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9 Cards in this Set
- Front
- Back
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For dot1q trunking, what is the definition of a native VLAN
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- Native VLAN is by default VLAN 1
- The native VLAN is for untagged traffic - This means it is the VLAN that layer 2 frames are forwarded to if it is received untagged on a 802.1Q trunk port. - 802.1Q trunks define a native VLAN for frames that are not tagged by feault. - 802.1Q trunk links employ the tagging mechanism to carry frames for multiple VLANs. - Each frame is tagged to identify the VLAN to which the frame belongs. e.g if a packet is destined for VLAN 10, the frame will be tagged to say that this packet is destined for VLAN 10 and nothing else. |
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Describe how IP unicast packets are rewritten during CEF
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The process is as follows:
- The source MAC address changes from the sender MAC address to the outgoing router MAC address. - The destination MAC address changes from the router MAC address to the next-hop MAC address (router-next hop) - The TTL (time to live) is decremented by one and, as a result, the IP header checksum is recalculated. - The frame checksum must be recalculated. - The switch obtains the info needed for the frame rewriting process from internal tables such as the CAM and TCAM. |
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CAM and TCAM tables
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CAM table -
The primary table used to make L2 forwarding decisions. - The table is built by recording the MAC address and inbound port of all incoming frames. - when a frame arrives at the switch with a destination MAC address of an entry in the CAM table, the frame is forwarded out through only the port that is associated with that specific MAC address. TCAM table - - Stores ACL, Qos and other info generally associated with L3 and up layer processing. - in specific high end switching platforms, the TCAM is a portion of memory designed for rapid hardware and L3 forwarding info for frames including CAM and ACL info. |
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Briefly describe the 802.11A, B, G, N and AC standards.
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Standard | Frequency band | BW | max data rate
802.11a | 5GHz | 20 MHz | 54 Mb/s 802.11b | 2.4 GHz | 20 MHz | 11 Mb/s 802.11g | 2.4 GHz | 20 MHz | 54 Mb/s 802.11n | 2.4 GHz | 20 MHz | 600 Mb/s | 5 GHz | 40 MHz 802.11ac | 5 GHz | 20,40,80 | 6.93 Gb/s | 80 + 80, | | 160 MHz | 802.11a - Extension to 802.11 developed by IEEE for wireless LAN technology (WLAN). 802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The 802.11a spec uses an orthogonal frequency division multiplexting encoding scheme rather than FHSS or DSSS and provides up to 54mbps in the 5GHz band. 802.11b - provides 11mbps tramission (w/ fallback to 5.5, 2 and 1 mbps) in the 2.4GHz band. 802.11b uses only DSSS (1999) 802.11g - used for transmission over short distances at up to 54mbps in the 2.4GHz band. 802.11n - builds upon previous 802.11 standards by adding multiple-input multiple-output (MIMO). allows for increased data and increased range. 802.11n operates on both the 2.4GHz and 5GHz bands and operates at a max data rate from 54mbps to 600mbps. 802.11ac - under development, based on 802.11n. changes compared to 802.11n are; wider channels (80 or 160Mhz vs 40 MHz) in the 5GHz band. addition of multi-user MIMO (MU-MIMO) |
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802.11.D, E, F, I, R, S
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802.11d - Global harmonization of spectrum to improve roaming from country to country.
802.11e - QoS - to improve transmission of video and audio 802.11f - Inter-LAN roaming from one AP to another 802.11i - Encryption, security, authentication with 802.1x 802.11r - Fast, wide-ranging roaming 802.11s - Mesh networking |
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exact purpose and context it is used -
instance <inst> vlan <range> |
- The purpose of this sequence is to map a range of VLANS to a MST instance
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exact purpose and context it is used -
port-channel load-balance src-dst-port |
- This sequence sets EtherChannel load balancing.
- It is based on source and destination TCP/UDP ports |
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Exact purpose and context it is used -
standby 99 ip 10.11.12.13 |
- This sequence associates an interface with HSRP standby group.
- it sets the virtual standby IP address (or default gateway) |
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Exact purpose and context it is used -
auto qos voip trust |
- This sequence specifies that the interface is connected to a trusted switch or router and that the VoIP classification of the incoming packet is to be trusted.
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