Network Engineering Stack Exchange Community Digest

Top new questions this week:

How does the shortage of IPv4 public IPs influence existing firewalls?

I came to know recently IPv4 public IP address pools are going to be exhausted soon. If IPv6 addresses are fully in use, all device vendors like Cisco, Fortinet, Palo Alto have to redesign their ...

ipv4 network ipv6  
asked by Sunilsp 6 votes
answered by Ron Trunk 20 votes

Working in packet tracer, can I configure two routing protocols

I am working on network lab designing topology. I am able to configured two routing protocols which surprised me. I configured RIP and OSPF routing protocols in layer3 switch and advertised same ...

routing router packet-tracer  
asked by K Raghu 3 votes
answered by Ron Maupin 2 votes

IGMP Snooping issue. probably

I have multicast hosts that keep leaving a group, only to join back up which results in loss of video feeds. The network consists of a variety of Cisco 2960's and a Cisco 9300 w/ PIM Sparse mode set ...

multicast igmp  
asked by Rnet 2 votes

What exactly is "network automation"?

When we say network automation, what "automation" are we talking about? What is that being automated? I've heard that in network automation we do not have to configure each individual ...

network networking sdn ubiquiti automation  
asked by Noob_Guy 1 vote
answered by Ron Trunk 1 vote

Access list command for specific IP range in Cisco Router 1921

For example: router(config)#ip access-list extended 101 router(config-ext-nacl)#10 per icmp any host 192.168.1.10 From second command line, how to write a command permit icmp any host range ...

cisco router acl command  
asked by Tony Lee 1 vote
answered by JFL 4 votes

Redundant routers (HSRP, GLBP, ... ) with single T1 circuit

I have two sites connected by a T1 circuit. Currenlty I have only a single router on both ends, but I would like to add redundantcy, HSRP, GLBP, or simular in case a router fails (see picture). Is ...

hsrp redundant-routes serialization glbp  
asked by Frank 1 vote
answered by Zac67 2 votes

VLAN Filtering not working

On Cisco devices I'm looking to enable some filtering for one specific vlan (id 110). Here is my config : (192.33.57.177 is the DHCP server host) ip access-list extended VLAN110-DHCP permit ip any ...

cisco vlan acl  
asked by Jeremy G. 1 vote
answered by Darrell Root 5 votes

Greatest hits from previous weeks:

Stateful vs Stateless IPv6?

What's the difference here? Are stateful IPv6 entries retained in the DHCPv6 server?

cisco dhcp ipv6 dhcpv6  
asked by stets 8 votes
answered by YLearn 12 votes

What is the actual size of an Ethernet MTU

I think I might be getting confused with terminology surrounding MTU. This definition from Wendell Odom's CCNA book on MTU: The IEEE 802.3 specification limits the data portion of the 802.3 frame ...

ethernet protocol-theory mtu  
asked by Josh 33 votes
answered by Gerben 38 votes

Why is fe80::/10 reserved for link local addresses when fe80::/64 is actually used?

I understand that IPv6 reserves the fe80::/10 prefix for link local addresses, and that hosts select an address with a /64 prefix. Why is the reserved space so much larger than what is actually used ...

ipv6  
asked by Craig Constantine 43 votes
answered by Jeremy Stretch 31 votes

How can I diagnose a bridging (ethernet) loop?

Given that spanning tree has failed (or you don't have any spanning tree) and get an ethernet loop, what's the best way to diagnose where the problem is? Which switch?, which cable? and so on.

ethernet switch  
asked by nos 43 votes
answered by Daniel Dib 31 votes

Why does DHCP use UDP and not TCP?

DHCP uses UDP as its transport protocol. DHCP messages that a client sends to a server are sent to well-known port 67 (UDP—Bootstrap Protocol and DHCP). DHCP Messages  that a server sends to a client ...

tcp dhcp networking udp  
asked by Aymen Guidad 26 votes
answered by Mario Jost 74 votes

Reset admin password on Fortinet FortiWiFi 60D

I've tried to log in to this device by doing the following. Default credentials username: admin password: <none> Maintainer credentials in the FortiExplorer console interface. username: ...

router wireless fortinet  
asked by Nick C. 6 votes
answered by Ricky Beam 3 votes

How do you calculate the prefix, network, subnet, and host numbers?

Example: IP: 128.42.5.4 In binary: 10000000 00101010 00000101 00000100 Subnet: 255.255.248.0 How could you determine the prefix, network, subnet, and host numbers?

ip ipv4 subnet ip-address  
asked by user5032 114 votes
answered by Mike Pennington 179 votes
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