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S7C7
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Frame forwarding and rewrite function is moved to hardware and layer 3 switching ... Add interfaces to same VLAN Trunking protocol (VTP) domain as switch ... – PowerPoint PPT presentation
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Title: S7C7
1
S7C7 Multilayer Switching
- Design and Configuration
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Multilayer Switching Overview
- Higher performance level
- First packet though is routed
- Rest of packet stream is switched
- Frame forwarding and rewrite function is moved to
hardware and layer 3 switching takes over task
formerly done by routers - MLS uses RSM and the engine
- Any switching path on the RSM will work
- NetFlow switching is different
3
What MLS NEEDS We dont have
- 2926G, 5000, 6000 with supervisor engine software
gt4.1(1) - Cisco IOS gt11.3
- Supervisor Engine III or G
- Route Switch Feature Card (RSFC)
4
MLS Components
- Multilayer Switching Switch Engine (MLS-SE)
- An NFFC residing on a Supervisor Engine III card
- Multilayer Switching Route Processor (MLS-RP)
- An RSM, RSFC, MSFC, or external router
- Multilayer Switching Protocol (MLSP)
- Operates between MLS-SE and MLS-RP
- Advertises routing changes, VLANS, and MAC
addresses
5
MLS-RP Advertisements
- Hello messages sent every 15 seconds to all
switches in network - MAC addresses used by MLS-RP on all interfaces
participating in MLS - Access List information
- Route additions and deletions
- Processed only by layer 3 switches others pass
messages downstream - Uses Cisco Group Management Protocol (CGMP)
multicast address
6
MLS Caching
- Switch receives frame - looks at destination MAC
- Recognizes address as MLS-RP address because of
hello message information - Checks MLS cache to determine is MLS flow is
already established - For initial packet, forwards frame to route
processor creates candidate entry in cache - Route processor consults routing table
- If it finds entry, constructs a new Layer 3
header enters MAC address of destination host
or next-hope route processor as destination MAC
address - Route processor forwards frame back to MLS-SE
7
MLS Cache Explanation
- Xtags enable switch to know frame came from same
route processor for same flow - Subsequent frames follow first
- MLS-SE must see both sides of flow from source to
destination to perform layer 3 switching - Switch will then rewrite layer 3 frame header and
rewrite switches layer 3 packets so they appear
to have been routed by route processor - Switch forwards rewritten frame to destination
MAC address - When traffic for flow ceases, the entry ages out
(remains in cache for only 5 seconds)
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Stopping MLS
- Any command that forces router to examine packet
disables MLS - IP tcp header-compression
- No IP routing
- IP security
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Steps to Configure MLS
- Enable MLSP
- Assign VLAN ID to route processor interface
- Add interfaces to same VLAN Trunking protocol
(VTP) domain as switch - Enable MLS on every interface
- Configure MLS Management interface
- Verify MLS on MLS-RP
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Displaying VTP Domain Information
- Show mls rp vtp-domain DOMAINNAME
- Name of vtp domain
- Statistical information for each vtp domain
- Number of management interfaces defined for
MLS-RP - Number of VLANS in domain and ID of each
- MLS-Ses which router or RSM knows
- MAC address of each switch in domain
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Verifying MLS-RP
- Show mls rp
- Globally enabled or disabled
- MLS ID for MLS-RP
- MLS IP address for MLS-RP
- MLS flow mask
- Name of VTP domain
- Statistical information for VTP domain
- Management interfaces defined for MLS-RP
- VLANs configured for MLS
- VLAN ID for MAC address
- MLS-Ses to which RSM or router is connected
- MAC address of each switch
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Flow Masks
- Used by MLS-SE to determine how packets are
compared to MLS entries in the MLS cache - Based on access lists configured on MLS router
- Learned through MLSP messages
- Supports only one flow mask
- Destination IP
- Source-Destination IP
- IP flow includes protocol and protocol ports
- Set mls flow destinationdestination-sourcefull
- Does not require an access list on route
processor - Log, reflexive, and established options not
allowed
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MLS-SE Configuration and Caching
- MLS Caching
- Candidate entries remain in cache for 5 seconds
- MLS entry deleted after aging time(default 256
seconds) - MLS entries can be purged by other events
- Applying access lists, routing changes, disabling
MLS - Configuration
- Set mls enable
- Set mls agingtime 200
- Set mls agingtime fast 32 pkt_threshold 3
- Set mls include n.n.n.n
- Clear mls include all
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Verifying MLS Configuration
- Show mls
- Status of mls
- Aging time for cache entries
- Fast aging time and packet threshold
- Flow mask
- Total packets switched
- Active MLS entries in cache
- Netflow enabled ports and hosts
- MLS-RP IP address, MAC accress, XTAG, VLANs
