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Layer 3 Forward and ARP Configuration 
Chapter 1 Layer 3 Management Configuration 

http://www.level1.com

                                                                                                                    1-6 

Command 

Explanation 

Admin Mode 

 

clear ipv6 neighbors   

Clear all static neighbor table entries. 

 

1.2.3 IPv6 Troubleshooting 

  If  the  connected  PC  has  not  obtained  IPv6  address,  you  should  check  the  RA 

announcement switch (the default is turned off) 

1.3 Static Route 

1.3.1 Introduction to Static Route 

As mentioned earlier, the static route is the manually specified path to a network or a 

host. Static route is simple and consistent, and can prevent illegal route modification, and 

is  convenient  for  load  balance  and  route  backup.  However,  it  also  has  its  own  defects. 

Static  route,  as  its  name  indicates,  is  static,  it  won’t  modify  the  route  automatically  on 

network failure, and manual configuration is required on such occasions, therefore it is not 

suitable for mid and large-scale networks.   

Static  route  is  mainly  used  in  the  following  two  conditions:  1)  in  stable  networks  to 

reduce load of route selection and routing data streams. For example, static route can be 

used in route to STUB network. 2) For route backup, configure static route in the backup 

line, with a lower priority than the main line.   

Static route and dynamic route can coexist; layer3 switch will choose the  route with 

the highest priority according to the priority of routing protocols. At the same time, static 

route  can  be  introduced  (redistribute)  in  dynamic  route,  and  change  the  priority  of  the 

static route introduced as required.   

1.3.2 Introduction to Default Route 

Default route is a kind of static route, which is used only when no matching route is 

found. In the route table, default route in is indicated by a destination address of 0.0.0.0 

and a network mask of 0.0.0.0, too. If the route table does not have the destination of a 

packet  and has  no  default  route  configured,  the packet  will  be discarded,  and  an  ICMP 

packet will be sent to the source address indicate the destination address or network is 

unreachable. 

Summary of Contents for GTL-2890

Page 1: ...Layer 3 Forward and ARP Configuration Content http www level1 com 1 GTL 2890 GTL 5260 Layer 3 Forward and ARP Configuration...

Page 2: ...2 Introduction to Default Route 1 6 1 3 3 Static Route Configuration Task List 1 7 1 3 4 Static Route Configuration Examples 1 7 1 4 ARP 1 8 1 4 1 Introduction to ARP 1 8 1 4 2 ARP Configuration Task...

Page 3: ...P GUARD CONFIGURATION TASK LIST 4 2 CHAPTER 5 GRATUITOUS ARP CONFIGURATION 5 1 5 1 INTRODUCTION TO GRATUITOUS ARP 5 1 5 2 GRATUITOUS ARP CONFIGURATION TASK LIST 5 1 5 3 GRATUITOUS ARP CONFIGURATION EX...

Page 4: ...or contain no layer 2 ports At least one of the Layer 2 ports contained in Layer 3 interface should be in UP state for Layer 3 interface in UP state otherwise Layer 3 interface will be in DOWN state T...

Page 5: ...With the greatly and continuously boosting of Internet services and application devices Home and Small Office Network IP phone and Wireless Service Information Terminal which make use of Internet whi...

Page 6: ...Automatic address configuration function also makes the readdressing of existing network easier and more convenient and it is more convenient for network operators to manage the transformation from o...

Page 7: ...only saves network bandwidth but enhances network efficiency as well 1 2 2 IP Configuration Layer 3 interface can be configured as IPv4 interface IPv6 interface 1 2 2 1 IPv4 Address Configuration IPv4...

Page 8: ...ace Configuration Mode ipv6 nd dad attempts value no ipv6 nd dad attempts Set the neighbor query message number sent in sequence when the interface makes duplicate address detection The no command res...

Page 9: ...ic route is mainly used in the following two conditions 1 in stable networks to reduce load of route selection and routing data streams For example static route can be used in route to STUB network 2...

Page 10: ...ateway interface distance command deletes a static route entry 1 3 4 Static Route Configuration Examples The figure shown below is a simple network consisting of three layer3 switches the network mask...

Page 11: ...established between PC A and PC C and PC B and PC C 1 4 ARP 1 4 1 Introduction to ARP ARP Address Resolution Protocol is mainly used to resolve IP address to Ethernet MAC address Switch supports stat...

Page 12: ...3 Management Configuration http www level1 com 1 9 If ARP has not been learned then enabled ARP debugging information and view the sending receiving condition of ARP packets Defective cable is a comm...

Page 13: ...o prevent ARP scanning if there is any host or port with ARP scanning features is found in the segment the switch will cut off the attack source to ensure the security of the network There are two met...

Page 14: ...lly 2 Configure the threshold of the port based and IP based ARP Scanning Prevention Command Explanation Global configuration mode anti arpscan port based threshold threshold value no anti arpscan por...

Page 15: ...arpscan recovery time Set automatic recovery time 6 Display relative information of debug information and ARP scanning Command Explanation Global configuration mode anti arpscan log enable no anti arp...

Page 16: ...peration of the system SWITCH A configuration task sequence SwitchA config anti arpscan enable SwitchA config anti arpscan recovery time 3600 SwitchA config anti arpscan trust ip 192 168 1 100 255 255...

Page 17: ...ntion Function Configuration http www level1 com 2 5 2 4 ARP Scanning Prevention Troubleshooting Help ARP scanning prevention is disabled by default After enabling ARP scanning prevention users can en...

Page 18: ...it will also insert an entry to its ARP cache table so it creates a possibility of ARP spoofing If the hacker wants to snoop the communication between two host computers in the same network even if ar...

Page 19: ...etworks is to disable switch automatic update function the cheater can t modify corrected MAC address in order to avoid wrong packets transfer and can t obtain other information At one time it doesn t...

Page 20: ...to A firstly A sends ARP reply packet to switch format is 192 168 2 3 00 00 00 00 00 01 mapping its MAC address to C s IP so the switch changes IP address when it updates ARP list then data packet of...

Page 21: ...0 00 00 02 interface ethernet 1 0 2 Switch config if vlan1 arp 192 168 2 3 00 00 00 00 00 03 interface ethernet 1 0 3 Switch Config If Vlan3 exit Switch Config ip arp security learnprotect Switch Conf...

Page 22: ...PC2 is mapped to an illegal MAC address which will prevent PC2 from receiving the messages to it Particularly if the attacker pretends to be the gateway and do ARP cheating the whole network will be...

Page 23: ...ttp www uttglobal com 4 2 scheme Please refer to relative documents for details 4 2 ARP GUARD Configuration Task List 1 Configure the protected IP address Command Explanation Port configuration mode a...

Page 24: ...C address of the gateway If the switch advertises gratuitous ARP requests the host will not have to send these requests This will reduce the frequency the hosts sending ARP requests for the gateway s...

Page 25: ...re above interface VLAN10 whose IP address is 192 168 15 254 and network address mask is 255 255 255 0 in the switch system Five PCs PC1 PC2 PC3 PC4 PC5 are connected to the interface Gratuitous ARP c...

Page 26: ...ARP send If gratuitous ARP is enabled in global configuration mode it can be disabled only in global configuration mode If gratuitous ARP is configured in interface configuration mode the configuratio...

Page 27: ...a packet is received from the trusted port the switch will not inspect it and forward it directly If the ARP data packet is received from the untrusted port the switch will only forward the lawful dat...

Page 28: ...e DHCP server is 00 24 8c 01 05 90 the IP address of 192 168 10 2 needs to be distributed statically the DHCP server is connected to e 1 0 1 The MAC of the specific server Other Server is 00 24 8c 01...

Page 29: ...t rate 50 interface Vlan10 ip address 192 168 10 1 255 255 255 0 Explanation In this case there are two method of static and dynamic using of DAI The ARP packets from the untrusted port will all be tr...

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