From: Iamgoingtobeaccie
Date: Thu Dec 21 2006 - 02:06:16 ART
Hi,
Thanks a lot.If the router decrements the TTL when it forwards,in the case of EBGP even the directly connected neighbor will not receive the packet as the TTL is 1.So EBGP's TTL is not 1???
Ronnie Angello <ronnie.angello@gmail.com> wrote: RFC 1812, page 84:
A router MUST generate a Time Exceeded message Code 0 (In Transit) when it discards a packet due to an expired TTL field. A router MAY have a per-interface option to disable origination of these messages on that interface, but that option MUST default to allowing the messages to be originated.
RFC 1812, page 85:
The Time-to-Live (TTL) field of the IP header is defined to be a timer limiting the lifetime of a datagram. When a router *forwards* a packet, it MUST reduce the TTL by at least one. If it holds a packet for more than one second, it MAY decrement the TTL by one for each second.
On 12/20/06, Nawaz, Ajaz < Ajaz.Nawaz@bskyb.com> wrote:Tim
So what occurs when it receives an update with TTL of two or three for
example?
Are you suggesting it decrements that once for it's own use?
What happens when it forwards this update to an onwards hop?
Ajaz
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Tim
Sent: 20 December 2006 16:08
To: Nawaz, Ajaz; 'Iamgoingtobeaccie Iamgoingtobeaccie';
ccielab@groupstudy.com
Subject: RE: TTL
Ajar,
I'm pretty sure the TTL is decremented on Ingress. When a router receives a
packet with a TTL of 1, the TTL is decremented making the TTL 0 and causing
the router to send icmp time-exceeded message back.
Please correct me if I'm mistaken.
Thanks, Tim
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Nawaz, Ajaz
Sent: Wednesday, December 20, 2006 5:48 AM
To: Iamgoingtobeaccie Iamgoingtobeaccie; ccielab@groupstudy.com
Subject: RE: TTL
Egress. You can prove it easily through testing.
Hth
Ajaz Nawaz
CCIE#15721
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
sabrina pittarel
Sent: 20 December 2006 06:52
To: Iamgoingtobeaccie Iamgoingtobeaccie; ccielab@groupstudy.com
Subject: Re: TTL
Hi,
let's put it in this way...a router will never forward a packet that has
been received with TTL equal to 0 or 1
Sabrina
----- Original Message ----
From: Iamgoingtobeaccie Iamgoingtobeaccie <heyiamgoingtobeaccie@yahoo.co.in>
To: ccielab@groupstudy.com
Sent: Tuesday, December 19, 2006 5:29:43 AM
Subject: TTL
GS,
Can someone let me know where does the TTL get
decremented? Is it on the ingress of the receiving router or on the egress
of
the sending router.
When I configure EBGP between two routers with
their loopback IP addresses and enable 'debug ip packet',I am not seeing any
packet coming in.So I assume that the TTL is decremented on the egress
interface of the sending router.Can someone confirm.
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