFC2. Integrated in 12.1(05.06)EC and 12.1(05.06)E.
CSCdp94760—DLSw+ Ethernet Redundancy does not load balance between peers. Integrated in 12.1(03)DC, 12.1(03)DB, 012.001(002.002), 12.1(02.02)T, 12.1(02.02)PI, and 12.1(02.03)E.
CSCdt14719—DLSw+ Ethernet Redundancy needs more modularity to better support multiple instances. Integrated in 12.2(03.04)PB, 12.1(06.05)E, 12.2(00.18)S, 12.1(06.05)EC, 12.2(00.10)PI01, 12.1(06.05)AA, 012.002(000.010), 12.2(00.09)T, and 012.001(006.005).
CSCdp93599—Request to add DLSw Ethernet Redundancy in the MSFC platform. Integrated in 12.1(01.05)E01.
CSCds41679—DLSw on MSFC sends wrong lf bits in CANUREACH (CUR). Integrated in 12.1(05.06)E, 12.1(06)E01, 12.1(05.06)EC, 12.1(05.03)T, and 012.001(005.003).
CSCdx20546—Possible packet encapsulation error in DLSw. Integrated in 12.1(11.05)EC, 12.2(09)S, 12.1(11.05)E, 12.1(11b)E02, and 12.1(08b)E10.
These Cisco bug IDs apply to DLSw Fast-Sequenced Transport (FST) in general:
A. The DLSw+ Ethernet Redundancy feature was introduced in Cisco IOS Software Release 12.0(5)T to provide redundancy and load balancing between multiple DLSw+ peers in an Ethernet environment. The feature also enables DLSw+ to support multiple DLSw+ routers on the same transparent bridged domain that can reach the same MAC address in a switched environment. DLSw+ Ethernet Redundancy was designed for the remote branch office side, not the central site hub-end. For more information on DLSw+ Ethernet Redundancy, refer to these documents:
A. Yes, DLSw+ Ethernet Redundancy is supported on the MSFC. Refer to Question 2 for information about bugs of which you should be aware. The minimum feature IP Plus is also required. (Refer to Question 1.)
A. Yes. Because the Catalyst 6500 does not support Token Ring, and Ethernet does not support Routing Information Field (RIF), DLSw+ has no way to determine whether end-station device MAC addresses are sourced locally or remotely. This can result in problems with bridge loops, which can cause a Systems Network Architecture (SNA) session disruption. DLSw+ is also process intensive; to run any significant volume of DLSw traffic on the MSFC is counterproductive to the real purpose of a Layer 3 switch. For example, you have greater granularity in router CPU power and scalability with a 7200 Network Processing Engine/Network Service Engine (NPE/NSE) to handle the workload and failover redundancy requirements, than with the MSFC.
Note: You can run DLSw+ on an external router with an Inter-Switch Link (ISL) sub-interface instead of running DLSw+ on the MSFC.
Q. Are there any performance figures to enable me to compare MSFC against other platforms for DLSw+ with TCP?
A. Yes, there is a white paper on DLSw+ TCP Performance that shows the percentage of the CPU that is utilized on various Cisco Router platforms as a function of data frames transported between two DLSw+ TCP peers.
A. Yes, FST is supported on the MSFC from Cisco IOS Software Release 12.1(8.5)E2 (refer to Cisco bug ID CSCdu47920 ( registered customers only) ), and from Cisco IOS Software Release 12.1(9.5)E for MSFC2 (refer to Cisco bug ID CSCdu47927 ( registered customers only) ).
A. DLSw+ works on an MSFC; however, no official tests have been performed with two MSFC2s in the same chassis. DLSw+ code has no way to identify that the two MSFC2s are in the same chassis, and has no supporting code for anything like this. More importantly, DLSw+ Ethernet Redundancy is designed for the remote end, not for the central site. Ethernet Redundancy still assumes a Token Ring is on the central location.
A. Consider this topology:
Note: MSFC2 and Router2 are DLSw+ Ethernet Redundancy peers.
Note: That topology was assembled in a lab environment with Ethernet media used for WAN connections. In reality, this is done with serial connections.! hostname Router1 ! ! source-bridge ring-group 100 dlsw local-peer peer-id 172.17.240.68 promiscuous ! ! interface Ethernet0/0 description ip address 172.17.240.68 255.255.255.0 ip address 172.17.240.68 255.255.255.0 ip directed-broadcast half-duplex ! ! interface TokenRing0/0 no ip address ip directed-broadcast no keepalive ring-speed 16 source-bridge 2 1 100 source-bridge spanning !! hostname MSFC2 ! dlsw local-peer peer-id 172.17.240.4 dlsw remote-peer 0 tcp 172.17.240.68 dlsw transparent switch-support ! ! interface Vlan1 ip address 172.17.240.4 255.255.255.0 ! interface Vlan2 mac-address 0222.0222.0222 no ip address dlsw transparent redundancy-enable 9999.9999.9999 !--- This router is Slave. dlsw transparent map local-mac 0220.0220.0220 remote-mac aaaa.aaaa.aaaa neighbor 0211.0211.0211 !--- Note: The previous two lines of code appear on one line. !! hostname Router2 ! ! source-bridge ring-group 100 dlsw local-peer peer-id 172.17.240.40 dlsw remote-peer 0 tcp 172.17.240.68 dlsw transparent switch-support ! ! interface Ethernet0 description ip address 172.17.240.40 255.255.255.0 ip address 172.17.240.40 255.255.255.0 media-type 10BaseT ! interface Ethernet1 mac-address 0211.0211.0211 no ip address keepalive 30 media-type 10BaseT dlsw transparent redundancy-enable 9999.9999.9999 master-priority 10 !--- This router is Master. dlsw transparent map local-mac 0201.0201.0201 remote-mac aaaa.aaaa.aaaa neighbor 0222.0222.0222 !--- Note: The previous two lines of code appear on one line. !MSFC2# show dlsw peer Peers: state pkts_rx pkts_tx type drops ckts TCP uptime TCP 172.17.240.68 CONNECT 8 5 conf 0 0 0 00:02:00 Total number of connected peers: 1 Total number of connections: 1 MSFC2# show dlsw transparent neighbor Interface Vlan2 4044.4044.4044 SELF Slave 4088.4088.4088 Connected MASTER. !--- Note: All MAC addresses show non-canonical format (Token Ring format). MSFC2# show dlsw transparent map Interface Vlan2 LOCAL Mac REMOTE MAC BACKUP --------- ---------- ------ 4004.4004.4004 5555.5555.5555 4088.4088.4088 STATIC 4080.4080.4080 5555.5555.5555 4088.4088.4088 DYNAMIC(Passive)
Note: Because all MAC addresses in the previous command are in non-canonical format, local MAC 4004.4004.4004 (0220.0220.0220) maps to the host MAC address 5555.5555.5555 and the backup 4088.4088.4088 (0211.0211.0211), which is the other redundant DLSw peer (Router2).
Note: The Client is configured to connect to 0201.0201.0201 in Router2 and not the host MAC address of 5555.5555.5555. (Alternatively, it can point to MSFC2 0220.0220.0220.) When Router2 recognizes the connection request to 0201.0201.0201 (which is 4080.4080.4080 after bitswap) Router2 maps this request to the host MAC address 5555.5555.5555. This is shown in this configured command on Router2:dlsw transparent map local-mac 0201.0201.0201 remote-mac aaaa.aaaa.aaaa neighbor 0222.0222.0222 !--- Note: The previous two lines of code appear on one line. !--- aaaa.aaaa.aaaa is the host MAC address (5555.5555.5555) !--- in canonical format.
Note: All MAC addresses in this command are in canonical format (Ethernet format).MSFC2# show dlsw transparent cache Interface Vlan2 Circuit Cache local addr(lsap) remote addr(dsap) state Owner Router1 has two peer connections: Router1# show dlsw peer Peers: state pkts_rx pkts_tx type drops ckts TCP uptime TCP 172.17.240.40 CONNECT 9 7 prom 0 1 0 00:00:17 TCP 172.17.240.4 CONNECT 2 2 prom 0 0 0 00:00:16 Total number of connected peers: 2 Total number of connections: 2 Router1# show dlsw reach DLSw Local MAC address reachability cache list Mac Addr status Loc. port rif 1000.5af2.f083 FOUND LOCAL TokenRing0/0 06C0.0021.0640 5555.5555.5555 FOUND LOCAL TokenRing0/0 0640.0641.0020 DLSw Remote MAC address reachability cache list Mac Addr status Loc. peer 0800.0800.0800 FOUND REMOTE 172.17.240.40(2065) !--- 0800.0800.0800 is 1000.1000.1000 after bitswap. Router1# show dlsw circuit detail Index local addr(lsap) remote addr(dsap) state uptime 4194304017 5555.5555.5555(08) 0800.0800.0800(08) CONNECTED 00:00:15 PCEP: 617BB7C4 UCEP: 61AAB1BC Port:To0/0 peer 172.17.240.40(2065) Flow-Control-Tx CW:20, Permitted:39; Rx CW:20, Granted:19; Op: Repeat Congestion: Low(02), Flow Op: Half: 0/0 Reset 0/0 RIF = 0610.0641.0020 Bytes: 18/129 Info-frames: 1/1 XID-frames: 1/2 UInfo-frames: 0/0 Total number of circuits connected: 1 Router2# show dlsw transparent neighbor Interface Eth1 4088.4088.4088 SELF Master 4044.4044.4044 Rcvd Master-Accepted VALID Router2# show dlsw transparent neighbor Interface Et1 LOCAL Mac REMOTE MAC BACKUP --------- ---------- ------ 4080.4080.4080 5555.5555.5555 4044.4044.4044 STATIC 4004.4004.4004 5555.5555.5555 4044.4044.4044 DYNAMIC(Passive)
Router2 is the MASTER and have the transparent cache:Router2# show dlsw transparent cache Interface Et1 Circuit Cache local addr(lsap) remote addr(dsap) state Owner 0800.0800.0800(08) 5555.5555.5555(08) POSITIVE SELF Total number of circuits in the Cache: 1 Router2# show dlsw reach DLSw Local MAC address reachability cache list Mac Addr status Loc. port rif 0800.0800.0800 FOUND LOCAL Ethernet1 --no rif-- 1000.5af2.f59e FOUND LOCAL TokenRing0 06B0.0011.0640 DLSw Remote MAC address reachability cache list Mac Addr status Loc. peer 1000.5af2.f083 FOUND REMOTE 172.17.240.68(2065) 5555.5555.5555 FOUND REMOTE 172.17.240.68(2065) max-lf(8144) Router2# show dlsw peer Peers: state pkts_rx pkts_tx type drops ckts TCP uptime TCP 172.17.240.68 CONNECT 19 17 conf 0 1 0 00:03:42 Total number of connected peers: 1 Total number of connections: 1 Router2# show dlsw circuit detail Index local addr(lsap) remote addr(dsap) state uptime 1006632966 0800.0800.0800(08) 5555.5555.5555(08) CONNECTED 00:03:41 PCEP: 617880DC UCEP: 619DEFD8 Port:Et1 peer 172.17.240.68(2065) Flow-Control-Tx CW:20, Permitted:19; Rx CW:20, Granted:39; Op: Repeat Congestion: Low(02), Flow Op: Half: 0/0 Reset 0/0 RIF = --no rif-- Bytes: 129/18 Info-frames: 1/1 XID-frames: 2/1 UInfo-frames: 0/0 Total number of circuits connected: 1
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