Cisco IOS Subnet Calculator

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Oct 24 2011

Cisco IOS Subnet Calculator

Quick one this morning. IOS has loads of pretty much undocumented features (e.g. using the “do” command in config mode) that make life so much easier. We’ve come across another one – the “terminal ip netmask-format” command. This allows you to display the netmask on an interface is one of three formats – bit-count (slash notation), decimal and hex. Avoids the constant use of all of those subnet calculators!

Router#terminal ip netmask-format bit
Router#show int f0/0.1
FastEthernet0/0.1 is up, line protocol is up
Hardware is Gt96k FE, address is 001b.d58f.76de (bia 001b.d58f.76de)
Internet address is 10.1.200.254/24
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1.
Keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of “show interface” counters never
Router#terminal ip netmask-format decimal
Router#show int f0/0.1
FastEthernet0/0.1 is up, line protocol is up
Hardware is Gt96k FE, address is 001b.d58f.76de (bia 001b.d58f.76de)
Internet address is 10.1.200.254 255.255.255.0
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1.
Keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of “show interface” counters never
Router#terminal ip netmask-format hex
Router#show int f0/1.1
FastEthernet0/0.1 is up, line protocol is up
Hardware is Gt96k FE, address is 001b.d58f.76de (bia 001b.d58f.76de)
Internet address is 10.1.200.254 0xFFFFFF00
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1.
Keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of “show interface” counters never

Barry Hesk

Cisco announces new Nexus Switches and ASA

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20th October 2011

Cisco announces new Nexus Switches

Cisco today announced their latest iteration of the Nexus coverged storage and data switches.

Network World have a good article covering the announcements

In summary:

  • New switching fabric called imaginatively, “fabric-2” which scales to 550GB per slot – more than twice the thoughput on the original fabric.
  • New Nexus 3016 which provides 16 ports of 40GB Ethernet.
  • New Nexus 4048 – provides 48 10/100/1000 Mbps ports plus 10GB uplinks
  • Fabricpath support for the Nexus 5500 series providing multiple active layer 2 paths across a “top of rack” topology
  • ASA 1000V firewall – Cisco’s first purely software based firewall – using the same underlying technology as the 1000V switch

Price points are said to be “competitive” – which for Nexus probably means “expensive”.

Barry Hesk