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This chapter describes how to configure Internetwork Packet Exchange (IPX) Multilayer Switching (MLS) on the Catalyst 6000 family switches.
This chapter contains these sections:
These sections provide an overview of MLS and describe how MLS works:
IPX MLS provides high-performance hardware-based Layer 3 switching for Catalyst 6000 family LAN switches. IPX MLS switches unicast IPX data packet flows between networks using advanced application-specific integrated circuit (ASIC) switching hardware, offloading processor-intensive packet routing from network routers.
The packet forwarding function is moved onto Layer 3 switches whenever a switched path exists between two hosts. Packets that do not have a switched path to reach their destinations are still forwarded by routers. Standard routing protocols, such as IPX Routing Information Protocol (RIP), Enhanced Interior Gateway Protocol (EIGRP), and NetWare Link Services Protocol (NLSP), are used for route determination.
Layer 3 protocols, such as IP and IPX, are connectionless---they deliver every packet independently of every other packet. However, actual network traffic consists of many end-to-end conversations, or flows, between users or applications.
A flow is a unidirectional sequence of packets between a particular source and destination that share the same protocol and network-layer information. Communication from a client to a server and from the server to the client are separate flows.
Flows are based only on Layer 3 addresses, which allow IPX traffic from multiple users or applications to a particular destination to be carried on a single flow if only the destination IPX address is used to identify a flow.
The Policy Feature Card (PFC) maintains a Layer 3 switching table (MLS cache) for the Layer 3-switched flows. The cache includes entries for traffic statistics that are updated in tandem with the switching of packets. After the MLS cache is created, packets identified as belonging to an existing flow can be Layer 3 switched based on the cached information. The MLS cache maintains flow information for all active flows.
An IPX MLS cache entry is created for the initial packet of each flow. Upon receipt of a packet that does not match any flow currently in the MLS cache, a new IPX MLS entry is created.
The state and identity of the flow are maintained while packet traffic is active; when traffic for a flow ceases, the entry ages out. You can configure the aging time for IPX MLS entries kept in the MLS cache. If an entry is not used for the specified period of time, the entry ages out and statistics for that flow can be exported to a flow collector application.
The maximum MLS cache size is 128K entries. However, an MLS cache larger than 32K entries increases the probability that a flow will not be switched by the PFC and will get forwarded to the router.
The flow mask mode for IPX MLS is destination mode. The PFC maintains one IPX MLS entry for each destination IPX address (network and node). All flows to a given destination IPX address use this IPX MLS entry. This mode is always used.
When a packet is Layer 3 switched from a source host to a destination host, the switch (PFC) performs a packet rewrite, based on information learned from the router (MSFC) and stored in the MLS cache.
If Host A and Host B are on different VLANs and Host A sends a packet to the MSFC to be routed to Host B, the PFC recognizes that the packet was sent to the MAC address of the MSFC. The PFC checks the MLS cache and finds the entry matching the flow in question.
When the PFC receives the packet, it is (conceptually) formatted as follows:
| Frame Header | Encap | IPX Header | Payload | |||||
|---|---|---|---|---|---|---|---|---|
Destination | Source | Length | Checksum/ IPX Length/ Transport Control n1 | Packet Type | Destination Net/Node/ Socket | Source Net/Node/ Socket | Data | Pad/FCS |
MSFC MAC | Host A MAC |
|
| Host B IPX | Host A IPX |
|
| |
| 1Transport Control is incremented by 1 each time this packet is routed. If this number is greater than the maximum (the default is 16), the packet is dropped. |
The PFC rewrites the Layer 2 frame header, changing the destination MAC address to the MAC address of Host B and the source MAC address to the MAC address of the MSFC (these MAC addresses are stored in the IPX MLS cache entry for this flow). The Layer 3 IPX addresses remain the same. The PFC rewrites the switched Layer 3 packets so that they appear to have been routed by a router.
The PFC forwards the rewritten packet to Host B's VLAN (the destination VLAN is saved in the IPX MLS cache entry), and Host B receives the packet.
After the PFC performs the packet rewrite, the packet is (conceptually) formatted as follows:
| Frame Header | Encap | IPX Header | Payload | |||||
|---|---|---|---|---|---|---|---|---|
Destination | Source | Length | Checksum/ IPX Length/ Transport Control n+1 | Packet Type | Destination Net/Node/ Socket | Source Net/Node/ Socket | Data | Pad/FCS |
Host B MAC | MSFC MAC |
|
| Host B IPX | Host A IPX |
|
| |
Figure 5-1 shows a conceptual IPX MLS network topology. In this example, Host A is on the Sales VLAN (IPX address 01.Aa), Host B is on the Marketing VLAN (IPX address 03.Bb), and Host C is on the Engineering VLAN (IPX address 02.Cc).
When Host A initiates a file transfer to Host B, an IPX MLS entry for this flow is created (this entry is the first item in the table shown in Figure 5-1). The PFC stores the MAC addresses of the MSFC and Host B in the IPX MLS entry when the MSFC forwards the first packet from Host A through the switch to Host B. The PFC uses this information to rewrite subsequent packets from Host A to Host B.
Similarly, a separate IPX MLS entry is created in the MLS cache for the traffic from Host A to Host C, and for the traffic from Host C to Host A. The destination VLAN is stored as part of each IPX MLS entry so that the correct VLAN identifier is used when encapsulating traffic on trunk links.
Table 5-1 shows the default IPX MLS configuration.
| Feature | Default Value |
|---|---|
IPX MLS enable state | Enabled |
IPX MLS aging time | 256 seconds |
These sections describe configuration guidelines that apply when configuring IPX MLS:
Other IOS software features affect IPX MLS as follows:
In IPX, the two end points of communication negotiate the maximum transmission unit (MTU) to be used. MTU size is limited by media type.
These sections describe how to configure the MSFC for IPX MLS. Depending upon your configuration, you might not have to perform all the steps in the procedure.
After you perform the steps in this section to configure the router, see the "Configuring IPX MLS on the Switch" section.
IPX MLS is enabled globally by default, but you can disable or enable IPX MLS on a specified interface.
To disable IPX MLS on a specific router interface, perform this task in interface configuration mode:
| Task | Command |
|---|---|
Disable IPX MLS on a router interface. | Router(config-if)# no mls ipx |
This example shows how to disable IPX MLS on a router interface:
Router(config-if)# no mls ipx Router(config-if)#
To enable IPX MLS on a specific router interface, perform this task in interface configuration mode:
| Task | Command |
|---|---|
Enable IPX MLS on a router interface. | Router(config-if)# mls ipx |
This example shows how to enable IPX MLS on a router interface:
Router(config-if)# mls ipx Router(config-if)#
Table 5-2 describes IPX MLS-related debug commands that you can use to troubleshoot IPX MLS problems on the router.
| Command | Description |
[no] debug l3 events | Displays Layer 3 manager-related events. |
[no] debug l3 packets | Displays Layer 3 manager packets. |
[no] debug l3 global | Displays bugtrace of ipx global purge events. |
[no] debug l3 all | Turns on all Layer 3 manager debugging messages. |
Table 5-3 describes IPX MLS-related debug commands that you can use to troubleshoot IPX MLS problems when using the MSFC as an external router for a Catalyst 5000 family switch.
| Command | Description |
|---|---|
[no] debug mls ipx | Turns on IPX-related events for MLS, including route purging and changes of access lists and flow masks. |
[no] debug mls locator | Identifies which switch is switching a particular flow by using MLS explorer packets. |
[no] debug mls all | Turns on all MLS debugging events. |
[no] mls locate ipx ipx_addr [source_net] | Displays information about all the switches that are currently shortcutting for the specified IPX flow(s). |
Table 5-4 describes the Serial Control Protocol (SCP)-related debug commands to troubleshoot the SCP that runs over the Ethernet out-of-band channel (EOBC).
| Command | Description |
[no] debug scp async | Displays trace for async data in and out of the SCP system. |
[no] debug scp data | Displays packet data trace. |
[no] debug scp errors | Displays errors and warnings in SCP. |
[no] debug scp packets | Displays packet data in and out of the SCP system. |
[no] debug scp timeouts | Reports timeouts. |
[no] debug scp all | Turns on all SCP debugging messages. |
IPX MLS is disabled by default on Catalyst 6000 family switches.
These sections describe how to configure IPX MLS on the switch:
The IPX MLS aging time applies to all IPX MLS cache entries. Any IPX MLS entry that has not been used for agingtime seconds is aged out. The default is 256 seconds.
You can configure the aging time in the range of 8 to 2024 seconds in 8-second increments. Any aging-time value that is not a multiple of 8 seconds is adjusted to the closest multiple of 8 seconds. For example, a value of 65 is adjusted to 64 and a value of 127 is adjusted to 128.
Other events might cause IPX MLS entries to be purged, such as routing changes or a change in link state (PFC link is down).
To specify the IPX MLS aging time, perform this task in privileged mode:
| Task | Command |
|---|---|
Specify the IPX MLS aging time for an MLS cache entry. | set mls agingtime ipx [agingtime] |
This example shows how to specify the IPX MLS aging time:
Console> (enable) set mls agingtime ipx 512 IPX Multilayer switching aging time set to 512 Console> (enable)
The show cam msfc command displays the content-addressable memory (CAM) entries associated with a specific MAC address. If the MAC address belongs to an MSFC, an "R" is appended to the MAC address.
If you specify a VLAN number, only those CAM entries corresponding to that VLAN number are displayed. If a VLAN is not specified, entries for all VLANs are displayed.
To display CAM entries on the switch, perform this task:
| Task | Command |
|---|---|
Display CAM entries by MAC-VLAN address. | show cam msfc [vlan | mod1] |
| 1The mod keyword specifies the module number of the MSFC; either 15 (if the MSFC is installed on the supervisor engine in slot 1) or 16 (if the MSFC is installed on the supervisor engine in slot 2). |
This example shows how to display the CAM entries for a specified MSFC:
Console> show cam msfc 15 VLAN Destination MAC Destination Ports or VCs Xtag Status ---- ------------------- ------------------------------ ---- ---- 400 00-d0-d3-9c-e3-f4R 15/1 1 410 00-d0-d3-9c-e3-f4R 15/1 1 24 00-d0-d3-9c-e3-f4R 15/1 1 27 00-d0-d3-9c-e3-f4R 15/1 1 22 00-d0-d3-9c-e3-f4R 15/1 1 28 00-d0-d3-9c-e3-f4R 15/1 1 Total Matching CAM Entries Displayed = 6 Console> (enable)
The show mls ipx command displays IPX MLS information and MSFC-specific information.
To display IPX MLS information on the switch, perform this task:
| Task | Command |
|---|---|
Display general IPX MLS information and router-specific information for all MSFCs. | show mls ipx [mod1] |
| 1The mod keyword specifies the module number of the MSFC; either 15 (if the MSFC is installed on the supervisor engine in slot 1) or 16 (if the MSFC is installed on the supervisor engine in slot 2). |
This example shows how to display IPX MLS information on the switch:
Console> (enable) show mls ipx
IPX Multilayer switching aging time = 256 seconds
IPX flow mask is Destination flow
IPX max hop is 15
Active IPX MLS entries = 356
IPX MSFC ID Module XTAG MAC Vlans
--------------- ------ ---- ----------------- ----------------
22.1.0.56 15 1 00-10-07-38-29-18 2,3,4,5,6,
7,8,9,10,11,
12,13,14,15,16,
17,18,19,20,66,
77
00-d0-d3-9c-e3-f4 25
00-10-07-38-29-18 26,111
00-d0-d3-9c-e3-f4 112
22.1.0.58 16 2 00-10-07-38-22-22 2,3,4,5,6,
7,8,9,10,11,
12,13,14,15,16,
17,18,19,20
00-d0-d3-33-17-8c 25
00-10-07-38-22-22 26,66,77,88,99,
111
00-d0-d3-33-17-8c 112
Console> (enable)
These sections describe how to display IPX MLS cache entries on the switch:
To display all IPX MLS entries on the switch, perform this task in privileged mode:
| Task | Command |
|---|---|
Display all IPX MLS entries. | show mls entry ipx |
This example shows how to display all IPX MLS entries on the switch:
Console> (enable) show mls entry ipx Destination-IPX Destination-Mac Vlan EDst ESrc Port Stat-Pkts Stat-Bytes Uptime Age ------------------------- ----------------- ---- ---- ---- ----- ---------- ----------- -------- -------- MSFC 22.1.0.56 (Module 15): 11.0000.0000.2B10 00-00-00-00-2b-10 11 ARPA ARPA - 6977 320942 00:14:04 00:00:00 11.0000.0000.A810 00-00-00-00-a8-10 11 ARPA ARPA - 3488 160448 00:14:04 00:00:00 11.0000.0000.3210 00-00-00-00-32-10 11 ARPA ARPA - 6979 321034 00:14:04 00:00:00 11.0000.0000.B110 00-00-00-00-b1-10 11 ARPA ARPA - 3489 160494 00:14:04 00:00:00 11.0000.0000.1910 00-00-00-00-19-10 11 ARPA ARPA - 6981 321126 00:14:04 00:00:00 11.0000.0000.9A10 00-00-00-00-9a-10 11 ARPA ARPA - 3490 160540 00:14:04 00:00:00 11.0000.0000.0010 00-00-00-00-00-10 11 ARPA ARPA 3/11 6983 321218 00:14:04 00:00:00 11.0000.0000.8310 00-00-00-00-83-10 11 ARPA ARPA - 3491 160586 00:14:04 00:00:00 10.0000.0000.0109 00-00-00-00-01-09 10 ARPA ARPA 3/10 85455 3930930 00:14:05 00:00:00 11.0000.0000.4F10 00-00-00-00-4f-10 11 ARPA ARPA - 6986 321356 00:14:05 00:00:00 11.0000.0000.CC10 00-00-00-00-cc-10 11 ARPA ARPA - 3492 160632 00:14:05 00:00:00 11.0000.0000.5610 00-00-00-00-56-10 11 ARPA ARPA - 6987 321402 00:14:05 00:00:00 Console> (enable)
To display IPX MLS entries for a specific destination IPX address, perform this task in privileged mode:
| Task | Command |
|---|---|
Display IPX MLS entries for a specific destination IPX address (net_address.node_address). | show mls entry ipx destination ipx_addr |
This example shows how to display IPX MLS entries for a specific destination IPX address:
Console> (enable) show mls entry ipx destination 3E.0010.298a.0c00 Destination IPX Source IPX net Destination Mac Vlan Port ------------------------- -------------- ----------------- ---- ----- MSFC 22.1.0.56 (Module 15): 3E.0010.298a.0c00 13 00-00-00-00-00-09 26 4/7 Console> (enable)
To display IPX MLS entries for a specific MSFC, perform this task in privileged mode:
| Task | Command |
|---|---|
Display IPX MLS entries for a specific MSFC. | show mls entry ipx mod1 |
| 1The mod keyword specifies the module number of the MSFC; either 15 (if the MSFC is installed on the supervisor engine in slot 1) or 16 (if the MSFC is installed on the supervisor engine in slot 2). |
This example shows how to display IPX MLS entries for a specific MSFC:
Console> (enable) show mls entry ipx 15 Destination-IPX Destination-Mac Vlan EDst ESrc Port Stat-Pkts Stat-Bytes Uptime Age ------------------------- ----------------- ---- ---- ---- ----- ---------- ----------- -------- -------- MSFC 22.1.0.56 (Module 15): 11.0000.0000.2B10 00-00-00-00-2b-10 11 ARPA ARPA - 7869 361974 00:15:52 00:00:00 11.0000.0000.A810 00-00-00-00-a8-10 11 ARPA ARPA - 3934 180964 00:15:52 00:00:00 11.0000.0000.3210 00-00-00-00-32-10 11 ARPA ARPA - 7871 362066 00:15:52 00:00:00 11.0000.0000.B110 00-00-00-00-b1-10 11 ARPA ARPA - 3935 181010 00:15:52 00:00:00 11.0000.0000.1910 00-00-00-00-19-10 11 ARPA ARPA - 7873 362158 00:15:52 00:00:00 11.0000.0000.9A10 00-00-00-00-9a-10 11 ARPA ARPA - 3936 181056 00:15:52 00:00:00 11.0000.0000.0010 00-00-00-00-00-10 11 ARPA ARPA 3/11 7875 362250 00:15:52 00:00:00 11.0000.0000.8310 00-00-00-00-83-10 11 ARPA ARPA - 3937 181102 00:15:52 00:00:00 10.0000.0000.0109 00-00-00-00-01-09 10 ARPA ARPA 3/10 96364 4432744 00:15:52 00:00:00 11.0000.0000.4F10 00-00-00-00-4f-10 11 ARPA ARPA - 7877 362342 00:15:53 00:00:00 11.0000.0000.CC10 00-00-00-00-cc-10 11 ARPA ARPA - 3938 181148 00:15:53 00:00:00 11.0000.0000.5610 00-00-00-00-56-10 11 ARPA ARPA - 7879 362434 00:15:53 00:00:00 11.0000.0000.D510 00-00-00-00-d5-10 11 ARPA ARPA - 3939 181194 00:15:53 00:00:00 11.0000.0000.7D10 00-00-00-00-7d-10 11 ARPA ARPA - 3940 181240 00:15:53 00:00:00 11.0000.0000.FE10 00-00-00-00-fe-10 11 ARPA ARPA - 3941 181286 00:15:53 00:00:00 11.0000.0000.6410 00-00-00-00-64-10 11 ARPA ARPA - 7883 362618 00:15:53 00:00:00 11.0000.0000.E710 00-00-00-00-e7-10 11 ARPA ARPA - 3941 181286 00:15:53 00:00:00 11.0000.0000.6010 00-00-00-00-60-10 11 ARPA ARPA - 7885 362710 00:15:53 00:00:00 11.0000.0000.E310 00-00-00-00-e3-10 11 ARPA ARPA - 3942 181332 00:15:53 00:00:00 11.0000.0000.7910 00-00-00-00-79-10 11 ARPA ARPA - 3943 181378 00:15:54 00:00:00 Console> (enable)
The clear mls entry ipx command removes specific IPX MLS cache entries on the switch. The destination and source keywords specify the source and destination IPX addresses. The all keyword clears all MLS entries.
To clear IPX MLS entries, perform one of these tasks in privileged mode:
| Task | Command |
|---|---|
| clear mls entry ipx [destination ipx_addr] [source ipx_net] |
| clear mls entry ipx [mod] all |
This example shows how to clear IPX MLS entries with destination IPX address 1.0002.00e0.fefc.6000:
Console> (enable) clear mls entry ipx destination 1.0002.00e0.fefc.6000 MLS IPX entry cleared. Console> (enable)
The show mls statistics entry command displays IPX MLS statistics for MLS cache entries. Specify the destination IPX address and source IPX address to see specific IPX MLS cache entries.
To display statistics for IPX MLS cache entries, perform this task in privileged mode:
| Task | Command |
|---|---|
Display statistics for IPX MLS cache entries. If you do not specify an IPX MLS cache entry, all statistics are shown. | show mls statistics entry ipx [destination ipx_addr] [source ipx_net] |
This example shows how to display statistics for a particular IPX MLS cache entry:
Console> (enable) show mls statistics entry ipx destination 1.0002.00e0.fefc.6000 Destination IPX Source IPX net Stat-Pkts Stat-Bytes ---------------------- --------------- --------- ---------- MSFC 22.1.0.56 (Module 15): 1.00e0.fefc.6000 1.0003 11 521 Console> (enable)
The clear mls statistics command clears the MLS (IP and IPX) statistics on the switch.
To clear MLS statistics on the switch, perform this task in privileged mode:
| Task | Command |
|---|---|
Clear MLS statistics on the switch. | clear mls statistics |
This example shows how to clear MLS statistics on the switch:
Console> (enable) clear mls statistics All mls statistics cleared. Console> (enable)
Posted: Tue Feb 22 10:49:27 PST 2000
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