Term
| What pins does a PC NIC card transmit on? |
|
Definition
|
|
Term
| What pins does a PC NIC card receive on? |
|
Definition
|
|
Term
| What pins does a switch transmit on? |
|
Definition
| Pins 3 and 6. "3, 6 -- switch transmits" |
|
|
Term
| What pins does a switch receive on? |
|
Definition
|
|
Term
| How can the switch detect link speed? |
|
Definition
1) Via Fast Link Pulses (FLP) in the auto-negotiation process
2) Based on incoming electrical signal |
|
|
Term
| What is the default duplex for a 1 G port? |
|
Definition
|
|
Term
| What is the default duplex for a 10 or 100 Mbps port? |
|
Definition
|
|
Term
| How many bytes in an 802.3 MAC header? |
|
Definition
22
8 -- preamble and start of frame
6 -- dest MAC
6 -- source MAC
2 -- Type/Length |
|
|
Term
| What is the FCS in 802.3? |
|
Definition
| 4 byte frame check sequence at the end of the frame. |
|
|
Term
| What 3 functions does 802.3 perform? |
|
Definition
| Medium access, error detection and framing. |
|
|
Term
| What IEEE standard defines Ethernet Link Layer Control (LLC)? |
|
Definition
|
|
Term
| What function does 802.2 LLC provide? |
|
Definition
| Allows multiple upper layer protocols to share use of data link. |
|
|
Term
| What are the fields in 802.2 header? |
|
Definition
1 byte -- DSAP (destination service access point)
1 byte -- SSAP (source SAP)
1 - 2 bytes -- Control (allows for connection or connectionless operation, generally only for connectionless with a 1 byte value of 0x03) |
|
|
Term
| What does a DSAP value of 0xaa indicate? |
|
Definition
| 0xaa is an indication to use SNAP and look at 5 additional bytes in header for upper layer protocol. |
|
|
Term
| What are the fields in the SNAP header? |
|
Definition
3 bytes -- OUI (but rarely used)
2 bytes -- type (upper layer protocol) |
|
|
Term
| What is the IEEE standard for Fast Ethernet over copper and optical? |
|
Definition
|
|
Term
| What is the IEEE standard for GigE over optical? |
|
Definition
802.3Z
"you can Z far with optical"
(100 km with 1000Base-ZX) |
|
|
Term
| What is the IEEE standard for GigE over copper? |
|
Definition
|
|
Term
| Of what significance is the leftmost bit in canonical bit order? |
|
Definition
| Leftmost is least significant. |
|
|
Term
| What are the two most significant bits in the 1st byte of a MAC address? |
|
Definition
U/L | I/G
Most significant: I/G
Second most significant: U/L |
|
|
Term
| What is the I/G bit for in a MAC address? |
|
Definition
0 if this is a unicast address
1 if this is a multicast/broadcast address |
|
|
Term
| What does it mean if the U/L bit is set to 0 in a MAC address? |
|
Definition
| U/L bit = 0 means this is a vendor assigned MAC address. |
|
|
Term
| What does it mean if the U/L bit is set to 1 in a MAC address? |
|
Definition
| U/L = 1 means this is an administratively assigned MAC address |
|
|
Term
| What is the only defined MAC Control frame in the MAC Control Sublayer? |
|
Definition
| The MAC Control PAUSE frame is sent to multicast address 0180.C200.0001 to tell the receiver to wait before sending more frames. |
|
|
Term
| When is the use of Ethernet flow control negotiated? |
|
Definition
| The use of PAUSE frames for flow control happens during auto negotiation. |
|
|
Term
| What is used for auto-negotiation on GigE links? |
|
Definition
|
|
Term
| When is auto-negotiation appropriate? |
|
Definition
| Use auto-negotiation when connecting to end users or transient users. |
|
|
Term
| When is it best to hard-code speed and duplex? |
|
Definition
| Switch to switch, switch to server, switch to router. |
|
|
Term
| Can you auto-negotiate speed and hard-code duplex? |
|
Definition
| No, speed must be manually configured before duplex is manually configured. |
|
|
Term
| What color is a err-disabled port LED? |
|
Definition
|
|
Term
| What are 5 causes of errDisable? |
|
Definition
1) Excessive collisions (> 16 in a row)
2) bpduguard
3) UDLD
4) Etherchannel misconfig
5) L2 protocol tunnel config |
|
|
Term
| Name 3 causes of flooding in switched networks and possible solutions. |
|
Definition
1) Asymmetric routing (fix: configure switch MAC aging time = router ARP aging time 14400 seconds)
2) Frequent TCNs (minimize with use of portfast)
3) forwarding table overflow (use 802.1X or psec) |
|
|
Term
| How many destination span ports can be configured per switch? |
|
Definition
|
|
Term
| If you are monitoring a tx session on a port, which of the following are applied before going to SPAN port: ACL, VACL, QoS, policing? |
|
Definition
| All of them. For tx SPAN sessions, ACL, VACLs, QoS and policing are applied before traffic is spanned. |
|
|
Term
| How do you send SPAN traffic from one device to another without routing? |
|
Definition
| Use RSPAN to configure a special "remote span" VLAN on all switches between source and destination. |
|
|
Term
| What technology enables routing of spanned traffic? |
|
Definition
| ERSPAN uses GRE tunnels to route spanned traffic. |
|
|
Term
What is VLAN 199 given this config:
vlan 199
remote span |
|
Definition
| Vlan 199 is an RSPAN vlan. |
|
|
Term
| What ACL numbers can be used for MAC address ACLs? |
|
Definition
|
|
Term
| What ACL numbers can be used for ethernet type ACLS? |
|
Definition
|
|
Term
| What is the MTU of a PPPoE frame? |
|
Definition
| 1492 bytes (accounts for 8 byte header that PPP adds) |
|
|
Term
| What happens to a PPPoE connection if MTU doesn't match between client and server? |
|
Definition
| The PPPoE negotiation will fail. |
|
|
Term
| What protocol enables the concept connection or circuit on Ethernet and adds features to protect against IP and MAC conflicts and rogue DHCP servers? |
|
Definition
| PPPoE users can virtually "dial" from one machine to another over an Ethernet network, establish a point to point connection between them and then securely transport data packets over the connection |
|
|
Term
| How do you disable auto-negotiation on an Ethernet port? |
|
Definition
| Manually configure speed AND duplex. |
|
|
Term
| What's the quickest way to enable vtp pruning in a domain? |
|
Definition
| Configure it on the server. |
|
|
Term
| What are two motivations for PVLANs? |
|
Definition
1) Better LAN security
2) IP subnet conservation (separate VLANs on same subnet) |
|
|
Term
| What kind of PVLAN can talk to primary VLAN and others in their secondary VLAN (but not any other secondary VLAN) ? |
|
Definition
| Community (e.g. Employee ports) |
|
|
Term
| What kind of PVLAN can talk to primary VLAN but no others in any secondary VLAN (including their own)? |
|
Definition
| Isolated (e.g. Guest ports) |
|
|
Term
| In RSTP, which timers (Hello, fwd delay, etc) does a switch use -- its own or the roots? |
|
Definition
| Always the root. One of the roles of the root bridge is to set timers and properties of the tree |
|
|
