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Nexus 1000v www.silantia.com 1 IGMP Snooping DHCP Snooping Dynamic ARP Inspection (DAI) IP Source Guard Port Security Access Control Lists (ACL) Private VLANs (PVLAN)

Nexus 1000v part ii

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Page 1: Nexus 1000v part ii

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Nexus 1000v

IGMP Snooping DHCP Snooping Dynamic ARP Inspection

(DAI) IP Source Guard Port Security Access Control Lists (ACL) Private VLANs (PVLAN)

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Nexus 1000v IGMP snooping

Nexus 1000v VEM can snoop IGMP conversation between VM adapter and router (default gateway).

Nexus 1000v is full IGMP snooping bridge but it cannot perform IGMP querier job.

ip igmp snooping ! Enables at global level

vlan 200

ip igmp snooping ! Enables per vlan IGMP snooping

ip igmp snooping explicit-tracking

ip igmp snooping mrouter interface ethernet 2/1

! vEths are not supported as router ports

ip igmp snooping static-group 230.0.0.1 interface vethernet 21

show ip igmp snooping vlan 200

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Nexus 1000v Layer 2 Security feature

Works exactly similar to Layer 2 security features in physical switches.

Security features requires Nexus 1000v Advanced License.

Layer 2 security is important in Virtual Desktop Infrastructure type of environment where each virtual machine is a user desktop.

Unmanaged VMs can bring down the whole Layer 2 network if it is not protected at VEM level.

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Nexus 1000v Port-security

MAC-to-Port Mapping Don't allow any MAC addresses other than those mapped

to pass traffic Static = Static MAC-to-Port Mapping Dynamic = Learn the MAC, map to the port, then don't

allow anyone ELSE Can also age this dynamic mapping out

Sticky = Same as dynamic, but store mapping VSM Violations

Shutdown = Shuts port down. Simple, done. Restrict = Drops traffic from any Other MAC addresses Protect = Basically drops traffic from any other MACs like

Restrict, but first it learns the MAC of the 1st violator and logs him (still drops his traffic too)and doesn't learn any other violators' MACs

Page 5: Nexus 1000v part ii

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Nexus 1000v Port-security

You can configure port security only on Layer 2 interfaces Details about port security and different types of

interfaces or ports are as follows: Access ports

You can configure port security on interfaces that you have configured as Layer 2 access ports

On an access port, port security applies only to the access VLAN Trunk ports

You can configure port security on interfaces that you have configured as Layer 2 trunk ports

The device allows VLAN maximums only for VLANs associated with the trunk port

SPAN ports You can configure port security on SPAN source ports but not on

SPAN destination ports

Page 6: Nexus 1000v part ii

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Nexus 1000v DHCP snooping

DHCP snooping functions like a firewall between untrusted hosts and trusted DHCP servers by doing the following: Validates DHCP messages received from untrusted sources and

filters out invalid response messages from DHCP servers. Builds and maintains the DHCP snooping binding database, which

contains information about untrusted hosts with leased IP addresses.

Uses the DHCP snooping binding database to validate subsequent requests from untrusted hosts.

Dynamic ARP Inspection (DAI) and IP Source Guard also use information stored in the DHCP snooping binding database.

When you enable DHCP snooping, by default, all vEthernet (vEth) ports are untrusted and all Ethernet ports (uplinks), port channels, special vEth ports are trusted.

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Nexus 1000v DHCP snooping

DHCP operations are categorized into four basic phases: IP Discovery IP Lease Offer IP Request IP Lease Acknowledgement

Only DHCP messages that come from a server that is connected to a trusted port are accepted.

Any DHCP message on UDP port 68 that is data from the server to the client that is received on an untrusted port is dropped. Nexus 1000v VEM builds and maintains the DHCP snooping binding database, which contains information about clients with leased IP addresses.

Uses the DHCP snooping binding database to validate subsequent requests from clients.

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Nexus 1000v DHCP snooping

Configuration Enable the DHCP feature.

feature dhcp Enable DHCP snooping globally.

ip dhcp snooping   Enable DHCP snooping on at least one VLAN.By default,

DHCP snooping is disabled on all VLANs. Ensure that the ip dhcp snooping vlan vlan-list  DHCP server is connected to the device using a trusted

interface.N1KV-VSM(config)# port-profile profilename 

N1KV-VSM(config-port-profile)# ip dhcp snooping trust  Configuring the Rate Limit for DHCP PacketsN1KV-VSM(config-if)#[no] ip dhcp snooping limit rate rate

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Nexus 1000v DHCP snooping

Configuration Error disable detection and recovery errdisable detect cause dhcp-rate-limit 

Enables DHCP error-disabled detection.errdisable recovery cause dhcp-rate-limit Enables DHCP error-disabled detection.errdisable recovery interval time interval  Sets the DHCP error-disabled recovery interval, where time

interval is the number of seconds from 30 to 65535.

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Nexus 1000v DHCP snooping

VerificationN1KV-VSM# show ip dhcp snooping

Switch DHCP snooping is enabled

DHCP snooping is configured on the following VLANs:

100,200,250-252

DHCP snooping is operational on the following VLANs:

100,200,250-252

Insertion of Option 82 is disabled

Verification of MAC address is enabled

DHCP snooping trust is configured on the following interfaces:

Interface Trusted Pkt Limit

------------ ------- ---------

Vethernet1 No Unlimited

Vethernet2 No Unlimited

Vethernet3 Yes 15

Vethernet4 No Unlimited

Vethernet5 No Unlimited

Page 11: Nexus 1000v part ii

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Nexus 1000v DHCP snooping

VerificationN1KV-VSM# show ip dhcp snooping statistics

Packets processed 0

Packets forwarded 0

Total packets dropped 0

Packets dropped from untrusted ports 0

Packets dropped due to MAC address check failure 0

Packets dropped due to Option 82 insertion failure 0

Packets dropped due to o/p intf unknown 0

Packets dropped which were unknown 0

Packets dropped due to service dhcp not enabled 0

Packets dropped due to no binding entry 0

Packets dropped due to interface error/no interface 0

Packets dropped due to max hops exceeded 0

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Nexus 1000v Dynamic ARP inspection

DAI ensures that only valid ARP requests and responses are relayed by intercepting all ARP requests and responses on untrusted ports and verifying that each of these intercepted packets has a valid IP-to-MAC address binding before updating the local ARP cache or before forwarding the packet to the appropriate destination.

DAI depends on the entries in the DHCP snooping binding database to verify IP-to-MAC address bindings in incoming ARP requests and ARP responses.

DAI is supported on vEthernet interfaces and private VLAN ports

Page 13: Nexus 1000v part ii

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Nexus 1000v Dynamic ARP inspection

Configuration:N1KV-VSM(config)# ip arp inspection vlan #

N1KV-VSM(config)# port-profile profilename

N1KV-VSM(config-port-profile)# ip arp inspection trust 

Verificationswitch# show ip arp inspection interfaces vethernet 3 Interface Trust State Pkt Limit Burst Interval

------------- ----------- --------- ----------------

Vethernet9 Untrusted 30 5

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Nexus 1000v Dynamic ARP inspection

Rate limiting ip arp inspection limit {rate pps [burst interval l bint] | none} 

Configures the specified ARP inspection limit on the interface or the port profile as follows. rate—Specifies that allowable values are between 1

and 2048 packets per second (pps). The untrusted interface default is15 packets per second. The trusted interface default is15 packets per second.

burst interval—Specifies that allowable values are between 1 and 15 seconds (the default is 5 seconds).

none—Specifies an unlimited number of packets per second.

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Nexus 1000v Dynamic ARP inspection

Can enable additional validation checks ip arp inspection validate ? src-mac: Checks the source MAC address in the Ethernet header against the

sender MAC address in the ARP body for ARP requests and responses

dst-mac: Checks the destination MAC address in the Ethernet header against the target MAC address in the ARP body for ARP responses

ip: Checks the ARP body for invalid and unexpected IP addresses. Addresses include 0.0.0.0, 255.255.255.255, and all IP multicast addresses

arp access-list UNK-SW permit ip host 10.0.0.1 mac host 0000.0000.0001 ip arp inspection filter UNK-SW vlan 10

Error disable Port may go into error disable when ARP inspection is violated.

N1KV-VSM(config)# errdisable detect cause arp-inspection

N1KV-VSM(config)# errdisable recovery cause arp-inspection You can shut no shut port or configure error disable recovery to recover automatically.

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Nexus 1000v IP Source Guard

IP SG is a per-interface traffic filter that permits IP traffic only when the IP address and MAC address of each packet matches one of two sources of IP and MAC address bindings Entries in DHCP snooping binding table. Static IP source entries that you configure.

You can enable IP Source Guard on Layer 2 interfaces that are not trusted by DHCP snooping.

When you initially enable IP Source Guard, all inbound IP traffic on the interface is blocked except for the following: DHCP packets, which DHCP snooping inspects and then

forwards or drops, depending upon the results of inspecting the packet.

IP traffic from a source whose static IP entries are configured in the Cisco Nexus 1000V.

Page 17: Nexus 1000v part ii

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Nexus 1000v IP Source Guard

Configuration: (can be done under port-profile)N1KV-VSM(config)# interface vethernet 31

N1KV-VSM(config-if)# ip verify source dhcp-snooping-vlan

Verification: switch (config-if)# show ip verify source interface vethernet 3

Filter Mode(for static bindings): IP-MAC IP source guard is enabled on this interface.

Interface Filter-mode IP-address Mac-address Vlan

---------- ----------- ---------- ----------- ----

Vethernet3 active 1.182.56.137 00:50:56:82:56:3e 1053

Adding Static entry in for IP SG.N1KV-VSM(config)# ip source binding 10.5.22.17 001f.28bd.0013 vlan 100 interface vethernet 3

Page 18: Nexus 1000v part ii

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Nexus 1000v DAI and IPSG

Page 19: Nexus 1000v part ii

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Nexus 1000v ACL

Two types of ACLs are supported in Nexus 1000v IP ACL- Applied only to IP traffic MAC ACL – Applied only to Non IP traffic

Order of ACL application Ingress port ACL Egress port ACL

MAC ACL supports following additional filtering options.

Layer 3 protocolVLAN ID Class of Service (CoS)

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Nexus 1000v IP ACL

IP ACL supports following additional filtering options. Layer 4 protocol TCP and UDP ports ICMP types and codes IGMP types Precedence level Differentiated Services Code Point (DSCP) value TCP packets with the ACK, FIN, PSH, RST, SYN, or URG bit

set All ACL are configured via CLI on VSM and when ACLs

are applied to port-profile or veth/ethernet port it will be processed at VEM level.

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Nexus 1000v IP ACL

Configuration example:ip access-list DENY_OSPF

10 deny ip any 224.0.0.5/32

20 deny ip any 224.0.0.6/32

30 permit ip any any

ip access-list DENY_TELNET

10 deny tcp any 150.10.2.1/32 eq telnet

20 permit ip any any

port-profile type veth SERVERFARM1

ip access-group DENY_TELNET in

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Nexus 1000v Private VLANs

Private VLANs partition a regular VLAN domain into subdomains and can have multiple VLAN pairs.

All VLAN pairs in a private VLAN share the same Primary VLAN. The secondary VLAN ID differentiates one subdomain from another.

All members in the private VLAN share a common address space, which is allocated to the primary VLAN.

Private VLANs can span multiple switches. A trunk port carries the primary VLAN and secondary VLANs to a neighboring switch. (uplink ports in case of Nexus 1000v)

Page 23: Nexus 1000v part ii

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Nexus 1000v Private Vlans

Enable private vlan and configure primary and secondary vlans

feature private-vlanvlan 153private-vlan primaryprivate-vlan association 154-155vlan 154private-vlan communityvlan 155private-vlan isolated

Page 24: Nexus 1000v part ii

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Nexus 1000v Private Vlans

! Private vlan configured on port-profileport-profile type vethernet pv154vmware port-groupswitchport mode private-vlan hostswitchport private-vlan host-association 153 154no shutdownstate enabled

! You can configure private vlan on Veth port itself.port-profile type vethernet pv155vmware port-groupswitchport mode private-vlan hostswitchport private-vlan host-association 153 155no shutdownstate enabled!

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Nexus 1000v Private Vlans

Create uplink port-profile carrying private vlans.

port-profile type ethernet pcpvtrunkvmware port-groupswitchport mode private-vlan trunk promiscuousswitchport private-vlan mapping trunk 153 154-155switchport private-vlan trunk allowed vlan 153-155channel-group auto mode on mac-pinningno shutdownstate enabled