Configuration Guide User guide

FastIron Configuration Guide 1039
53-1002494-02
Configuring IP parameters – Layer 2 Switches
After you enter the command, a message indicating that the DNS query is in process and the
current gateway address (IP address of the domain name server) being queried appear on the
screen.
NOTE
In the previous example, 209.157.22.199 is the IP address of the domain name server (default DNS
gateway address), and 209.157.22.80 represents the IP address of the NYC02 host.
FIGURE 119 Querying a Host on the newyork.com Domain
Changing the TTL threshold
The time to live (TTL) threshold prevents routing loops by specifying the maximum number of router
hops an IP packet originated by the Layer 2 Switch can travel through. Each device capable of
forwarding IP that receives the packet decrements (decreases) the packet TTL by one. If a router
receives a packet with a TTL of 1 and reduces the TTL to zero, the router drops the packet.
The default TTL is 64. You can change the TTL to a value from 1 through 255.
To modify the TTL threshold to 25, enter the following commands.
Brocade(config)# ip ttl 25
Brocade(config)# exit
Syntax: ip ttl <1-255>
Type Control-c to abort
Sending DNS Query to 209.157.22.199
Tracing Route to IP node 209.157.22.80
To ABORT Trace Route, Please use stop-traceroute command.
Traced route to target IP node 209.157.22.80:
IP Address Round Trip Time1 Round Trip Time2
207.95.6.30 93 msec 121 msec
...
...
[
Layer 3 Switch
Domain Name Server
nyc02
nyc01
nyc01
nyc02
207.95.6.199
newyork.com